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Demonstration water tank

Mark Sabolch, the Water Management Engineer at Willoughby City Council, was guest speaker at the Progress Association’s AGM on 16 May 2004. He spoke about water in Castlecrag from both the perspective of an environmental water engineer, and that of a boy who grew up in the 1960s environment of Castlecrag.

Mark’s early childhood was in Castlecrag, his architect father having built the family home in The Bulwark. The house applied many of Walter Burley Griffin’s principles, with its flat roof and grey brick finish melding into the bush setting. The blocks on either side were vacant, so his early educational experiences were of the ‘enchanted bush’.

While Griffin’s achievements in relating the built to the natural environment are well known, the relationship of the fabric of Castlecrag to water is less appreciated. Griffin saw the importance of keeping the creeks as nature reserves to maintain the aesthetics of the bush and to ensure that the bays received clean water. The Castlecrag landscape design provides ‘zones of transition’ from the built to the natural environment.

As the built environment has become more dominant, native vegetation has been lost and the creeks and bays have become degraded, especially after storms. Mark presented photographs of recent examples of pollution from litter and scouring of creeks in Willoughby. Often sediment from building sites and other man-made interventions is deposited in the creeks and this kills off the biological life of the creek. He included extreme cases where chemical spills had caused major fish kills in our local creeks.

Willoughby Council is monitoring the environmental condition of the creeks by sampling the water and sediment, and measuring the presence of sensitive animal and insect species, such as the damsel fly. On the Signal Index of water quality, which uses a 1-7 scale with less than 4 being severely impaired, all the Middle Harbour creeks rate around 3.3. Against the AusRiverAS biotic index, the Willoughby creeks averaged around ‘D’ (impoverished). Thus, the creeks draining into Middle Harbour are in poor condition environmentally.

The key issue is, do people care? This is a difficult question to answer, but testing under the Streets to Creeks project suggests that residents are now more aware of where stormwater from their street goes. The results show, however, that residents regard problems associated with urban density and its impacts more highly than those of stormwater and water quality.

Mark spent some time outlining innovative stormwater management practices to reduce environmental impacts in future. These include vegetative drains in the median strip of roads, the use of roof gardens and greater use of rainwater tanks. A demonstration rainwater tank with plumbing for internal use and planter boxes that collect roof runoff have been installed at the community centre at Warner’s Park and there is optimism that innovative stormwater management practices will be applied to the LandCom development site at Willoughby Market Garden Park.