Construction of Williamsburg Wetland Completed

The Williamsburg Off-Channel Wetland project, located along the East Fork Little Miami River, ~12 miles upstream of Harsha Lake, was completed this summer by the dedicated partners listed below. The project began after the low-head dam was removed (2018) and a 3-acre drinking water reservoir was left behind in a 15-acre wooded floodplain. “When our watershed partners asked us to consider turning the reservoir into a wetland, we were excited to take another step forward to help local water conservation efforts,” said Mayor Mary Ann Lefker.

Clermont SWCD and the Clermont County OEQ worked with partners to assess the site. Recognizing the unique opportunity for a demonstration site upstream of a major lake, the partners and multiple funding sources allowed us to create an enhanced wetland design that provided habitat and water quality benefits, including the installation of high frequency water quality monitoring equipment.

To create as much water storage as possible, approximately 34,000 cubic yards of sediment was excavated from the floodplain and the reservoir. This improved the river-floodplain connection and allowed water to flow two ways through the system. An average rain event directs water into an inlet channel connected to the reservoir through an underdrain. Two wintering holes were dug along this path to provide habitat throughout the seasons. Within the reservoir, water meanders along a path to an outlet on the southern berm. The outlet pipe was sized and fitted with a flap gate to slowly release water into a meandering 2,000 foot floodplain channel nicknamed “the gut.”

During larger storm events, excess water can bypass the reservoir and flow directly onto the floodplain. The entire system was constructed with minimal slope to slow and store water, and remove pollutants before water re-enters the river. The water monitoring equipment tracks water flow and measures the amount of nutrients (nitrogen and phosphorus) and sediment removed from the river. The monitoring is a key component and partner agencies will study the data to understand how constructed wetland systems can help protect water resources, like Harsha Lake.

Special Thanks to all our Project Partners: Village of Williamsburg, U.S. Fish & Wildlife Service, the Duke Energy Foundation, Friends of Reservoirs/National Fish Habitat Partnership, Ohio EPA, U.S. EPA/ORD, Ohio State University and the Ohio Department of Natural Resources/H2Ohio Program.