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 poor water quality?
Both external (watershed) and internal (lake) processes contribute phosphorus and sediment to Easter Lake decreasing water quality.
External sediment and nutrient sources (pollutant sources from the watershed)
- Runoff and pollutants from urbanized, developing, and agricultural land
- Stream bed and bank erosion
Internal sediment and nutrient sources (pollutant sources from within the lake)
- Internal lake phosphorus loading
- Shoreline erosion
- Lake bottom re-suspension
Internal pollutant loads result from the re-suspension of lake-bottom sediment, decay of dead organisms such as fish and aquatic plants, and from the shoreline. 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 lake bed vegetation. Easter Lake has also accumulated large amounts of sediment at the lake bottom over time. This increases the ability for phosphorus to mix into the water column.
Sediment & Nutrient Reduction
Construction of an in-lake silt dike on the western arm (Yeader Creek branch) of the lake to reduce sediment and nutrient pollution to the main body of the lake and improve overall water clarity.
Silt dike, western arm Easter Lake 2018
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 Dredging and 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:
- Increased depth in shallow areas will reduce sediment re-suspension and increase water clarity
- Targeted dredging will improve 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) are currently being installed. To learn more about the fisheries renovation of Easter Lake, click here.
Lake Renovations Timeline
To learn more about each lake renovation milestone listed below click the links!
- Spillway improvements: Completed Winter 2015
- Sediment Basin Construction: Completed May 2016
- Hydraulic Dredging: Summer-Fall 2016
- Mechanical Lake Dredging: Summer 2017
- Stormwater Wetland Construction: Completed Summer 2017
- Mechanical Lake Dredging: 2018
- Shoreline Stabilization & Deepening: Completed December 2018
- Jetty Construction: Completed Fall 2018
- Fish habitat Installation: Completed Fall 2018
- Lake Refill: Filled as of March 2019
- Fish Restock: 2019-2020. The Iowa DNR plans to restock the lake with Largemouth Bass, Bluegill, Black Crappie, Walleye, and Channel Catfish.
- In-lake vegetation management: To manage vegetation visible above the waterline, Polk County Conservation staff will cut vegetation in June 2019. Remaining vegetation below the waterline will naturally decay over time.