Hickory Grove Lake Restoration

Background

Hickory Grove Lake is a 100-acre constructed lake in Story County, Iowa, with a lake to watershed ratio of 40:1. In recent years, the lake has experienced a number of rain event-driven water quality problems that are negatively affecting this resource. Sedimentation in arms of the lake has impacted recreation and surface run-off has led to gully erosion, debris, and nitrogen spikes in samples collected from the watershed.  Additionally, the beach at the lake has been listed as impaired due to high concentrations of indicator bacteria. While the fishery remains relatively healthy, carp have limited vegetation in the lake.  Aquatic vegetation is important fish habitat and helps keep water clear by removing nutrients from the water column and minimizing sediment re-suspension due to wind and wave action in nearshore areas.

Starting in 2008, a watershed technical advisory team was formed to discuss water quality improvement efforts at the lake. The NRCS received a development grant in 2008 to determine critical areas within the watershed for restoration and complete a land use assessment. In 2011, Iowa State University also received a planning grant to develop a watershed management plan for Hickory Grove Lake. This plan outlined strategies for managing bacteria levels at the beach and included recommendations for goose control, lake draw-down, sediment removal and a fishery renovation. View the Hickory Grove Lake Action Plan here (PDF). 

Watershed Improvements

SCC received a WIRB grant and partnered with DNR Lake Restoration to complete a livestock exclusion project and streambank stabilization project on the main tributary of the lake. The project was completed in 2016 and helped minimize new sediment and nutrients being delivered to the lake.

In summer 2016, DNR and SCC worked to complete a preliminary assessment of the park grounds to determine where additional practices could be placed to mitigate gully erosion in the park and improve existing sediment ponds in the park. Currently, DNR Engineering is designing elements of the project for completion in the 2017 construction season. Included in the project plan are BMPs to address critical gullies in the park, as well as improvements to the wetland located at the upper end of the lake.

Additionally, the County provided a cost-share program for watershed residents in need of updated septic systems. All unpermitted systems in the watershed have been improved to reduce nutrients delivered to the lake.

In-park Improvements

The overall goal of this restoration project is to improve water quality and recreational opportunities at the lake and remove the lake from the Impaired Waters List. Construction planned will include in-park watershed improvements to stabilize areas that are actively eroding within the park and rehabilitate existing sediment catch basins to prevent nutrient and sediment pollution from entering the lake. Planned in-lake restoration work includes the removal of excess sediment from arms of the lake, shoreline stabilization, fish habitat improvements, and updating the lake’s outlet infrastructure. Lake drawdown is slated to begin following Labor Day 2018 and the entire restoration will likely be completed in the next 2-4 years.

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