EPA Environmental Science Series: Improving urban water quality
Seminar 29 Mar 2021 Transcript

Good afternoon my name is Dr Carolyn Brumley Victoria's acting chief environmental scientist at EPA and it's my pleasure to welcome you online today to the Environment Protection Authority Victoria's first environmental science seminar series event for 2021. This event focuses on stormwater management and we are very pleased to welcome a special panel of guest speakers with us from The University of Melbourne Associate Professor Chris Walsh, Professor Tim Fletcher and Dr Stephanie Lavau. I would like to begin by acknowledging the aboriginal people as the First People and traditional custodians of the land and water on which we live work and depend. We pay our respects to aboriginal elders past and present. As Victoria's environmental regulator we pay our respects to how country has been protected and cared for by aboriginal people over many tens of thousands of years. We recognise the unique spiritual and cultural significance of land water and all that is in the environment and the continuing connection and aspirations for country of aboriginal people and traditional custodians. A few notes on this live stream event. The structure of today's events will feature an introduction by myself, short presentations by all three panellists, time for Q and A and wrapping up with a conclusion. This event will be recorded so if you need to leave early or miss parts of this session you can watch it again later via the EPA website. This session has live closed captions to ensure it's accessible for all. We will provide time at the end of the Q and A session and we welcome people to please ask questions using the box at the bottom of the screen. The Q and A will be open throughout the event but we will respond to questions after the presentations. We will try to get to as many as we can and all questions not answered today will be responded to via email at a later time, so please provide your contact details so we can respond to you. Today we are here to discuss urban stormwater management. When rain falls on your home, business or garden, it runs into your downpipe and into the nearest stormwater drain. The stormwater system is designed to prevent urban flooding by directing stormwater into the nearest creek, river. Lake. or bay. There are more than 300 stormwater outlets to Port Phillip Bay alone, as well as outlets to western port and many creeks and rivers throughout the state. There are two main challenges with stormwater: one, the large volumes of stormwater that run off hard surfaces such as pavements and roads and two, that stormwater carries pollutants like bacteria, litter, sediment and oil. Stormwater is the major cause of pollution of Victoria's waterways. Over the last year we've spent we've all spent more time at home. We've spent more time exploring our neighbourhoods and walking along local waterways and beaches. I think for many people this experience has highlighted the importance of protecting our environment from pollution and waste. Perhaps you've noticed litter or an oily sheen, pet droppings or even concrete in your local waterway. These are common pollutants you may find in our waterways. Other common stormwater pollutants you can't see include garden pesticides, harmful microorganisms from soil or animal droppings and toxic heavy metals. These pollutants can make our waterways and beaches unsafe for swimming and can seriously harm our environment in many ways, from nutrients causing excess plant growth that chokes our waterways to heavy metals and toxins causing adverse effects in animals that call these places home. This is a significant issue for Victorians. Every month EPA receives approximately 200 notifications from community members, of pollutants entering waterways via the stormwater system. Notifications include discharges to waterways that are coloured, cloudy, odorous and oily, sometimes associated with visible harmful effects such as fish deaths. Large volume stormwater flows present challenges in their own right by scouring stream beds, moving water too quickly away from where it falls and transporting pollutants from the land to our waterways. As our urban areas grow and our climate changes, the challenges on our stormwater system and how we manage stormwater will become greater and more complex. In a warming climate the benefits to community well-being of retaining water in our urban landscape is gaining increasing attention. Stormwater can also provide an alternative water supply suitable for garden watering and toilet flushing. At EPA our purpose is to protect the environment and human health by preventing or reducing harm from pollution and waste. The best way to reduce the impacts of stormwater pollution is to stop the pollution getting into the stormwater system in the first place. Community, business and government all play a role in reducing sources of pollution and waste to stormwater. As community members we can all help prevent pollution pollutants from reaching local drains and can improve our creeks, rivers and bays. Reducing stormwater pollution can be as simple as washing your car on the grass or a car wash that recycles water, always putting your litter in a bin, cleaning up after your animals and cleaning paint brushes in a sink so they don't contaminate stormwater. EPA is responsible for regulating pollution and waste entering waterways. We do this through environmental laws, policies and regulatory controls and by working in partnership with Victorian communities, water authorities, businesses and government. EPA undertakes monitoring of ambient and recreational water quality during summer as part of its beach report and Yarra watch programs. These help the community make informed decisions about swimming and other recreational water-based activities during summer. Sampling has shown that water at the bay and Yarra river sites meet the standards for swimming 98 and 84 percent of the time respectively. Stormwater pollution following rainfall contributes to not meeting these regular recreational water quality guidelines. EPA works closely with local councils to improve the environmental management of urban stormwater. Action actions such as water sensitive urban design, investment in rain gardens, sediment ponds and wetlands can improve the quality of stormwater entering our waterways. EPA works with local councils to provide them support and guidance on how to manage stormwater. In 2019-2020, EPA expanded its offices for the protection of the local environment or OPLE. This is a pilot to cover 23 councils with 19 EPA authorised officers embedded in our communities. The OPLE program has delivered fast responses to local environmental issues such as resolving noise complaints, reducing stormwater contamination and litter. EPA also works closely with the Department of Environment, Land, Water and Planning or DELWP, who are responsible for the broader statewide strategy for managing stormwater. Integrated Water Management where all sources of water are considered including stormwater is seen as crucial to make our cities and towns resilient and liveable for the future. Planning codes are also crucial with developers looking to the Victorian planning provisions for the rules they need to comply with in any development. For Melbourne, Melbourne Water in their role as catchment manager are responsible for the health of our waterways. Their recent Healthy Waterways Strategy renewed its focus on reducing the impact of stormwater especially in high value waterways. EPA continues to conduct research into many aspects of stormwater. This research includes investigating new sensors to better inform us in real time when pollution is occurring and better defining the sources of pollutants such as bacterial contamination at our beaches.

EPA is developing new best practice guidelines on urban stormwater management that will apply to more land uses such as commercial and industrial premises. A significant addition to the draft guidance is the improved flow standards which aim to reduce large stormwater volumes which flow off hard surfaces such as roofs, driveways and roads. This is an opportunity to include updated scientific knowledge of urban stormwater and bring the guidance in line with community, business and government expectations, and Victoria's new environment protection legislation.

As Victoria adapts to a growing population, a changing climate and a revised industry profile, EPA and the Victorian community are faced with more complex environmental and human health challenges including the protection of our waters from polluted stormwater. This updated guidance is essential to help improve the management of stormwater so we can protect our environment and human health from the impacts of pollution and waste. On this note I will hand over to our MC for this event, Leon Metzeling. Leon is a senior applied scientist in EPA's applied science division specialising in inland waters. He's been with EPA for over 30 years and has led the development of significant pieces of work to protect our environment and human health. Leon is leading the science input to the review of the best practice guidelines on urban stormwater management. He has addressed many aspects from stormwater in his time at EPA and continues to be involved in research on stormwater impacts. Leon has over 40 publications in the peer-reviewed literature focusing mainly on freshwater ecology and bioassessment but has recently focused on the impact of emerging contaminants on aquatic systems and human health. Leon has a wealth of experience and knowledge and has organised the fantastic panel you see here today. Over to you Leon. 

Thanks Carolyn. It's indeed my pleasure to be emceeing this seminar as I consider the broader issue of stormwater to be the major threat in our waterways and one that we have as a society have yet to address properly. People do have a complex relationship with water. While we recognise the crucial role it and the importance that water has in life and the premium we're willing to pay for having a view of water, we also don't want too much of it around you know floods are not a good thing and as Carolyn mentioned moving floodwaters away has seemed to be a priority. But there are consequences to this and consequences that have not been sufficiently well acknowledged nor acted upon. I suspect that stormwater has been a problem ever since people started ploughing the land and building houses but it's probably reached its low point with the quality and quantity of stormwater from our cities and towns. Now two of our speakers Chris Walsh and Tim Fletcher have spent many years looking at the ecological and physical aspects of stormwater and are well placed to talk about the problems and the solutions that we need to be thinking about and addressing as a society.

