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Showing the basin from the top with part of the swale in the foreground

On a steaming hot day last October we went to see the recently completed Johnston Street Bioretention Basin at Earlwood & go for a walk around Illoura Reserve.

The bioretention basin was much larger & more interesting than I expected.  The bush at this location was also a surprise being quite different than other areas of Wolli Creek that I have walked.   The trees were gorgeous. Towering Red Gums & Turpentine trees lead into the bush & the dreaded Privet was blooming so the air smelt nice.

We went back again today just to see how much the plants in the basin had grown after all this rain we had.  It was as expected, lush & green. What wasn’t expected was all the work done by the volunteers of the Wolli Creek Preservation Society.  Signs say they are regenerating the bush around the basin. They had opened up a pathway that allowed us to walk right around the basin & up to the Red Gums.   It is so nice being in bushland. That it is so close to Marrickville LGA makes us very lucky in my opinion.

Red Gum - there are many great trees in this location

I had not heard of swales & bioretention basins until after starting SoT, so here is a brief rundown of what they do & some stats about this particular basin.  A bioretention basin is constructed to manage & clean stormwater before it enters creeks or rivers.  Stormwater enters our waterways at a terrific pace. This can erode the bank in places, but also erode the bottom of the watercourse.  Stormwater also delivers an enormous amount of pollution to our waterways – nitrogen, phosphorus, heavy metals & fine sediments.  All these have a detrimental effect the water quality of our rivers & creeks.

A bioretention basin is really a scooped out landscaped area of land that can be big or small.  They generally contain 3 layers: course sand or pea gravel at the bottom, another layer of sand in the middle & sandy loam at the top.

The idea is that stormwater from our streets is directed to the bioretention basin where it literally percolates through these levels.  This not only slows the stormwater, but it also cleans it of oils & other substances that comes off our roads.  The cleaned water is either allowed to seep naturally into the ground to make its way to the river, or channeled via a pipe or pipes at the lowest layer as it is in this case.

Finally the surface of the basin is planted with native grasses & small shrubs. The plants need to be able to tolerate water as well as periods where the basin is dry.  Swales work on the same principle, but rather than a shape of a basin they look similar to a rocky creek bed.  The Johnston Street Bioretention Basin also includes a long wide swale running downhill beside the basin.  There is a large pipe that directs water from the basin to the bottom of the swale.

The Johnston Street Bioretention Basin, built by Sydney Metropolitan Catchment Management Authority, is expected to remove approximately 2,353 kg of sediment & 13kg of nitrogen annually before it enters Wolli Creek, which flows into the Cooks River & on to Botany Bay.   Their sign says that the system is designed to remove 100% of gross pollutants, 79% total suspended solids, 57% total phosphorus & 30% total nitrogen.  It’s beautiful & a terrific boon for the environment.  It’s also well worth a visit.

I made a short video of the Johnston Street Bioretention Basin & Illoura Reserve here –

Showing the swale & the path to Illoura Reserve which is just around the bend.

Today, 22nd March is World Water Day. The UN says the objective of World Water Day 2011 is to “focus international attention on the impact of rapid urban population growth, industrialization & uncertainties caused by climate change, conflicts & natural disasters on urban water systems.”

The theme for 2011 is Water for Cities & “aims to spotlight & encourage governments, organizations, communities & individuals to actively engage in addressing the challenges of urban water management.”

During last Sunday 20th to Monday 21st March parts of Sydney received a record-breaking 6 weeks of rain in just 24 hours with the weather forecasters saying this was related to climate change.  The UN says climate change will force more people to live in cities, further stressing the current water management infrastructure.

Stormwater entering the Cooks River at Mackey Park. This is a slow trickle compared to many other occasions

You only needed to be out on the roads last Sunday to see that many parts of Marrickville LGA were flooded & driving conditions were dangerous.  Most stormwater in Marrickville LGA enters the drains until eventually reaching the Cooks River.  It’s great Marrickville Council has built a number of bio-swales near the river & set up pollution traps to filter the stormwater as it enters the river. The swales clean up the oils & other ground pollutants collected by stormwater. However, swales are relatively new infrastructure & there is much more work to be done across all the relevant Councils before we can say that the Cooks River is fully protected from stormwater pollutants.

Cooks River pollution trap at Mackey Park

Sydney City Council is planning to capture stormwater from roofs of a large residential area in their Sustainable Street Project.  Thousands of litres of stormwater is already being collected in Myrtle Street Chippendale proving that it can be done easily & cheaply. This water is used to water their verge gardens & so far there has not been a need to use water from a private home.

