Little Lake Wissota TMDL

Purpose

Little Lake Wissota is a 400-acre eutrophic embayment of Lake Wissota, an impoundment of the Chippewa River near Chippewa Falls, Wisconsin (Hydrologic Unit Code 07050005, Wisconsin Waterbody Identification Code 2152800). The embayment has a maximum depth of 43 feet and a drainage area of approximately 67 square miles. Paint Creek is the primary source of surface water inflow to Little Lake Wissota. The Little Lake Wissota watershed is located in the North Central Hardwood Forest Ecoregion (Omernick and Gallant, 1988). This EPA Ecoregion is characterized by nearly level to rolling glacial till plains, significant agricultural land use and lakes with phosphorus concentrations greater than 50 ppb, indicative of eutrophic conditions. The lake was placed on the Wisconsin 303(d) impaired waters list in 1998 with a high priority ranking due to eutrophication and pH criteria exceedances. In addition, recreational uses are limited during the summer due to poor water quality from excess phosphorus (P) and sediment loading. Land cover in the watershed is primarily agricultural and forest. The goal of this TMDL is to reduce levels of phosphorus and sediment loading and decrease the extent and severity of summer algal blooms in Little Lake Wissota.

Objective

Little Lake Wissota is highly eutrophic with excessive concentrations of phosphorus and chlorophyll (a measure of algal densities) in its surface waters during the months of May through September (USACE 2004, Brakke 1997). Sediment and phosphorus from nonpoint sources of pollution enter the lake primarily from the Paint Creek watershed. Phosphorus is dissolved in the water or bound to sediment particles, and once in the system, this phosphorus becomes available to plants and algae. The lake’s relatively shallow depth, phosphorus-laden sediments and excessive water column phosphorus levels, contribute to significant algal blooms during the growing season (May - September). These eutrophic conditions impair recreational activities in the lake. In addition, algal blooms in Little Lake Wissota are accompanied by pH exceedances. The elevated lake pH levels are due to removal of carbon dioxide from water during photosynthesis (by macrophytes and algae). This reduction in carbon dioxide levels during daylight results in pH levels that frequently exceed the state criterion of 9.0. A reduction in sediment and phosphorus loads to the lake would result in a decrease in chlorophyll levels and reduction in maximum pH levels.

QA Measures

Run Project Summary Report

TMDL/303d Projects
Approved TMDL
Little Lake Wissota TMDL
2010
Active
 
Reports and Documents
42902710
The approval letter and decision document written by the EPA
Final TMDL Report
Final TMDL Report
Data Documentation Moon Bay and Little Lake Wissota Impaired Waters Listing Documentation, Chippewa County
 
Activities & Recommendations
TMDL Approved (USEPA)
Little Lake Wissota TMDL
TMDL Implementatoin
Little Lake Wissota TMDL
 
Waters