It is a big problem but I do feel that there is momentum. Some of the high level strategies in Victoria such as Water for Victoria, Integrated Water Monitoring Framework, Melbourne Water’s Healthy Waterway Strategy, they've all acknowledged their problem and uh coming up with ways to tackle stormwater the stormwater problem. EPA as Carolyn mentioned was is renewing our guidance and hopefully we'll be incorporating uh improved stormwater flow standards into the new guidance. Now while standards are important they'll come to nothing unless people adopt them and change their behaviour towards how they think about stormwater. And this is where the work that Stephanie Lavau our third speaker will be is is well placed to answer looking at the drivers of people's behaviour and their adoption or not of some of these the technologies we need to improve uh management of stormwater. So on that I’ll hand over to Chris um he'll be our first speaker to start us off by talking about what we need to do in order to protect our Victoria's streams and bays. We'll then move on to each of the next speakers in turn. I’ll encourage you all to start uh recording questions as as each of the speakers are talking and put them into the online system and I will they'll all come to me and I’ll ask them at the end of the session at the end of the speaking session. So with that I’ll hand over to you Chris. Thanks very much Leon and uh and thank you to Carolyn for the invitation and I   should start by thanking both uh both Leon and our colleague, Yung En Chee, at the University of Melbourne who were really the primary drivers of getting the three of us here. Today wouldn't have happened without you both so thank you. So um today I’m hoping to convince you of four things. Firstly that the State Environment Protection Policy objectives, SEPP uh the SEPP objectives for streams and rivers are pretty good uh they have a strong uh ecological underpinning and they are useful for alerting us to streams that have problems.

One of the major persistent problems for streams in many parts of the state is the current dominant approach to urban stormwater drainage practice which erodes, pollutes and degrades streams as Carolyn was uh was telling you. Current and even the proposed standards for better stormwater practice don't really cut it. Uh they're not adequate to arrest the degradation of the state's streams and they don't link to uh the SEPP objectives. However we have developed uh tested and implemented alternative objectives that are well accepted by the community that can protect and restore stream health and can be directly linked to SEPP objectives uh to guide drainage practice for true stream protection. So I’ll take you through each of these four points in turn. I’m going to anchor today's uh talk uh around reaches on four streams in the east of Melbourne uh so first a brief orientation now. I’m going to begin by contrasting three small streams that rise in the Dandenong ranges as they were 10 years ago. BRS is Brushy Creek, it's a degraded urban stream draining the suburbs of Mooroolbark and Croydon and about 25 percent of its catchment is covered by roofs and roads. Or at least they were in 2009 where I’m uh I’m drawing these statistics from. Uh Sassafras Creek SAS uh oops no in fact oh sorry no Little Stringybark Creek is where I’m going next isn't it. LIS it's also a degraded urban stream rising in the suburb of Mount Evelyn but then flowing into the rural residential areas of Wallan. At our sampling site that we've been sampling for many years about 12 percent of its catchment’s covered by roofs and roads they were in 2009. Sassafras Creek at last uh is a healthy forested stream that you might be surprised to learn is also an urban stream. It drains the uh the township of Sassafras and at our sampling site uh about eight percent of its catchment is covered by roofs and roads. So Little Stringybark Creek and Sassafras are both moderately urban catchments but they're in very different conditions. Sassafras is in very good condition, Little Stringybark Creek is degraded we'll come back to why that might be in a minute. I’ll also show you some data from YAR the Yarra river at Fitzsimmons Road Templestowe this site's downstream of these three sites uh three streams as well as downstream of Mullum Mullum and Diamond Creek that drain large areas lane so it's a good integrator of the story of these three streams. It's important to realise that uh that none of this area upstream of Fitzsimmons Road there in the Yarra catchment to the east of Melbourne have seen a lot of urban expansion in the 20 last 20 to 30 years not much urban expansion at all. Most of the urban growth has been infill development of which there's been quite a lot.

So the State Environment Protection Policy objectives for rivers and streams provide solid defensible targets for healthy waterways in Victoria. They've got a good basis in ecological theory and that is that biological communities that we find in our streams are the product of the quality of their dominant ambient conditions together with disturbances to those conditions. So in stream and river ecosystems this means that for most of the time they experience uh flowing water of good quality with occasional disturbances to the flow whether it be drying or flooding which then can then temporarily worsen water quality. So that's a natural condition for streams. So the SEPP uh objective the SEPP for rivers and streams has two types of objectives. First there's the water quality objectives and so here for an example we've got the uh the objective for uh the total phosphorus for uh for the Yarra catchment and there's a slightly different objective for lowland streams versus upland streams that you can you can see there. And we've got the actual 75th percentile concentrations for total phosphorus for our three streams here for Sassafras Creek, for Little Stringybark Creek, and for Brushy Creek. So a healthy urban stream Sassafras Creek easily meets the objective for total phosphorus whether it be considered an upland or a lowland site that's sort of on the on the border there. Our similarly urban uh but less healthy uh urban stream uh Little Stringybark Creek.

It's not being so remarkable now no come on you can do it um Little Stringybark Creek just fails to make the total phosphorus objective uh and the more heavily urbanised stream Brushy Creek doesn't even come close to meeting the objective. So these objectives are very useful for us being able to differentiate uh levels of degradation. The other type of objective is uh biological objectives and so this one is um uh so biological objectives assess the composition of species living uh in the stream, so they're powerful objectives because the in-stream biological community is a product of past conditions both ambient and disturbed, ambient condition and disturbances in the stream. So this is a SIGNAL score it's an index based on invertebrate families found in the stream and it tells a similar story to the total phosphorus objective. Sassafras Creek easily meets the objective, Little Stringybark Creek’s a borderline fail and Brushy Creek is a comprehensive fail. Now there are several lines of evidence that point to the primary cause of the increased degradation across these three sites being increased stormwater drainage impacts. Importantly the good condition of Sassafras Creek shows us that urban land doesn't necessarily need to cause stream degradation if stormwater runoff's prevented from flowing uncontrolled to the stream.

So if we uh if we look first at um at Sassafras Creek here. There's very little formal stormwater drainage in the catchment most of the roads drain informally to the forest like in this photo on the top left here uh or um to earthern drains that allow water to soak into the soils during most rain events. And most roofs drain informally to gardens or to rainwater tanks these increased flows from hard surfaces are adequately captured by the deep soils of the mountain ash forests of the catchment. Sassafras township itself does drain to a gully which is eroding and is looking uh a bit troublesome but that gully itself seems to be containing uh retaining enough sediments that it's still continuing to protect the stream. In contrast uh the catchment of Little Stringybark Creek looks like this more like your typical suburban landscape. Uh every drop of rain that falls on the roofs that you can see in this photo drain to pipes that flow directly to the stream. Uh same with the water falling on the road or for that matter the soapy water used to wash the car in a driveway on a sunny day. The conventional stormwater drainage causes erosion, pollution and uh flow disturbance that has degraded Little Stringybark Creek that that is making it look a less happy place than Sassafras.

We know that direct drainage connection between a hard surface and stream uh damages a stream damages the stream and effective imperviousness which is the proportion of a catchment covered by roofs and roads connected to the stream by pipes uh is a strong indicator of stream degradation. In the case of Sassafras Creek despite having eight percent of its catchment covered by impervious surfaces, it's effective imperviousness is near zero while Little Stringybark Creek's effective imperviousness is much higher and Brushy Creek’s is higher again. So what does direct drainage uh do to streams? So the primary focus of our past research has been on the way it changes flow regimes. These plots show the patterns of flow in Sassafras Creek which has little effective imperviousness and Brushy Creek which has a lot. And there's a couple of things to note about these so the scale is stream flow in millimetres per day so it's the depth of stream flow if you uh you divide the uh the flow in volume in the stream by the by the catchment area to get depth so it's similar to the way we measure rainfall.