To divert & collect water from roofs is not rocket science so I wonder why we are not all doing it in cities & town across Australia.  Marrickville Council has said that many of the new street trees planted die due to lack of water. Very few people want to water the street tree out front because of the added cost to their water bills, yet rainwater from our roofs can be easily diverted to the street tree & verge. Instead, most of the stormwater races past over hard surfaces & the tree gets only as much water as it can grab.  If it is a tree in an area that floods, it gets a bigger drink. If not, then it has to learn to survive on very little water or send its roots to where it can access water, often the front garden of the nearest property. This creates problems with some properties & yet it need not happen.

Cooks River pollution trap near Steele Park

The UN says the following about urban water – “There is growing evidence that water resources will be significantly affected by climate change, both in quantity & quality, particularly through the impact of floods, droughts, or extreme events. The effect of climate change will also mean more complex operations, disrupted services & increased cost for water & wastewater services. In addition, climate change & disasters will result in bigger migration to urban areas, increasing the demands on urban systems.”

Pretty serious stuff, especially for poorer communities in the third world. If climate change does happen in the way scientists expect, then water will become a major issue for us as well & we won’t be happy to see run across our streets, down stormwater drains & into rivers or oceans.  Water will be far too precious a commodity for us to allow this to happen.

Farmers in NSW, Victoria & South Australia who rely on water from the Murray-Darling River system have already experienced the environmental destruction, loss of diversity & extreme difficulty growing food while having to buy & get water delivered from elsewhere.  I predict that it won’t be too many years before many of us will choose to capture rainwater for our own use because the price of turning on the tap will be prohibitive & Councils will have to address our dying water management infrastructure, again because of costs.

We are the lucky ones with numerous taps inside & outside our homes with hot & cold running clean water.  Here are some unnerving stats to finish with –

  • Every second the world’s population grows by 2 people.
  • 493 million people share their sanitation facilities.  This means something like 1 toilet for a street or neighbourhood, not 1 toilet for a household.
  • 1.4 billion people do not have access to clean drinking water.
  • Every 8 seconds a child dies from drinking dirty water.
  • The World Health Organisation says 80% of all sickness & disease worldwide is related to contaminated water.

You can read about World Water Day here –

I have written about a way to capture rainwater from your roof to water the verge & street trees here –

A few decades ago the water of the Cooks River was safe to drink & swim in. A few Councils along the river & many community volunteers are working to restore the river for the benefit of future generations & urban wildlife. The names & contacts of local volunteer groups are in the blogroll on the left-hand side



1.      In a shocking case of environmental vandalism, the Los Angeles County Department of Public Works chopped down around 250 100-year-old Oak & Sycamore trees across an 11-acre site called the Santa Anita Wash Oak Grove. The trees were razed so they can dump 500,000 cubic yards of silt that they intend to dredge from a nearby reservoir.  The community vehemently opposed the destruction of the Santa Anita Wash Oak Grove, but the destruction went ahead as planned & this in a state that prides itself on it’s climate change initiatives. I would have thought that the silt could have been transported to another place to be used rather than destroy a 100-year plus habitat.  To see the Santa Anita Wash Oak Grove for yourself, here is a 3.42min YouTube video –!   & article –,0,3043421.story

2.       We have always known it & now Australian research by Professor Burchett of the University of Technology Sydney has proven it …. pot plants relieve workplace stress. “We found that plants had a very strong wellbeing effect. It was a reduction of a whole lot of negative feelings: anxiety, anger, depression, confusion, fatigue & stress.” Trees are just bigger plants & have much the same benefits.

3.      In a bold move by the Natural History Museum of Los Angeles, 3.5 acres of carpark will be torn up to create an urban wilderness experience & exhibit.  What they intend to create by July 2011 is fabulous.  I hope this approach becomes commonplace.

4.      Glenn Ridge in New Jersey US has established a new Shade Tree Commission that will oversee the health & well-being of publicly-owned shade trees.  I have not heard of this type of body before. The Shade Tree Commission will ensue that the care of public trees is open & transparent & will work with the community via outreach & public forums.

5.      Polycyclic aromatic hydrocarbons  (PAH) are in coal tar which is used to seal roads & carparks. Heavy pollution of US streams, ponds & lakes has been tracked to the use of PAH.  Everything we use ends up in our riverways or oceans eventually.  It’s time we stopped opting for the quick solution & chose more natural non-polluting products. They are available.

6.      Research by scientists at the National Centre for Atmospheric Research found that deciduous trees absorb about 1/3 more of oxygenated volatile organic compounds & at a faster rate than expected, up to 4 times faster. Oxygenated volatile organic compounds are particularly bad for human health.  This is why as many trees as possible need to be planted along our main roads & thoroughfares.

