Lake Mallalieu TMDL


Lake Mallalieu is a man made riverine lake located within the channel of the Willow River. Since 2004, Lake Mallalieu and an upstream reach of the Willow River have been included on the Environmental Protection Agency’s (EPA) 303(d) impaired waters list. The lake is designated as high priority for eutrophication and ph impairments due to excess phosphorus, while the upstream reach of the river is a low priority for dissolved oxygen impairments. The river’s designation is due to excess phosphorus and biological oxygen demand (BOD).

The Willow River has become degraded by excess nutrients, specifically phosphorus. Phosphorus is an essential nutrient required by all organisms. During 2008, the WDNR worked cooperatively with the St. Croix Watershed Research Station to develop a TMDL planning initiative in the Willow River Watershed. This plan is near completion. In order to achieve a 20% reduction of phosphorus to the St. Croix River, phosphorus reduction in the uplands is needed to meet the goal reduction.


St. Croix County Land and Water Conservation Department, in cooperation with WDNR and U.W. Extension would offer an approach to begin working with two agricultural producers in the watershed to reduce the amount of phosphorus leaving their agricultural lands. The baseline approach would be to establish the current known amount of phosphorus that is in the soil by taking soils test of the fields or using current soils tests from the landowners and determining the producers input and output phosphorus sources. Once known, staff can begin planning with the landowners to determine specific best management practices that can work with his/her operation while seeking to achieve our phosphorus reduction objective.


Farm planning Soil tests, Inputs/outputs P, RUSLE, Snap +, Landowner developed NMP with staff assistance Farm visit - onsite, Determine BMP's to be implemented Soil tests: 600 acres/1 sample per/5 ac. 120 samples @ $7.00 = $840.00 Staff planning/onsite, etc. 200 hrs per farm @ 40.80 hr. = $16,320

QA Measures

Run Project Summary Report

TMDL/303d Projects
TMDL Development
Lake Mallalieu TMDL
Reports and Documents
TMDL Implementation Plan
Condition Assessment Report
The purpose of this work is to monitor the fall population length frequency and catch per unit effort of sunfishes, yellow perch and crappies in parts of Navigation Pool 7 of the upper Mississippi River. A secondary purpose is to estimate length and size distributions of other game fishes caught
Activities & Recommendations
TMDL Implementatoin
Lake Mallalieu TMDL Implementation