So two things to note, firstly the impervious surfaces and sealed drains reduce the opportunity for water to drain into the catchment soils and so the result is that in Brushy Creek we've got lower base flows so when it's not raining we've got less flow in the stream. The connection to the drains greatly increased the amount of flow following small rain events say 1 to 10 or 15 millimetres and so we're seeing lots of very high peaks in Brushy Creek, not so much in Sassafras Creek. So uh so in in the natural catchments the response to small such small events is pretty small uh but in the Brushy Creek catchment large volumes of polluted runoff flow to the creek every time it rains just uh just a little bit. So effective imperviousness greatly increases the the frequency of both hydraulic and chemical disturbances to streams and that's the primary impact. And how so how does this affect water quality and specifically water quality as measured by the SEPP objectives? Well let's have a look. In streams uh pollutant concentrations are usually correlated with flows so each of the points in these plots is a single sample from the stream with its uh total phosphorus concentration plotted against stream flow.

sorry I’m having some technical difficulties here do you want to have a go changing that while I  continue. And so in each of these plots uh we've got a black horizontal line which is um which is the 75th percentile for uh for that for that uh that stream uh and the orange dashed lines are the uh the objectives for our 75th percentile and so you can see that Sassafras has a low 75th percentile, Little Stringybark uh intermediate and Brushy a higher 75th percentile. So and they are plotted against stream discharge at the so each point is plotted against um the stream discharge at the time of the sample and so in a healthy stream like Sassafras Creek rare high flows uh carry large concentrations of contaminants but for almost all the time during low flows concentrations of total phosphorus are low. This dominant high quality ambient environment makes Sassafras uh Creek a healthy environment. So you can see that in all three streams achieving or failing the 75th percentile concentration the uh which is the orange horizontal line is all about what happens during these ambient low flow conditions which mostly fall below the 75th percentile flow, that's the vertical black lines in each one of these plots. So in Brushy Creek and to a lesser extent Little Stringybark Creek, stormwater drainage systems raise pollutant concentrations during dry weather and every single time it rains— that's more than 100 times a year in this part of the world. So to protect the stream and to satisfy the SEPP objective the primary focus needs to be on reducing that frequency of disturbance, on keeping stormwater out of the streams during these frequent small storms that pose no flooding risk and keeping dry weather spills out of the creek as well as well.

So current as well as the proposed standard specify required reduction in annual pollutant loads from impervious services without reference to a targeted condition in the stream.

The implementation of these objectives over the last 20 years have really failed to arrest the degradation of our site on the Yarra River at Templestowe. 20 years ago it met the SIGNAL objective most of the time. Now, it now it does not. This declining condition has most likely been caused by the catchment’s infill development with stormwater drainage built under existing standards. I’ve lost I’ve lost my ability to uh there we are I don't know I think I must have sweaty hands uh. And the decline has been despite uh you know in the in the catchment upstream of Templestowe, this decline has been despite quite a lot of investment in the retirement and upgrades of sewage treatment plants upstream uh decommissioning of many septic tanks, lots of money spent on riparian revegetation, lots of money being spent on environmental flows stormwater runoff remains the major problem that's causing this degradation.

The annual pollutant load reduction targets were conceived to protect the Bay. Mean annual loads are the concentrations of flow over an entire year so they integrate over a really long period. That's useful for large water bodies with long retention times like Port Phillip Bay but it's much less of use for uh for dynamic variable systems like streams. They've never really done a good protect a good job of protecting streams. In 2012, uh we wrote this paper which uh provided a critique on the designs of stormwater control measures that have been built to achieve those load reductions, such as stormwater treatment wetlands and biofiltration systems. And we found them wanting. They generally failed to address that frequent flow disturbance problem allowing frequent storm flows to pass through them with little attenuation. More broadly, loads objectives don't provide guidance on the primary flows which should be targeted for stormwater management for stream protection. If we take Brushy Creek as an example, most of the phosphorus loads, so that's the histogram at the top here, are delivered by high flows above the 75th percentile flow and yet the primary need to meet our SEPP objectives is to reduce the concentrations in the more frequent small flows uh during dry weather during dry weather and uh following frequent small rain events. So let's say our objective is to reduce annual phosphorus loads by 45 percent. One possible option uh for doing this would be to completely retain runoff from all small to moderate rain events and remove most of the uh retain remove most of the water completely and release the remainder as well-treated base flow. This would be a good way to go this would ensure the protection of ambient conditions that the SEPP objectives are aiming for so that's one option. And here we go again

I can't do it thanks. However we could equally meet our 45 percent load reduction target by building a wetland that retains all flows for a short time, removes some of the phosphorus but has a prolonged release of water for uh with higher than base flow concentrations thereafter. It's a much less satisfactory outcome sorry I need to show you the less satisfactory outcome. So this is something like a wetland might produce, so you're still reducing your loads by 45 percent but you're um but you're really leaving those um those concentrations during the low flows unchanged or potentially even making them worse. Annual pollutant load objectives give us no guidance on which of these two very different options is preferable. If we're to protect stream ecosystems, we need alternative standards that encourage solutions like option A and prevent outcomes like option B that are likely to fail to protect streams. In 2016, we, Tim and I, together with a group of international colleagues developed a set of principles for stormwater management for the protection of stream ecosystems from which we developed an alternative set of stormwater management objectives for stream protection. Uh briefly our principles were that's interesting uh no impervious surfaces should drain directly to the streams as the primary flow path. So drainage pipes should be used for flood protection not for dry weather spill disposal. The drains shouldn't be the first place that water flows to. Runoff from small to as large as possible rain events should be retained to prevent uncontrolled flows to the streams. That is, reduce disturbance frequency. Runoff should be filtered and delivered to the stream in the volume, pattern and quality as close as possible to reference condition. To achieve each of these objectives, it's likely that you're going to need to uh reduce your total volume of runoff substantially. Now, in the proposed revision of the standards it's really on this this last principle that's been added—volume reduction. But this principle is the only one of the four that doesn't directly affect in-stream processes. We really only included this principle to emphasise that volume reduction is likely to be required to ensure adequate protection of ambient conditions and disturbance regime. The previous three principles are actually much more of much more direct importance. We aimed to test if such principles were feasible and acceptable to the community and effective at restoring streams. And so to test that we've used the Little Stringybark Creek catchment to build uh hundreds of stormwater control measures in partnership with the community and council and with Melbourne Water. We turned these principles into uh

into uh four uh indices that are averaged to produce a single measure of stormwater control performance, the Stormwater Stream Impact index. The four indices are um oh sorry each one of these indices is scaled between zero, meaning you're perfectly mimicking our reference or target condition, to one, where you're essentially doing nothing and it's like conventional drainage with water just going straight down there down the drain. So we have these four indices that make up the overall index. So there's RO, the runoff index, the runoff frequency index which assesses how often stormwater control measures overflow or bypass and scales it between the frequency of runoff without any stormwater control and the frequency of rain events big enough to produce overland flow over catchment soils in in the reference state. VR is volume reduction index assessing how much stormwater runoff's kept out of the stream by stormwater control measure. FV is the filtered volume index assessing the volume of filtered flows that are delivered at an appropriate rate. And WQ's the water quality index assessing how close to the SEPP objectives for TP, TN and TSS the stormwater control measure achieves. And S is the simple average of these four indices. We've tested the uh the acceptability of this performance standard and it has successfully been incorporated into

(laughs) sorry I don't know what's going on

all right see if you've got the magic oh oh Leon you've got it haven't gone too far I think you might have yeah good uh so I don't know I you had not too far