7.      Scientists from the Swiss Federal Research Institute for Forest, Snow & Landscape in Zurich published research that examined “nearly 9,000 pieces of wood, mostly collected over the past 30 years by archaeologists who use tree rings to establish the age of ancient sites or structures, a technique known as dendrochronology. The result was a continuous – & precisely dated – record of weather in France & Germany going back 2,500 years. The study also showed that climate & catastrophe often line up.”

8.      Green building legislation & initiatives are becoming commonplace in the US with 12 federal agencies & 33 states implementing them despite the recession. In 2008, 156 Councils nationwide had green legislation. By September 2010, 384 Councils have jumped on board.  I like this as Australia often follows the US.

9.      ExxonMobil, the world’s largest oil company says they expect CO2 emissions to rise

Trees are essential in managing global warming

by nearly 25% in the next 20 years, “in effect dismissing hopes that runaway climate change can be arrested & massive loss of life prevented.  According to the UK Met Office, if emissions rises can be stopped by 2020 & then be made to reduce by 1-2% a year, the planet could be expected to warm 2.1C to 3.7 C this century, with the rise continuing even higher after 2100.” The Australian Bureau of Metrology said that ocean temperatures around Australia have already warmed by 1.5 degrees. A warmer ocean means greater evaporation, which leads to higher rainfall.  This lesson came via ABC TV on the day of the great flood that hit Brisbane & SE Queensland this past week.  I think this is a very important article.

10.      Every year the city of Paris has 95 collection points across the city where its citizens can take their unwanted live Christmas tree which are mulched to be used in the city’s parks & gardens. From 15,000 trees recycled in 2007-2008, the number grew to 27,150 in 2009-2010.” Does Marrickville Council have a collection for Christmas trees? If not, it would be easy enough to copy this initiative wouldn’t it?

11.       Sudden tree death is killing the older trees in the UK.Already 4 million trees have been felled or marked for destruction.” This is a tragedy.

12.       Friends of the Trees, a volunteer group in Portand have just finished planting their 400,000 tree since the group started 21-years ago. My deepest respect goes to them.

13.      In other good news, the Philippines have used Tree Surgeons to successfully heal sick

IKEA Fig January 2011 - doing well

trees. The emphasis is mine.  Researchers claimed 24 narra trees aged 68 to 73years old were treated after they were on the verge of dying considering that they were described to be landmarks when the construction of the Binga power plant & other facilities commenced in the early 1960s.  Seven trees had major treatments using steel bars as mechanical support during the tree surgery while the seventeen others underwent semi-major surgery.  Experts claimed tree surgery is the practice of repairing sick & damaged trees to subsequently restore its physical appearance. It is done by removing the injured or deceased parts & treating the same with antiseptics & healing aids & filling the cavities with special materials & cement to fix the surface.” Why does this not happen any more? Or if it does, why do we not hear about it?  I know some specialist Arborists look after veteran trees or move trees & care for them like the IKEA Fig, but this kind of work used to be done routinely on suburban trees. Now it seems like if a limb is sick, the whole tree has to come down.

Fantastic Fig tree in Marrickville Golf Course

Birds on Fatima Island in the Cooks River

I downloaded the report because there was interest in the issue. The first thing that struck me was the cover page. It is a photo of the banks of the Cooks River probably taken early last century, but that’s just a guess.  The environment looks unbelievably bad, not what I expected at all. I had a vision of a pristine river with natural banks & trees everywhere. Instead there is a very large denuded area about the size of Steele Park with 4 tall trees, 1 dead & another on its way out.  There are around 16 newly planted saplings in the photograph with what appears to be a team of men doing some work chopping away sandstone from an area about 20 metres from the bank. The bank itself is ‘natural’ with not a mangrove to be seen. Pity copyright prevents me from including the photo.

This photo shows that Marrickville Council have done enormous restoration & re-vegetation work on the Cooks River, its bank & the public space alongside the riverbank which I guess was precisely what they intended.

On to the report itself – First up is an aspiration of what the future could be like (words in bold are my emphasis) –

“In 2050….. Our people-friendly streets & roads are clean & there are minimal hard surfaces. Streetscapes, roads & roofs are ecosystems, available for local food production. Stormwater treatment systems are also habitat for frogs, insects and bandicoots. Transport is now completely green, there are few cars & people mostly walk & cycle.  Our community revolves around shared green spaces that are self-sufficient with water. Parks have wetlands & forest reservations. We swim in Dibble Avenue Waterhole & the Cooks River waterways that are also habitat for wildlife. The Cooks River & its foreshores are clean, in a natural state & can be used for recreation & fishing.”

Now wouldn’t that be amazing & something wonderful to pass on to future generations.

