The Lake Illawarra Authority has expressed concerns over the long term impact of Sydney Water's $225 million plan to expand water and wastewater services into the West Dapto region.
Sydney Water's environmental assessment for the project was placed on exhibition in September, with information sessions held in the Illawarra during September and October.
The proposal includes the design, construction, operation and maintenance of 80 kilometres of new drinking water pipelines and 45 kilometres of new wastewater pipelines which will service the forecast 30,000 new homes and 500 hectares of non-residential development planned for the West Dapto area over the next four decades.
The issue of managing the increasing impact of developments in the Lake Illawarra catchment area has been high on the agenda of the authority in recent years.
In its submission the LIA said Sydney Water's environmental assessment does not demonstrate preservation of the lake's existing environmental qualities, "nor provide adequate commitment to potential mitigation measures" and the plan seeks approval of infrastructure that will increase the release of nutrients into Lake Illawarra.
"The LIA holds a strong view that it is appropriate to target a 'no net increase in nutrients' approach," the authority's submission states.
"The LIA notes that the current environmental protection licence for the sewerage system will permit increased release of nutrients and pollutants into Lake Illawarra.
"This is a cause for great concern. Consequently commitments ... to comply with the current EPL will not necessarily ensure the long term sustainability of the environment of Lake Illawarra."
Issues raised by the LIA were echoed in a submission from Shellharbour City Council which said the possible impact of nutrient increase as a result of overflow in Lake Illawarra was also "of great concern".
"The EA does not with any certainty or confidence ensure the ongoing health and viability of the lake," Shellharbour council's senior strategic planner Cheryl Lappin wrote. "This is relevant from a community recreational perspective as well as future commercial and tourism opportunities."