Beautiful thank you, I do apologise. So we've uh we've tested and trialled and implemented the this this in the Stringybark Creek catchment through an Environmental Significance Overlay which has been operating for um for five years now uh with broad community acceptance and support. And most importantly we found that using this sort of performance standard can restore streams uh from failing SEPP objectives to meeting SEPP objectives. The nice thing about the S index is that can easily be integrated into effective imperviousness. Uh the area of each impervious surface that's treated by a stormwater control measure is weighted by the fraction x S so with the addition of each stormwater control measure in our Little Stringybark  Creek catchment, we were able to, or at least in the northern tributary of Little Stringybark Creek which I’m showing you here, we're able to reduce effective imperviousness substantially from about six percent down to less than three percent. And the response we observed in the stream was consistent with our expectations based on that reduction. Uh without the stormwater control measures, the northern trib failed to meet the SEPP objective for total phosphorus but after implementation of the SCMs we successfully reduced 75th percentile total phosphorus concentrations to below the SEPP objective. And reasonably close to the concentrations that we observed in our forested reference streams the green the green bar on the right. So here we have a simple standard for stormwater control that's been tested, showing to be effective at stream protection and accepted by the community.  Its use of four indices means that there's some internal redundancy but also greater flexibility than solely relying on say the volume reduction uh to meet the standard. It's also more directly targets uh degrading processes of stormwater runoff than loads reductions do. So we're confident that applying a standard like this can truly protect and restore streams. And Tim's now going to tell you how we get there. Thank you very much Chris. Exactly, so Chris has set out what we need to do to manage stormwater in a way that we're no longer ubiquitously degrading streams which is what our current practice does. And so I’m going to try to outline for you what does that actually look like on the ground? What is it we're building? Uh and most of us if we know something about water sensitive urban design, we'll have a kind of picture like this uh in mind where we see all sorts of nice stormwater control measures I was about to take the laser and pointed at the screen here that would not have helped.

Nice sort of vegetated systems that receive stormwater and filter them and we've got some examples there, a couple from the Little Stringybark Creek project uh Chris talked about, a couple uh from a from a conference presentation in France and a Melbourne Water generic uh representation of it. So those things are all nice but those in themselves are nowhere near enough to do what we need to do. So I’m not criticising those but really if we want to achieve that outcome of not having frequent stormwater into our stream, therefore not having the hydraulic stress that that creates, not having pollution that that creates, we really need to start as Chris said, the prerequisite is we need to take a lot of that volume out and that all comes down to harvesting. Okay that's probably not the picture I should have used, that's a different sort of harvesting. We really need to be harvesting that stormwater. There isn't another feasible way to get rid of all that water. You might think oh we could just infiltrate it. There isn't going to be enough space in a typical urban environment to do that and indeed if we infiltrated that amount of water we'd have all sorts of unintended consequences. So we need to think about uh serious uh stormwater harvesting that can of course uh start at the household scale uh with you know rainwater tanks and more sophisticated rainwater tanks perhaps. Or at the larger scale but again, I  want to perhaps you know get you to think about the things we already do such as for example having a rainwater tank that we water our garden or perhaps use in a toilet. Those things are a great start but we really need to go further. There is a lot of stormwater and in order to meet those targets that Chris described we really need to deal with that volume. So we're talking about much more sophisticated and much more ambitious approaches for stormwater harvesting. Here's an example that Melbourne Water and Western Water are working on which is the Sunbury Integrated Water management Plan. It involves potentially it's a project in investigation at the moment and in consultation but amongst the strategies to be pursued are the idea of harvesting stormwater in a whole range of wetlands around that that growth area development around Sunbury and then

transferring that water where it will be then fully treated to potable standards and then injected into the potable network. And so here we're talking about a type of system where we can actually bring that stormwater volume that gets discharged to the creek down to the rate that it would have been naturally and that allows us to then use our other complementary systems to get that frequency of disturbance and that quality back to their natural level. But of course we're not all going to be able to build big scale systems like that everywhere but we can start to think about using technology to uh create rainwater tanks that are far more clever and sophisticated than currently. So here's uh an idea that Southeast Water has developed and we've been working with them to expand, where you have a rainwater tank that's connected to the Bureau of Meteorology, it's talking to the Bureau all the time, it's providing water to the house for a whole range of uses clothes washing, toilet flushing, gardening, potentially hot water in in certain situations but at the same time it's releasing a small amount of water uh to the creek, filtered water so that you sustain a natural base flow. And similarly maintaining the same flood management performance because when it sees a flood coming days before, it'll start slowly releasing water to create storage for that. So we have opportunities with technology to now create much more sophisticated ways of managing our stormwater harvesting. And if we think about where we could uh go with that and the next speaker, and Chris and I  so Stephanie Lavau and Chris and I  are working on a project with Melbourne Water and Southeast Water where we're combining large scale storages of water with rainwater tanks that will all be connected to each other and talking and releasing filtered water at the right rate at the right time of the year to for example, protect the habitat of platypus. And these are the type of what perhaps seems revolutionary but now really need to become sort of standard practice if we're to avoid the degradation that's uh ubiquitously occurred wherever we manage stormwater in that traditional way. What's really important about these type of systems however is that they involve interaction with people. So we're not just talking about now Melbourne Water for example being the only manager of water. We're talking about everyone with a household potentially having a rainwater tank that not only provides some of their water but releases water for the needs of the stream, holds back water for the needs of the stream and that's a really critical point. And so now, people become a part of the water management system in the same way that uh householders are becoming part of the energy production system with solar panels. And that's going to pose some really important questions for how people might be engaged in this process. So thank you Leon Chris and Tim. So now over to how will this work? So I  feel a bit like the end of a one of those childhood jokes, so we have a stream ecologist, an ecohydrologist and a sociologist go into a public forum and the uh the stream the stream ecologist says well we need to better manage our urban runoff so that we can better protect our streams and the ecohydrologist says well, here's a range of water sensitive urban design technologies that might get us there and the sociologist says well that's actually not enough, we need to be thinking about the social effectiveness of these technologies as well. We need to be thinking about what are the key issues and the key factors that are going to influence the capacities and the commitments and the understandings of community to be part of this picture of co-management. So I’m posing what might seem a bit of an odd question really, what might it mean to care for technology? And so I’m thinking about these kinds of technologies that Tim's just described, particularly these uh this real-time controlled, networked tanks. So three versions of what it might mean to care—so firstly, to appreciate or have an interest in something, to have an inclination towards something, would you care for a tank with your cup of tea for example?

Secondly, to give attention or serious consideration to something. We need to be thinking about how people are going to interact with, engage with and live with these technologies. We need to think about this from the moment we start to design these technologies through to their installation but even beyond that. And so that brings me to the third point here, to care for is to tend or look after something so that it stays in a good condition. There's a lot of insight on this that came out of that Little Stringybark Creek project that my colleagues have mentioned. It's really important that we think about what it is that needs to happen for those tanks for example, to be cared for so that they continue to perform in the long term because the story of this technology doesn't end at installation.

