Northwater was retained to support the City of Springfield, Illinois, through its public utility, City Water Light & Power (CWLP) with emergency water supply planning and permitting. The City of Springfield is the capital city of Illinois; both its power and water supply rely entirely on Lake Springfield. Climate and streamflow modeling suggests that Springfield will experience serious water shortages during drought conditions. An emergency water strategy and plan was developed in order to source supplemental water in the event of a drought. Northwater assisted the city in the development and permitting of the emergency water supply plan by evaluating two options: 1) installation of a temporary impoundment on a nearby river and 2) a large supplemental water supply reservoir.
Temporary Impoundment: Northwater developed a monitoring and modeling strategy to address dissolved oxygen, phosphorus, and nickel loading during extreme drought conditions. It was determined that nickel and DO can be addressed with reasonable mitigation efforts, however, CWLP’s ability to meet phosphorus standards in such a situation would be cost prohibitive.
Supplemental Reservoir Construction: Permitting a new reservoir is challenging from a water quality perspective because the Illinois Environmental Protection Agency required that it meet the State’s phosphorus standard of 0.05 mg/L. Northwater was tasked with the Antidegradation Assessment component of the larger permitting effort. This included developing a reservoir and linked watershed model that incorporated strategic management practices needed to ensure the lake can meet the water quality standard under extreme drought conditions. Northwater designed and executed a rigorous 1-year water quality and streamflow monitoring program, a detailed watershed assessment and characterization, and a watershed nutrient loading model calibrated to instream data. The WASP model was selected to simulate reservoir conditions and Northwater’s custom watershed model was used to supply input loads to WASP and site and evaluate nutrient and sediment load reductions required through the strategic placement of management practices.
Northwater’s knowledge and experience with these efforts provided valuable insight into the best options to secure the water necessary to supply Springfield’s growing demands and ensure long-term drought resilience.
Read about the Lake Springfield Watershed Management Plan….
Lake Springfield Watershed Management Plan