Protecting Water Quality in Zorinsky Lake

In the late 1990s, the City of Omaha knew there was excess sediment entering into Zorinsky Lake, a city-managed reservoir. The 255-acre lake is one of Omaha’s premier recreational lakes while also providing essential flood control measures. Twenty years later, the Papio-Missouri River Natural Resources District constructed three water quality basins to protect Zorinsky Lake from sediment, silt, pollutants and nutrients. The Zorinsky Basin 2 Dam works in conjunction with three other water quality basins located upstream of Zorinsky Lake. 

Uniquely, as construction progressed into 2019, and the surrounding residential developments grew, adjacent landowners opposed the on-site mitigation measures. The team quickly modified the stream mitigation strategy during construction. They moved the stream mitigation to Flanagan Lake, which saved significant costs for P-MRNRD. It also provided an opportunity to increase the stream’s ecological function by constructing rock riprap vanes strategically located along and within the stream channel.

The new basin increases property values, minimizes reservoir maintenance at Zorinsky Lake, improves aesthetics, increases habitats, improves the aquifer and converts the area from a degraded, disconnected stream habitat to a lake habitat.

The project team overcame significant challenges with the project, including:

• Tremendous growth within the area as construction progressed
• Mitigating high groundwater levels during excavation of the drawdown outlet and chute spillway turndown
• Combating a wet construction season with above normal rainfall
• Mitigating poor subsurface conditions by sequencing the construction of the embankment to allow for settlement

From the project's onset, our team worked intensively with P-MRNRD and project stakeholders to deliver the project. Throughout planning, design and construction, the team minimized environmental impacts, reduced construction costs and worked collaboratively with the stakeholders.

Completed on schedule and on budget, Zorinsky Basin 2 Dam was created by taking a big-picture approach to water quality to benefit the community for generations to come.