Lake Impairments Overview
Since its creation in 1967, Easter Lake has faced diminishing water quality due to high sediment and phosphorus loads originating in its predominantly urban watershed. Over the years, water quality has become poor in Easter Lake. The lake has shrunk from its original size in both surface area and volume. Sedimentation and nutrients have resulted in frequent algae blooms and low water clarity. Elevated bacteria levels in the lake have resulted in swimming advisories for Easter Lake. The lake also has some undesirable fish species (Common Carp and Gizzard Shad) and has a stunted panfish population.
What Is Causing Easter Lake's Poor Water Quality?
Both external (watershed) and internal (lake) processes contribute phosphorus and sediment to Easter Lake, decreasing its water quality. External sources include runoff and pollutants from urbanized, developing, and agricultural land along with stream bed and bank erosion. Sources of internal nutrient and sediment pollution from within the lake are contributed to internal lake phosphorus loading, decay of dead organisms such as fish and aquatic plants, shoreline erosion and sediment re-suspension. Sediment re-suspension occurs naturally in lakes due to wind and wave action, but can be increased due to other factors, such as bottom feeding fish (e.g., carp and bullhead) that feed on lakebed vegetation. By accumulating large amounts of sediment at the lake bottom over time, the ability for phosphorus to mix into the water column increases.
Red areas indicate historical siltation (areas filled with sediment) of Easter Lake.
In-lake Solutions To Improve Easter Lake's Water Quality
Sediment & Nutrient Reduction
The construction of an in-lake silt dike on the western arm (Yeader Creek branch) of the lake aids in the reduction of sediment and nutrient pollution to the main body of the lake and improves the overall water clarity.
Shoreline erosion in Easter Lake has contributed to the loss of surface acreage, depth, and habitat at Easter Lake. Shoreline erosion is a natural process that can be increased by physical factors such as wind/wave action, ice heave, recreational use, and lack of aquatic vegetation. To address shoreline erosion, key areas will be regraded and armored with a combination of riprap, Flexamat, and tall grass management and buffers
Targeted Lake Dredging & Sediment Removal
Since its creation in 1967 Easter Lake has lost 30% of its volume. To address sediment in Easter Lake, a targeted dredging approach will be used. Targeted dredging is a vital component of the overall restoration of Easter Lake and will enhance a number of other water quality improvements. Benefits of targeted dredging include increasing depth in shallow areas resulting in reduced sediment re-suspension and increased water clarity, as well as improving fish habitat, thereby increasing the water quality benefits obtained with the fisheries renovation.
The Iowa DNR, Polk CCB, and Central Iowa Anglers are working to enhance the fishery at Easter Lake. These exciting improvements include shoreline stabilization and deepening, removal of excess sediment, and construction of an in-lake silt pond. Additionally, a fish rearing pond was constructed near the lake to rear Walleye fingerlings. The spillway has also been updated to include a fish barrier to prevent undesirable fish (Common Carp & Gizzard Shad) from reentering the lake. Fish habit (cedar trees, spawning beds, catfish hides, and rock piles) have also been installed.