Upper Couderay River Watershed Agricultural Erosion Vulnerability Assessment

Project Abstract

This project analyzes the potential vulnerability of agricultural lands to soil erosion in the Upper Couderay River Watershed.  Soil erosion from agricultural lands produces a source of phosphorous to Lake Lac Courte Oreilles (LCO).  An Erosion Vulnerability Index is presented indicating agricultural parcels that are potentially vulnerable to soil erosion and would benefit from implementing agricultural best management practices.  The 125 square mile watershed contributes 12 billion gallons of water annually to LCO (LimnoTech, 2014).  Practically the entire watershed contributes water to LCO - from its own local basin and from three inlets fed from the basins of five other area lakes.  This characteristic of LCO makes it particularly susceptible to various water pollutants, including excessive nutrients.  

LCO harbors a unqiue and susceptible stratified two-story fishery.  The upper epilimnion story accommodates a self-sustaining musky and walleye fishery.  The lower thermocline story harbors cisco and whitefish, species that require cold, well-oxygenated water.  Cisco and whitefish are prey for walleye and musky.  The two-story fishery is at risk from excessive phosphorous and climate change that affect the temperature and availability of oxygen in the small thermocline story (Pratt, 2014).     

Measuring Erosion Vulnerability

Erosion vulnerability in the watershed is evaluated using the Erosion Vulnerability Assessment for Agricultural Lands (EVAAL) toolkit developed by the Wisconsin Department of Natural Resources (WDNR).  Erosion vulnerability is evaluated by analyzing factors of:  1) Elevation, 2) Precipitation, 3) Soil Erodibility (K-Factor), 4) Crop Management (C-Factor), and 5) Crop Rotations.  These factors are used to calculate: 1) Internally Draining Areas, 2) Runoff Curve, 3) Soil Loss Potential from Sheet and Rill Erosion (Universal Soil Loss Equation), and 4) Stream Power Index (Gully Erosion).  The Erosion Vulnerability Index is a combination of Soil Loss Potential and Stream Power Index.  The Erosion Vulnerability Index is then aggregated to the parcel level indicating which agricultural parcels are potentially most vulnerable to erosion and would benefit from implementing agricultural best management practices.

Principal Investigator 

Douglas Miskowiak

GIS Technician

Kyle McNair 

Grant Proposal

To view the Grant Proposal please click here.  

Final Project

To view the final project please click here.  

Project Maps

EVAAL Maps

Results

• Erosion Vulnerability Index by Parcel (See also Erosion Vulnerability Index by Parcel Table)
  
• Erosion Vulnerability Index by Parcel Table
• Erosion Vulnerability Index
  
• Stream Power Index - Gully Erosion
  
• Soil Loss Potential - Sheet and Rill Erosion
  

Inputs

• Elevation
  
• Precipitation
  
• Crop Rotation
  
• Internally Draining Areas
  
• Crop Management (C Factor)
  
• Soil Erodibility (K Factor)
  
• Runoff Curve Number
  

NM 590 Maps

• Fall Nutrient Spreading Restrictions for Concentrated Animal Feeding Operations
  
• Fall Nutrient Spreading Restrictions
  
• Winter Nutrient Spreading Restrictions
  
• Source Water Quality Management Areas
• Nutrient Management Parcel Index Table

Context Maps

• Bedrock Geology
  
• Presettlement Vegetation
  
• Outstanding and Exceptional Resource Waters
  
• Wetlands
  
• Impaired Waters

Presentations

Erosion Vulnerability Index:  Presented at the 17th Annual COLA Picnic - July 24, 2017