So a couple of key points of change that I see when we're starting to think about co-management of urban water. A couple of key points I'd like to highlight. So firstly, we're seeing a shift from using big infrastructure on public land, So for example, big dams, big reservoirs, to managing more what I  think of as micro-infrastructure for example, those tanks, those rain gardens not just on public land but also as Tim was suggesting, on private land and private land is becoming increasingly important to this story. And in doing so we're shifting from a centralised model towards a decentralised model of management because we have these technologies, this infrastructure scattered, distributed throughout the urban landscape. And that might indeed take us towards hybrid models where we start to think about how can we deal with those questions of control and coordination that might still be required in order to for example, coordinate an environmental flow for a waterway. Thirdly, we're seeing that we're layering domestic practices of water saving with practices of water retention and water release. So decisions that were made in a household that might have just been about saving water for consumption within a household actually become a lot more complex when you're making decisions that are also about how can you retain water to mitigate flood and release water for an environmental benefit. And so it's probably becoming clear this final point then that the role of private citizens, the role of community, is no longer just about using water but also about being producers of water. Tim was using the analogy of solar panels on the rooftops the way in which householders were no longer necessarily just users of energy but also producers of energy, So there's a parallel here. And when we're thinking about what it might mean to manage water as a householder, it's really interesting to see the way in which we've been affected by the millennium drought. And the ways in which increasingly we find ourselves managing our water use very consciously and planning our water use quite intensively in households. And so this comes from a bit of research we did a couple of years ago in the inner Melbourne area with people talking to us about their experiences of water in their household and we framed it quite broadly, we want to know what their experiences of water were and their responses were predominantly about an intense micromanagement of water for water saving. And I  use that term micromanagement with acknowledgement of geographer Lesley Head and she talks about domestic water practices. So you can see here quite a list of different kinds of practices in the household that people talked to us about and it comes through really nicely in this quote where this woman's talking about on the one hand, how often they wash their children and on the other hand, collecting the rinse water from their vegetables to throw into the garden there's this real intensity and planning and attention that you can read into these stories of how people are already managing water within their house. But as I said this is about saving,

about saving water and we're looking at much more complex decisions now for multiple benefits managing water for multiple benefits, So I'd like to finish by pointing towards three key challenges I think we need to address if we're going to move forward with these models of co-management. The first one is the question of the invisibility of water infrastructure. I was just looking behind us here, there's road building going on, I don't know if you've heard it behind us. Infrastructure the uh the urban backstage if you like to our lives. A lot of this infrastructure is hidden from view so in the case of water it might be within walls, behind buildings, under roads—we don't see it and it's out of our mind. And when we talk to people about water infrastructure in the city you get a lot of question marks. I don't know if you can see it well on that little drawing on the left there but essentially this participant in our focus groups was saying, you turn on the tap and water comes from nowhere and it goes to nowhere and she had a little question mark about the entry and exit point of water into her apartment. So water, something that somebody else has predominantly perhaps taken responsibility and we didn't even really need to be aware of the infrastructure and we only tend to think about it frankly when it goes wrong. And then shifting towards perhaps the right-hand side there, where we might need to take really seriously the question of how can we support people in understanding the built environment as an urban catchment and a lovely drawing there from another participant who's thinking about the rainwater that falls on her roof and where that flows through the built environment.

So to the second challenge that I think we have, that of fitting or refitting in this case water tanks into the home. And we're not thinking about fitting I’m not thinking just about the physical fit that is a really important issue how can we find enough space in an already crowded uh domestic environment to put a tank. Do we even have ownership of our home that we can make such a decision? I’m thinking beyond financial fit these are important questions too, the costs of tank and of maintenance and also how we might design particular economic incentives to help make that financial fit to get these technologies into domestic settings. But I’m much more interested in this—the fit with domestic practices. What is it going to mean to live with these technologies to live alongside these technologies and interact with these technologies particularly, as you've been gathering now where the role of these tanks becomes quite multi-purpose and that we're asking of people to be involved in decisions for a public good that's coming from their private space.

It's the third and final one—trust and I think we've got legacy here that we have to acknowledge particularly coming out the millennium drought and uh hearing stories from some of those participants I mentioned earlier who really have invested a lot in what they've done around their homes in terms of water saving usually for personal consumptive use. And sometimes the feelings of frustration and futility where you see bad practice elsewhere around you whether that's the person that's hosing down their driveway or washing their mountain bike the soapy water down into the into the stormwater or whether it be you know reporting a water leak on public land and nothing happens and you still see that water draining, draining down the road. So there's trust the others around you are doing their part. Then there's trust about letting people into the home because what we're talking about here in these kinds of solutions really blur those boundaries between the public and the private. Trust in letting people into your home and I mean both metaphorically or virtually, as well as physically so obviously physically in terms of things like potentially gaining access for maintaining technologies but also remotely or virtually through some of these technologies that we're talking about where you might have a device that's making decisions for you that might require access to data about your water use for example. And then finally trust in terms of believing in an ongoing and collective commitment to this so that this isn't just a flash in the pan but actually as I’m saying a lot of this is around thinking through the long-term performance. So trust that all this effort that you're putting in or this this change that you're managing is actually part of a bigger ongoing commitment. So just to summarise. So we've come to the end here and I suppose my argument is that it's really important that we think about the ecological effectiveness of these technologies and how well they're benefiting our streams. It's really important we think about how well the they work technically. But we also need to think about the social life of these technologies. We need to think about what it might mean to care for these technologies in the current moment but also well into the future. We need to think about the ways we which these technologies fit into private lives how we're going to live alongside these devices. We need to think about the distribution of responsibility in co-management and by that I don't just mean between people but also between some of these with the smart technologies themselves having responsibility. And we need to think about the social relations of urban water management and the ways in which these technologies make new relationships whether that’s between actors within urban border management, whether that be between the private and the public or even between communities and their waterways themselves.