Marrickville Council has so far created 3 Subcatchment Management Plans: Illawarra Road Subcatchment Marrickville South, Tennyson Street Subcatchment Dulwich Hill & now Riverside Crescent Subcatchment in Marrickville South.  There are 21 subcatchment areas in Marrickville LGA, so it’s big job.

I found the Riverside Crescent Subcatchment Management Plan exciting for a number of reasons.

  • The goals are big, but achievable.
  • Council intends to work with the community.
  • Private property issues with stormwater & the creation of permeable surfaces are also to be addressed.
  • Council expects measurable improvement by 2019.

Cooks River

Approximately 60% of the Riverside Catchment is impervious surface. Of that 60%, roads make up 34% with roofs, driveways & carparks making up the remaining 66%.

From the Report – “The implemention of the Riverside Crescent Subcatchment Management Plan can only happen if citizens make practical changes on their properties. (my emphasis)

The idea of “depaving” is gathering momentum in the USA, especially in Portland, Chicago & Berkeley. With the permission of a landowner, paved areas are removed & replaced with vegetated areas. In Portland, a community organisation called has led depaving projects in private backyards, school yards & parking lots.” (Portland has done some incredibly innovative & dynamic things regarding street trees, verges, kerbs & the community is heavily involved. I would love to visit & see for myself.)

As with ‘green laneways,’ the only way to stop up to 85% of rainwater becoming stormwater & ending up in our drains & then eventually into the small creeks in the LGA, the Cooks River or the ocean is by removing as many of the impermeable surfaces as we can. Making surfaces permeable

A section of fantastic restoration work on the bank of the Cooks River at Ewen Park

allows water to go where it should, into the ground or into rainwater storage tanks for use in & around the home. Once rainwater enters the ground, it fills the groundwater & travels through the natural causeways through the ground to reach creeks, the ocean or the Cooks River. The water is by then, cleaned of pollutants. Council isn’t kidding when they say they are going to need to co-operation of the community.

Last week the Australian New Zealand Climate Forum released figures showing that Sydney is already 0.65C hotter than Newcastle. This may not seem like much, but a global temperature rise of just 2 degrees is thought to be catastrophic & result in major problems with food production, water, rising sea levels, 30% animal & plant extinction, weather patterns, floods, drought, & unsustainable living conditions for people.

The heat island effect is causing the heat stored in our many hard surfaces to remain during the night & this makes for one very hot Sydney.  We have already noticed significant changes over the last 3-4 years & unless we do something about this soon, Sydney is only going to get hotter.

Stamped cement driveways will be a thing of the past because we will eventually choose to not live with the heat stored on our property.  Hopefully Council’s Subcatchment Plan will enthuse people to remove theirs & install a permeable driveway instead. If Marrickville Council are successful in encouraging community co-operation & participation, there will be huge changes in the way the community views the environment in terms of water, trees, verges, litter & dumping.

Dibble Avenue Waterhole - this has the potential to be amazing

Dibble Avenue Waterhole is also targeted in the Plan. According to Council’s Report, the historic & potentially very beautiful Waterhole that is fed from direct rainfall, groundwater & stormwater runoff from adjacent properties has “high concentrations of heavy metals including arsenic, cadmium, copper, mercury, nickel, lead & zinc. These exceed guidelines’ values & pose an ecological risk.   ….up to 25 species of birds including several important migratory & wetland birds, such as the Eastern Curlew. Chestnut Teals, Dusky Moorhens & Australian White Ibis, have been observed most recently. Long finned eels, dwarf flathead gudgeon & mosquito fish have also been recorded.”

I am really happy that Council is doing this kind of work, because not only will it improve our environment in terms of general cleanliness & a cleaner river that we may one day be able to swim in, it will also increase biodiversity by offering homes & food for urban wildlife.  It will also be tackling global warming & the lessening the impact of climate change.  Okay, it’s a small scale, but hopefully all the Councils in Sydney & across Australia will do the same or similar & this process is repeated across the world.  We have to clean up our own back yard.

One very small thing we can do right now is stop buying bottled water or stop throwing plastic bottles away as litter. In all my walks along the Cooks River, the most common litter I see in the river, along the banks & in stormwater catchment drains are plastic water bottles. Some of them can travel to the Cooks River through the stormwater drains from as far as Newtown. Just making a change here will lessen the pollution load in the Cooks River.  It’s Marrickvlle LGA’s little piece of paradise & it can be so much better.

There is much more in the Riverside Crescent Subcatchment Management Plan. For those of you who are interested, it can be downloaded here (6.5MB) –

Cooks River with Tempe railway bridge & the bridge at the Princes Highway in the distance





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