Introduction

Waukesha is a sprawling suburb of Milwaukee, Wisconsin. Serious groundwater contamination issues have created a scarcity of drinking water for Waukesha, forcing the city to look towards other sources. After yearslong negotiations with state authorities, Waukesha received approval in 2016 to divert drinking water from Lake Michigan and begin a $300 million pipeline project with a return flow requirement as part of the Great Lakes Compact. Waukesha became the first community outside of the Great Lakes Basin to gain access to this water source. This has raised concerns in the water community, mainly over how this approval could set a precedent for the Great Lakes to become a water subsidy for urban sprawl outside of the basin, effectively encouraging water diversion methods that are not sustainable.

While the chosen pipeline alternative is costly and inefficient, our proposal works within these constraints given that the project has already been approved and is currently under construction. Because of conflicts with impacted neighboring communities along with delays due to the COVID-19 crisis, this project will not be completed by the initially expected deadline of 2023. This has presented us with the unique opportunity and timeframe to propose a water solution that makes this system more sustainable and adaptable to future conditions.

The proposed water solution is a multi-benefit approach that incorporates a water reuse and dual distribution system at Waukesha’s Wastewater Treatment Center (also known as the Clean Water Plant) and a constructed wetland at the pipeline’s outfall into Root River. Below is a flow chart of the planned return flow system, accompanied by our proposed additions.

Part I: Water Reuse and Recycling

The first part of the proposed solution is the addition of a dual distribution system that supplies water for the surrounding industrial and manufacturing plants. Existing industrial facilities near the Clean Water Plant, which include a metals processing facility and a gas supplier, can utilize recycled water for operations and help the city conserve more water. This water supply is treated to a lesser quality that is appropriate for industrial uses. After use, the industrial plants return water to the Clean Water Plant to be treated and then released into the pipeline. This water recycling approach for existing manufacturers in close proximity to the Plant removes the issue of high costs that result from extending pipelines that can cover otherwise large distances for different uses i.e. agriculture, households, golf courses, etc.

In addition to water conservation, this water reuse addition can incentivize and allow for industry growth in Waukesha where the economy is largely made up of manufacturing. While Waukesha had requested 10 million gallons per day of diverted water from Lake Michigan, the Great Lakes Compact only allows for retrieval of 8.2 million gallons per day (mgd). Subsequently, one of the city’s concerns was that the diverted water supply would be insufficient in promoting industry growth. However, adopting a water reuse approach can address this gap in water supply and accommodate expansion in manufacturing.

Part II: Constructed Wetland

The second part of our proposed solution creates a constructed wetland at the confluence of the return flow pipeline and the Root River. The proposed project slated to begin construction earlier this year (prior to COVID-19) has caused a public outcry in Milwaukee among engaged citizens. Some fear that the 8.2 mgd return flow could damage the river and cause downstream flooding and there is also some concern that the treated wastewater would dirty the river. An extensive study was performed on this process prior to the pipeline’s approval showing that the treated wastewater would actually create higher quality water in the river (by diluting the already polluted waterway) and that the additional water would be inconsequential to flooding. Regardless, we believe that a constructed wetland would help alleviate the public’s concerns and create many auxiliary benefits.

The Root River has a peak discharge of ~5,000 cubic feet per second and although the 8.2 mgd added by the pipeline makes an unnoticeable dent to the river’s peak flow, building a wetland at the confluence will add additional flood storage to the area and help mitigate potential impacts from climate change as precipitation events intensify and become more frequent in the future. The constructed wetland could also be made into a park where citizens would learn more about their local waterways and wastewater treatment, as part of school field trips and signage. A recurring theme throughout this semester is that most people are uneducated about how their local water system operates this constructed wetland could help fill that void. For example, the public’s concern about treated wastewater returning to the Root River is moot considering 93% of Wisconsin’s treated wastewater is already returned to rivers.

Constructed Wetlands are not a new technology. The idea behind them is quite simple, let wetlands, whose ecosystem service creates better water quality, clean any of the remaining effluents. A classic example of a constructed wetland is the 93-acre Green Cay Nature Center in South Florida where the constructed wetland serves as a popular outdoor attraction in the crowded suburb. As Milwaukee suburbs continue to grow our 105-acre proposed project at the suburban rural edge would likely be a welcomed addition.

The constructed wetlands will increase aquifer recharge, serve as additional habitat for wildlife, and may even mitigate any unprecedented flooding. If the constructed wetland were to become popular it may influence future wastewater treatment plants in the region to create similar projects rather than relying on just chemicals and machinery. Our proposed wetland has a basis in the history of Great Lakes diversions as well. The Great Lakes Charter which oversaw large diversions from the lakes before becoming the Great Lakes Compact in 1986 required conservation of the local environment to offset the loss of diversion. With little fixed pricing on ecosystem services and the conversion of water and preservation this part of the charter fell through. However, as the Waukesha diversion is the largest diversion outside of the basin in modern history we felt it was important to continue this tradition of investing in the environment and continuing to push Waukesha’s role as having some of the most innovative water conservation measures in place should another eligible county require similar diversion in the future.

Conclusion

From our research and through this class we learned that water problems are multidimensional and can happen anywhere. Even in Waukesha where bubbling surface springs were once rumored as an elixir and needed to be protected from diversion. It is therefore imperative that in the age of climate change all municipalities even ones with abundant water supply incorporate Integrated Water Resource Management to best conserve their freshwater sources.

Despite Waukesha having some of the most innovative conservation measures in the state, we felt that it was important to continue to push even further. In doing so, the town can continue to grow its industry. With the Great Lakes Compact only approving 8.2 of the county’s originally requested 10.1 mgd the county feared that growth and industry would be stymied, however, with the implementation of a dual distribution system, industry can continue to grow around the water treatment plant in an area with vacant lots and industrial zoning. By restructuring the return flow, we believe that Waukesha continues to push the boundaries of good water conservation practices, and the county serves as a cautionary tale of believing water is expendable and as a role model for all municipalities across the country showing what is possible with better water management practices.