Thank you. Well thank you to all three of you um with some really stimulating thoughts and um and topics there. And questions are coming in but I’ll um take my uh opportunity to ask the first question um to you, Stephanie um like you mentioned the millennium drought and that brought a real focus to people and onto the management of water and sort of harvesting it carefully and using it carefully. You know I was conscious of doing that myself and I think I was starting from a pretty high level of awareness. But what about what's happened since? You know like to my mind you know once the rain started falling um a lot of the impetus or desire maybe or the awareness has gone away. Is it is it something that how do we keep up that level of focus and awareness and care, I guess? It's a question from you rather than from the floor is it? Yeah. It reminds me just to tell a little story uh I left Melbourne back in 2009 to go live in the UK so it was just at the end of the millennium drought and then I came back seven years later and it was really interesting to meet my colleagues and hear a totally new story about water. So I'd left in this moment where it was all about water saving, water saving that's the big thing. And then coming back and hearing well actually the biggest threat to our urban waterways is stormwater and so it is really interesting because I  think the millennium drought you know, I  don't want to say we're indoctrinated but we were so carefully um engaged with water saving as a frame for what we do in our homes and I  do think that a lot of those kinds of practices and technologies and things are sort of they're dormant waiting and when we have focus groups with people about experiences of water in the home they are often referring to ongoing commitments and still having these technologies around, the water saving devices in the showers etc ready uh you know to jump into action. But I think that actually when we're thinking about urban stormwater it's a real challenge for us because it's a whole other layer of decision making that has to go on it's a lot more complex, you're making decisions in your home now not just about how to save water for your consumptive use but how to retain water to stop floods and how to work with water in a way that's going to be more beneficial for our urban streams. Could I just make the observation that I didn't see a huge difference between the millennium drought and after the millennium drought because uh even during the millennium drought there was way too much stormwater. Stormwater was still a problem it still rained during the millennium drought uh maybe 90 days a year rather than 100 days a year and uh and that was still a frequent disturbance to our streams and so uh and if we look at the volumes of water that fell during the millennium drought uh the amount of excess stormwater runoff in Melbourne's uh in in the Melbourne area still was uh was about the volume of water that we were importing from our reservoirs for our use so um. So it gives you a sense of the opportunity. There's a real shift in the attention though. So the way in which now in the last 10 years or so, that stormwater is really rising, rising up the agenda. Well there's a question from the from the audience which is quite an interesting one. If um if private citizens are considered as producers of water does that also make them liable for the excess discharges to waterways? I would like to see as far as I’m concerned you know we need to start thinking of stormwater that runs off an impervious surface that you've built by building that impervious surface if you connect that directly to the stormwater drain then you have become a polluter. And I  would I  would like to see some incentives, regulation, something, that would give uh it would make people think that uh well there's an alternative way, I  don't actually have to have this connected directly to the stream, there are lots of benefits for doing it a different way. So like a follow-up question from this question though is could there be an introduction of a stormwater levy? Now we do pay Melbourne Water part of our rates as something to do with stormwater so is that in effect some sort of levy? Or would there be a different fee? You know if you're generating a lot of stormwater, you pay for it. Yeah, actually, it um I feel like the dichotomy between wastewater and stormwater is really interesting isn't it? Wastewater we’re charged broadly based on how much we produce. It's a little bit vague it's based on a ratio of your of your use of potable water and that's assumed to be wastewater but broadly the principle is you pay for the amount of polluted wastewater you produce. As you say there's a waterway management uh charge or parks and waterways charged in different parts of Victoria it's got different titles and there's different amounts. But none of them give you a performance incentive to do exactly what Chris described—to reduce the amount of stormwater you produce, to manage it properly, to treat it properly, to do all of those things. There are many places in the world that are trying to do that and are doing it successfully. But it's here we do so little to make people aware of the impacts of stormwater other than just you know to them it just looks like a tax because it doesn't matter what they do to their stormwater they'll still pay the same amount. And a levy's only going to work uh if that levy goes towards treating your runoff from your property further downstream and in many cases that's not going to be possible in which case it doesn't make a lot of sense. A question from Liam from Bendigo. Community co-management is an interesting premise however is the water industry ready to share power and responsibility with the community? And if not, what barriers may exist to realise this opportunity? Any? So I  actually think that we don't know a lot of the answers to a lot of these questions around co-management I  felt when I  sort of set it up a bit as the three people walk into a bar joke I  was very conscious of the fact that I  don't have a punchline but actually I’m raising more questions than answering because I  think we're actually now in the space where we will be figuring out what co-management might mean in practice because there are lots of different ways that we could go with this. And I  think that coming back to the previous question about what it might mean for community to be producers of water and you know, we've used the solar situation as a bit of analogy but actually the stormwater situation is even more complex than that because it didn't doesn't require the kind of coordination that we need for urban stormwater because it's one thing to have these bits of infrastructure distributed and to be sort of managing them in different places but we're actually also thinking about how to control and coordinate them for particular outcomes. So it is I think a very complex domain, really pleased we've got um you know some excellent partners that we'll be working with on this Monbulk Creek project. Because it does sound like you guys have worked with water authorities so it sounds like there's a willingness and interest. And of course yes and certainly I think Melbourne Water are certainly giving this a red hot go with their Healthy Waterway Strategy which is very heavily co-designed with the community and partners and so uh they're giving it a crack but as uh as Steph said there's lots of lots of unknowns it's uh it's a pioneering approach. And I might just make a quick plug for Southeast Water because I get a commission each time I  do no joking

but you know they developed that tank-talk technology that allows you know these tanks to interact with the Bureau of Meteorology and to be operated adaptively and they are they've developed a whole technology division that's trying to do this. And I would say of course there'll be some industry players who say no, no, no, we're the centralised water provider and that's how it shall be forever. But I think there are others like Southeast Water who see the future and realise just as in the energy game you either see the future and try to create it and then you have your role as a technology provider and uh or you sit there and wait for other things to come over the top of you so I  I’m not as pessimistic as Liam from Bendigo that uh that the water industry uh is not ready. I think there are uh certainly members amongst them and who are really pioneering and I  think that’ll take the rest. And overall I would argue the water industry in Australia is pretty innovative and um and creative. Well maybe it's a related question but um building some of these requirements into our planning systems or codes I don't know what you've got if you've got any experience or able to comment on embedding some of these requirements into the planning codes and pluses and minuses, the difficulties, and or whatever? Well we've certainly uh trialled with our Environmental Significance Overlay in Little Stringybark Creek we've we have got these sorts of requirements in, in the planning scheme for a very small part of Melbourne. Uh it's we've had a few teething problems but generally I think we'd rate it as a success and certainly uh well accepted by the community and uh yeah the proof is in the pudding of the streams where we have shown a response that we'd hoped we'd see. Does that adequately answer the question? I  suppose I'd also point to the issue of compliance. So it's one thing to have provisions at the planning level but you also need to be putting resources into monitoring compliance with those planning regulations and that's something I feel really could do with a bit more work. Yes indeed. Um now a question from Jacqueline who's interested to find out a bit more about the Stringybark Creek project which used a range of mechanisms. Were any of them more or less effective than others? Was it more impactful reducing runoff volume or in partially treating stormwater? Any further impacts of these on improving stream health? Good question Jacqueline. Uh so of course I had to give a very abbreviated uh story of Little Stringybark Creek and I  showed the results for the northern tributary of Little Stringybark Creek where we have shown some success and we have uh successfully reduced um uh reduced runoff frequency as we'd hoped and uh and that was because in that northern tributary we did have a large harvesting scheme. Um in the other the other tributaries of Little Stringybark Creek we've been less successful and uh and I put that down to two difficulties uh well two primary difficulties. One is a lack of space, so we're dealing with a with a an urban area that's already been planned and uh and there's an infuriating number of stormwater pipes in the Little Stringybark Creek catchment uh that drain through people's backyards uh you know so you've got people's back fence and then and then the stream and so there's no space to put systems at the bottom of uh the bottom of pipes. And so so it's a planning a planning problem in the existing fabric that was a was a very much a difficulty. And then our second problem was a lack of demand. And so you know we put in heaps of rainwater tanks and literally hundreds and hundreds of rainwater tanks or I think over a thousand actually uh of rainwater tanks but even with those systems that wasn't using enough as much water as we require. And so um uh so I guess to answer, it's a long way around to answering Jacqueline's question, I think we have shown that uh you can be most effective where you can keep more water out of the stream, where you do have enough demand to keep water out of the stream to allow your filtration systems to work more efficiently. Yeah okay. And that harvesting has to be for users that are taking water right throughout the year. The classic thing we're all used to is a rainwater tank that you use for watering your garden which means it runs out of water in summer when you want it and all of winter it's just overflowing and going straight into the stormwater system. So our systems that supplied toilet flushing, provided clothes washing, provided hot water with appropriate treatment and in one case provided a car washer in a petrol station, those work really well because every day that tank's getting drawn down. So having a range of options is really good. Yeah. And we used a lot of leaky tanks as well so with tanks that had deliberate leaks in them that so that they were just leaking to the garden at a very low rate so that they were they were drawing down even if there wasn't a lot of use in the house. Now continuing on with Stringybark Creek um a question from Harrison from Sydney. Um did you see a change in the ecological indices uh in relation to the work there? Uh that is as yet an emerging story uh it uh we haven't done the full analysis on our biological data yet but I think looking at the data uh no we haven't seen as big a change in the biological community as we'd hoped. Um did you apply your stormwater index to that? Yeah that's right but um uh so so in the northern tributary where we would expect to have seen a change it does look like we're seeing greater abundances of sensitive taxa, sensitive species. So that's good. But what we're not seeing at all uh recolonisation of missing species. Right. So we're not getting uh not getting recruits in uh which is a bit surprising because it is pretty much a forested landscape around Little Stringybark Creek so I would have thought we'd have lots of potential for recruits but we're not seeing it. So when it comes to measures like SIGNAL which are all about presence or absence of families, we're not seeing a change in SIGNAL because we're not getting those new species, we're just getting changes in the abundances. So um it's a bit early days to be making strong conclusions on what's happened there but uh but initially we haven't yet seen strong ecological responses. Yeah and like I guess you know streams can be impacted in an instant but can take a long time to recover. Indeed. So we've got to allow some lag. Yes, yeah so but at this stage we're looking at a five-year lag and not much has happened, so we shall see. Um Harrison's question from Sydney has prompted me to think about um is Sydney or any other Australian city doing better than Melbourne? Can we stir these competitive juices? One for you, Tim. I...I don't have a strong sense of this I get asked this question kind of all around the world in a way and I always think that

