Lake Michigan provides a large portion of the potable water for Chicago/Cook County and the five collar-county regions. [Credit: istockphoto.com ianmcdonnell] |
Use of reverse osmosis (RO) or nanofiltration (NF) membrane technology may enable communities to desalinate impacted groundwater, but the technology is costly. Communities have sought new water sources by banding together to form water districts, allowing a larger financial base to pursue better source water.
Finding Long-Term Solutions
The issues associated with identifying effective long-term solutions are unique to every community. Solutions undoubtedly will include conservation, diversification, and engineered solutions.
Conservation efforts, including public education and usage restrictions, have yielded success in a number of Chicago suburb communities, where per capita water consumption has decreased by as much as 15-20%. The communities that utilize Lake Michigan water are required to reduce unaccounted water to no more than 8%.
Many communities are adjusting their water rate structures to help ensure a sustainable supply to meet the demands associated with projected growth.
Communities are also diversifying their water "portfolios." For example, suburbs south of Chicago have tended to draw from Lake Michigan; southwestern suburbs are tapping a combination of lake water and deep-well water; western suburbs use a combination of shallow wells and deep wells; and far-western suburbs are mainly tapping shallow sand and gravel aquifers.
Considering the Alternatives
As a community seeks a long-term solution, it must consider the safety and sustainability of its current source or sources, identify alternatives, and compare the lifecycle costs of each alternative. In the late 1980s, the community of Aurora, Illinois, retained Crawford, Murphy & Tilly (CMT) Inc. to evaluate alternatives. Based on an engineering and lifecycle analysis, CMT recommended use of a combination of three water sources – deep and shallow aquifer wells, the Fox River – and construction of a treatment plant that uses lime to soften the finished water. This solution provided redundancy and high-quality treated water. Recently, the city constructed additional deep and shallow wells to help balance the volume of water from the various sources and provide sufficient source water should the Fox River water be temporarily unavailable.