Restoration of Three Mile Lake
Background
HEI began work on the Three Mile Lake Restoration project in September of 2020, working with the Iowa Department of Natural Resources (DNR) officials to develop engineering design plans for watershed best management practices (BMPs) to retain sediment and nutrients as well as provide in-lake improvements to enhance water quality. Three Mile Lake is a large, state-owned reservoir in southern Iowa that is a major recreational resource and drinking water supply for the City of Creston and the Southern Iowa Rural Water Association.
The Project
HEI performed field/topographic survey, design, permitting, wetland and stream mitigation, and construction phase support. The project includes four watershed impoundments, stream mitigation, three new in-lake forebays, and the rehabilitation of the existing sediment forebay, which is largely silted in and no longer trapping new sediment from entering the main lake. Additionally, shoreline stabilization and in-lake habitat structures were included to improve the lake’s water quality and fishery. Construction was performed in two phases and the project was complete in January of 2025. The lake is intended to refill for full recreation and water supply.
- The project included the design of watershed BMPs, development of quantities/costs, and quantification of sediment and phosphorus reductions.
- A creative design and permitting approach developed new alternatives that significantly reduced construction costs for the restoration of the existing silt dike.
- Detailed environmental assessments, extensive USACE coordination during permitting, and mitigation planning.
Project Details
Client: Iowa Department of Natural Resources
Location: Union County, IA
Project Highlights
- The project included the design of watershed BMPs, development of quantities/costs, and quantification of sediment and phosphorus reductions.
- A creative design and permitting approach developed new alternatives that significantly reduced construction costs for the restoration of the existing silt dike.
- Detailed environmental assessments, extensive USACE coordination during permitting, and mitigation planning.
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