there's lots of good things happening in lots of cities so Melbourne often gets described as a leader mainly by Melbournians I find and so I’m not that convinced of it you go to Sydney and see some really creative, interesting things. I work a lot in France and there's some really great stuff happening uh and I  think there's some great stuff happening here. So yeah I can't really and Brisbane's got heaps of great stuff, Western Australia there's a lot happening so I think you'll find really good innovators in water sensitive urban design um yeah all around the world and we should jump on their wagon. Yeah but I think what we're missing all around the world, including Melbourne uh are these sorts of technologies uh in fact I feel like I’m overstating what they are by calling them technologies. A lot of the time it's really just you know not putting in a stormwater drain if you don't really need it. But uh what we're not seeing are these sorts of solutions being applied at a catchment scale anywhere in the world really. I  mean Little Stringybark Creek is probably the first case where that's been tried. Sunbury is another example. In Sydney, South Creek they're working hard to do things right in South Creek but that's a much bigger catchment with much bigger challenges and so yeah. And there's some promising things around the aerotropolis in general and the Western Sydney aerotropolis. I  suppose just to complicate it a bit when we're thinking about who's a leader and who's not a leader, which city does you know better, it's really important that we're constantly asking that question of what success is and how we define success. So there’re competing stories that can be told if you look at Melbourne and think that we're a leader if you're thinking about you know the number of installations that there are in the urban landscape. If you change the question and you think about well what's the functionality of these things that have been installed? How well are they performing over time? Then you might get a different result. So it's really important that we constantly ask that question of what is success. Very true. Uh one question which I have is um you know we’re also encouraged to recycle water and we uh treatment plants do a good job of recycling water and I’ve often heard it said that reusing recycled water is in competition with reusing stormwater or doing something with stormwater. Do you have a perspectives on this? Like are they complementary? Are they in conflict? They potentially can be in conflict I think uh ultimately the volume of stormwater we want to be keeping out of our streams is pretty much the same as the as our demand. And so if we were serious about finding an alternative water source I'd say we should be putting stormwater first and to date, in many places that hasn't happened. It's wastewater that has come first I think at the detriment of uh of stormwater um perhaps there are circumstances where they needn't be in competition. Well it actually it makes me think about that the big picture planning uh as well. So that the concept you're describing Chris, is where we're trying to retain and use that stormwater within the urban landscape but if we had more of a European style of development where we had, I’ll call it “village” but anyway, urban centre surrounded by agriculture then we could potentially harvest all of that stormwater and combine it with wastewater to meet those very large demands for agricultural water that would have huge advantages for the resilience of our agriculture as well as kind of effectively deal with that conflict. But the way we have it now of this sort of, you've got this Melbourne that just grows out and out and out it's impossible to do that and then we do have wastewater and stormwater directly in conflict—you just can't find enough uses for all that water. But it of course that does raise opportunities for our regional cities. Yeah. Uh which of course the uh the stormwater standards are about as well, it's not just about Melbourne. For sure. Actually just immediately following on for that is is there any difference between Melbourne and cities like Ballarat, Bendigo—is the nature of the problem different?

The only thing I would say is that downstream of towns you give Ballarat and Bendigo as the example downstream of those towns you tend to then have rivers uh well you don't tend to, you do have, rivers flowing through agricultural land use and there's expectations about there's a there's a demand for that water. And so then you potentially get into conflicts where for the stream the best thing would be to hold that water back but agricultural water users may want that because they might rely on that harvest for winterfill storages so that can be a bit of a complication. I did gloss over our first principle, in fact, I  didn't even mention our first principle from our from our Principles paper which was uh decide what it is you're trying to protect first. And if your urban area is flowing directly to the coast, then all our arguments about streams and rivers they don't really count and your loads objectives are going to be fine. So for somewhere like Warrnambool for instance, uh where it's either the southern ocean or the Hopkins estuary uh there's probably a certain set of objectives for them. For some of the smaller streams that flow through Warrnambool then you'd be you'd be looking at different objectives if if you're interested in say you know, saving or protecting those streams. So it's all about your receiving ecosystem I would say. There's been a big influx of questions I’m trying to keep up with them. But somebody's asking, I'd like to know how micromanaging decisions can be made. I agree with the importance of thinking about trust from households to people and agencies managing their tanks remotely but what about trust from Melbourne Water and other agencies to the households and their micromanaging decisions. How are differences in criteria for decisions? How would they be negotiated? Well can I just put question mark, question mark, question mark uh you know I think as Tim was saying this really is a pioneering field and I don't think we necessarily have the answer to a lot of these questions. But I suppose to me it's a question firstly of what are the different options for the way in which the decisions get distributed. So as I said part of that's about people's decision making. Would that be in the home? Or you know Melbourne Water in the office? But also about the decisions that you're embedding within the technologies themselves. Yeah, it becomes much more complex doesn't it? As you know like comparison with the you know solar and stuff I thought yeah putting electrons and then they go along power lines it's kind of simple. But um here it's you know there's a lot more steps along the way, a lot more pathways and there's ecosystems to protect. Especially when those multiple benefits we're talking about wouldn't even necessarily line up in terms of what decision you should make in a particular moment in time.

I hate to be the kind of economist in the room but I suppose a market economist would argue if you send the right price signals you'll broadly get the behaviours you want. So if for example rather than just having a straight you know waterway charge or parks and waterways charge you charge people for stormwater management in the way you do for wastewater then there's already a behaviour. If you then reward people with tanks for their for example releases of environmental flows to support platypus in the same way you reward people for their release of electrons to support the grid then you start to get the behaviours that you want so um yeah I’m not sure I’m a market economist by mind but I  you know I  think there's yeah there's a fair argument there. Okay a question from Simon in Melbourne um a lot of the examples you gave was about nutrients and mitigating flows what about other contaminants in stormwater um to improve ecosystem health and can you comment on that? Yep sure, so um so I think we go back to the uh the premises behind the SEPP objectives really you know we've uh we've settled on a small number of pollutants that can be surrogates for a large number of pollutants. And so um stormwater the pollution problem in stormwater is extremely complex uh and so there's a recent paper by uh Sujay Kaushal and colleagues from Baltimore and the US that they called um or something about uh you know the cocktail the cocktail of stormwater pollutants and uh and they list and it's literally hundreds and hundreds of pollutants that are associated with stormwater. And you know if we start thinking about you know each one of those it really and thinking about how to manage this pollutant or that pollutant it really becomes an intractable question. And so you know the cleverness behind settling on things like total nitrogen, total phosphorus uh and total suspended solids for instance, is that uh particularly um phosphorus and suspended solids are good surrogates for heaps of pollutants that attach to particles. And so so if we manage for phosphorus, we're probably doing a good job for a whole lot of the other sorts of pollutants. And uh and then nitrogen is predominantly uh nitrate which uh it doesn't attach to particles very well and flows through flows through soils and so forth for more mobile pollutants, nitrogen is a good a good surrogate for those. So uh so our view is that um that if you manage for those pollutants uh you you're likely to be doing a good job for the general bulk. And of course the more obvious solution that we push number one is keep the water out of our system altogether. If you're keeping the water out, you're by definition keeping all the pollutants out. All of them. There's a couple of I think related questions from Teresa from Melbourne and Caroline from Melbourne about a lot of the emphasis has been on water harvesting and planned release from domestic areas but you know applying this same surely the same sort of thinking should be applied to sports grounds, schools, airports, freeways. I assume you'd all you'd agree with that? Or? Yeah, completely yeah I definitely would have covered that. I had 10 minutes but three of it was stolen by Chris. True. With my permission I might say. And my technology… 

