Repairing Water Quality in 213-acre Recreational Lake
Lake Leba is a 213-acre recreational lake located along the Platte River near Fremont, NE, and has a mean depth of 13 ft and a maximum depth of 31 ft. The sand bottom lake was created by gravel mining operations in the 1960s and is groundwater-fed with minimal external phosphorus (P) inputs.
The Problem: High Phosphorus Levels Due to Nearby River
Initially, Lake Leba was pristine with periods of notable water clarity (>15 ft). In the 1980s, a dramatic decrease in water quality coincided with high P flood waters entering the lake from the nearby Platte River. By the early 90’s, P was over 150 μg/L, nuisance algal blooms persisted all summer, anoxic conditions in the lower two-thirds of the lake, and internal loading from the bottom sediments was the primary source of P.
Deploying Alum Vessels to Repair Water Quality
To balance phosphorus levels, government leaders in Nebraska decided to move forward with alum applications. Alum is a natural solution used to restore waterbodies with excess phosphorus levels. Its long-lasting results make it a popular water restoration tool in the lake management industry.
An 11-acre portion of the lake was isolated with two sand embankments to allow alum-treated vs untreated comparisons of water quality and plankton community structure. The isolated portion was dosed with 9,000 gallons of alum over three days. Samples were collected in the treated and untreated portions over the next 3 years.
The results were impressive…
Lake Leba Alum Application Results
The results of the alum application included the following changes:
- 97% reduction in internal phosphorus loading
- 74% reduction in water column phosphorus
- 65% reduction in chlorophyll (algae)
- 134% increase in water clarity
- 22% increase in oxic fish habitat
Want to know more about this project?
Click here for a detailed report of our restoration of Lake Leba.