Um but yeah really fair point so we're trying to create a sense of what's possible uh just with a couple of examples but I agree it should be everywhere. In fact, it should be the standard practice in the same way whenever we do anything that involves wastewater, we deal with it. Yeah. And if we had the same attitude to stormwater whenever we produce stormwater, we deal with it. So yeah absolutely, airport, runways, sports grounds, car parks, dog training facilities, everything. What about um Dale from Melbourne what is the single most important question sorry, what's the single most important change to policy or legislation which we could make to significantly improve stream health? Which I assume in the context of stormwater. Dale, that's a very difficult question. Do you want to go, Tim? I’ve got to guess at the surname,

Well I  would say the single and actually this really you should have taken up this uh Dorothy Dixer question, I think. The single most effective thing we could do I think is to implement those objectives uh statewide including having them included in the Victorian Planning Provisions uh in the same way clause 56 imposes and now clause 57 too I  think, imposes those load reduction targets. So if basically every development had to demonstrate that it maintains the runoff frequency at the current rate, it maintains the runoff volume at the current rate, it has the same volume overall runoff volume and that the water quality concentrations are the same so we uh meets the SEPP. So if that was a requirement of all planning through the VPP and exactly as uh Steph said that, that goes all the way down to the plumbing inspectors etc the building inspectors so that when you get your building permit it's uh complied with. Then that would absolutely change the world. Well would change Victoria yeah. yeah from Melbourne There’s two games here, there's the there's the short game and the long game. And I think the short game is about protecting those catchments and streams that haven't been developed yet. So the green greenfield areas where we're draining to streams that are still in good condition and we desperately need good, strong planning law to make sure that those new systems are those new developments are built in a way that that are not going to degrade our streams and we're having some success in places like Sunbury and in less success in others. And probably more less success than some success.

But the longer game is the existing urban fabric and uh and yeah we've had a crack at restoring Little Stringybark Creek and had a small amount of optimistic success there but it was quite expensive. It was a very expensive experiment that we that we ran and you really couldn't roll out what we did in Little Stringybark Creek across Melbourne to look at look at restoration in the next few years. And so what we what we do need is to say take a 50 to 100 year look into the future and say, what could Melbourne look like in the uh in a hundred years? And if we think about how often building stock and road stock gets turned over it's something of the order of 50 or 100 years. And so in 50 or 100 years we're going to have a completely new urban fabric here. We need strong planning and building regulation now that will incrementally reduce that that urban stormwater problem over the next decade next decade so that in 100 years time perhaps we can be looking at a healthy Gardiner's Creek, a healthy Darebin Creek. It's interesting that we often say, oh for pristine areas let's have strict targets but for you know our inner more inner areas they're already gone so you know let's not impose too much. I sort of get that but on the other side, we're basically saying in a hundred years we don't have an aspiration for them to be any better than they are now and that seems a bit unjust on future generations because if they want to recover it we're asking them to not only undo what we've done today but all the stuff that's going to happen in the future.

One of the questions which I hear about occasionally is that you know in a warming climate, less rainfall, higher temperatures having green and blue spaces in our urban landscape is going to become really important for humans let alone ecosystems, Have you had any experience with this or can you know think about the benefits from you know such developments are from a human perspective. I think we'd class that as a Dorothy Dixer.

I’ll start. Yes so I think it's a really important point and um actually Steph and I were having a conversation before about you know whether people are engaged by the conversation uh about stormwater. And um and I  think in the stormwater industry a lot of people have tried to actually connect people to those more human benefits that water in the landscape, supported vegetation, trees, shade, you know you walk down those lovely streets of Toorak thinking oh yeah I  might buy that house, and that house um and it's the trees that make those streets so beautiful and it's water that's necessary to support those and so I  think it's absolutely true and yes it's the thing that will probably get decision makers on board too so it's you know it's kind of got a political advantage. But it is so fundamental if you think about the most vegetation depauperate suburbs in Melbourne, they really are uh very uncomfortable places to live during you know those extreme heat periods. And I think that's a very significant moral choice for a city to make to leave uh you know some areas like that. And stormwater presents a really great opportunity through passive irrigation etc to create these landscapes that reduce heat stress, reduce therefore the loading on the health system you know there's lots of data about that. As well as data on effects on people's you know mental health. Yeah that's what I was going to add as well so those physical well-being aspects the we have colleagues who work a lot on the mental well-being that is associated with being near these blue-green spaces. Yeah. In our Principles paper we uh we spend quite a bit of time on you know going through the various co-benefits but we do we do signal a warning that uh we really need to keep our eye on stream protection and restoration. And if we if we design our stormwater management to protect our streams we're going to achieve these co-benefits. Often if the co-benefits come first, the stream can still be clapped out. So uh. Okay. Yeah we have to the question is what are we trying to protect or what do we do you know keep the focus and be clear about it anyway. Yeah I think we're running out of time but uh one final question from Ross um in the water industry we are finding that cost prohibits us from creating larger centralised stormwater harvesting systems i.e. other forms of water are cheaper to produce. Where do you think we will have to go to make this an option that water authorities will accept? Sunbury. So a case study in other words. Yeah yep and I believe the uh the economics of Sunbury stacked up you know so it was the first thing they um they assessed and uh and so harvesting water from Sunbury was cheaper than other options. Yeah okay that was the first box ticked in that case. But of course it's not going to it's that is not going to be the case everywhere. So yeah because it's a long way from the sort of dominant sources of Melbourne’s water. But again I think if we if we start to think about how are people charged for the way stormwater is managed you know in in wastewater treatment we don't go, oh it's too expensive to build a treatment plant so we won't. We say we need to build a treatment plant so we need to be charging appropriately to be able to afford that investment to protect the environment. If we thought about stormwater in the same way we could easily then say you know a lot of individual houses aren't going to be able to treat stormwater the way they are required to but they could contribute in the way they would for wastewater to a fund that then funds a a regional scale harvesting system. Okay. I think we're coming up to the end I think there's just a minute or two left. I’ll just um finish up by saying thanks to everyone um as Carolyn mentioned you know EPA gets lots of pollution um calls about uh the stormwater system delivering pollutants to our waterways. So often EPA’s at the pointy end of acute events trying to manage that. I’ve been involved in a couple in recent times which present quite different uh aspects because of the stormwater system. Everyone probably remembers the big fire in the western suburbs which the chemicals were there and it took a long time to put out and it was also about 10 meters away from Stony Creek and this fire water went into Stony Creek it was a real toxic brew. And it was terrible. You know and had immediate, severe long-lasting effects. Now there was a similar fire up in the northern suburbs about a year later um not identical case study nothing they're not you know there's difference in size but still a chemical warehouse fire but um the stormwater system was effectively disconnected from it went uh about 750 metres to a wetland which could be switched off. So a constructed system and water could be stockpiled in the in the wetland and then pumped to sewer. And Merlynston Creek was the closest creek and had basically no impact. So you know we talked about urban renewal and I think you might be lovely if that sort of system was in place so that in future um these high risk sites you know aren't in the Stoney Creek situation but in the Merlynston Creek situation where they're at least given a chance because accidents will happen. And of course in the longer term hopefully we'll have the more ongoing uh benefits and controls that you've talked about a lot and researched a lot in order for that longer term uh benefits to our streams and the overall environment. So I’d like to finish up by thanking the three of you for a really good stimulating talk. Um like to remind everyone who's listening that the next EPA Environmental Science Seminar Series will be in May. It's going to be on climate change and environmental public health so maybe some overlapping stuff we've talked about today and so I hope you all sign up for that. We have been capturing the questions I haven't been able to ask all of them. So we'll try and get back to the people who posted them uh with that with answers. So thank you again everyone and I'd like to thank our speakers once more, thank you. Thanks, thanks Leon.