Union Grove Lake Watershed Project

A USDA Cooperative Water Quality Project

Introduction
Farmers in the Union Grove Lake watershed made major changes in their farming practices to protect the lake's water quality. They increased profitability an average of $15.79 per acre annually while reducing potential runoff of nutrients and pesticides. Fine-tuning crop production and protection programs and implementing conservation practices reduced potential soil erosion by 31,325 tons annually compared to erosion rates before 1990. Recreational use of the lake has increased nearly 25 percent since 1989.

Union Grove Lake is a 118-acre lake located in Tama County. The 6,895-acre watershed is in both Marshall and Tama counties and is 85 percent cropland, primarily corn and soybeans. The lake, built in 1935, has long been a popular recreation site. Visitor numbers fell off more than 20 percent between 1980 and 1989 though because of declining water quality. Union Grove Lake's size and depth had decreased over the years and there was excessive growth of algae.

The 1983 "Union Grove Lake Diagnostic and Feasibility Study" carried out by Iowa State University (ISU) for the Iowa Department of Natural Resources (IDNR) found the major pollutants were sediment and crop nutrients from excessive erosion and field runoff in the watershed. Cost sharing assistance to producers for erosion and sediment control began in 1984 through the Iowa Department of Agriculture's (IDALS) Publicly Owned Lakes Program and the IDNR-administered U.S. Environmental Protection Agency's Clean Lakes Program.

Efforts expanded in 1990 when the Union Grove Lake Watershed Project was one of the first 37 Hydrologic Unit Area (HUA) projects selected for funding by the U.S. Department of Agriculture Water Quality Initiative. The cooperative project funds a Soil Conservation Service coordinator and an ISU Extension Integrated Crop Management (ICM) coordinator to provide one-on-one assistance to producers, who are also called cooperators. All 48 farmers in the watershed participate in this voluntary project, which will be completed by 1995.

The project's objectives are:

• assess pre-project practices for crop production and protection, sediment control, and livestock waste,
• implement an educational program on water quality protection,
• reduce sediment and livestock waste movement into the lake by developing and implementing conservation plans,
• develop educational programs on the economic and environmental benefits of sustainable crop and manure management, and
• use ICM to refine the use of crop inputs that are potential pollutants.

Additional support for the project is provided by the USDA Agricultural Stabilization and Conservation Service (ASCS), IDALS, and IDNR. An advisory committee that helps plan project activities is made up of cooperators, other producers, and local agribusiness persons.

Soil Erosion Declines
All farmers in the watershed completed implementation of their conservation plans by 1993, two years before the deadline set by the 1985 Farm Bill. This was a critical step to protect the lake because more than one-third of the watershed is classified as highly erodible_with potential soil erosion rates of five tons or more per acre per year. Some fields had up to 50 tons or more of soil erosion per acre per year before the project began.

For example, producers since 1990 have installed 100,000 feet of terraces, 160 acres of grassed waterways, 30 water and sediment control basins, and 80,000 feet of field borders. Project staff provided technical assistance for the use of special cost-share monies from the Publicly Owned Lakes and Clean Lakes programs.

Cooperators even exceeded federal standards to control erosion, making major investments in conservation practices to achieve these reductions.

Erosion potential is now 5 tons or less per acre per year on 100 percent of the watershed's tillable acres. Sediment movement into Union Grove Lake is reduced by 9,300 tons. Sheet and rill erosion fell from an average of 9 tons per acre per year in 1990 to 3 tons per acre per year in 1993 and gully erosion dropped from 4,500 to 160 tons annually in that time.

Soil erosion in the Union Grove Lake watershed also droppr d because producers leave more residue on fields, increasing from 33 percent in 1990 to 63 percent in 1993. Conservation plans document that no-till is used on an additional 3,500 acres in the watershed compared to 1990.

ICM
ICM is a systems approach to crop production and protection tailored to each producer's goals and resources. ICM seeks to maximize efficient use of inputs while maintaining or improving profitability. Two-thirds of the watershed's producers were introduced to ICM planning through the project and a complete ICM program is used on 45 percent (2,922 acres) of the watershed's cropland. ISU Crop Enterprise Records, which are part of an ICM program, help farmers determine profitability on a field-by-field basis.

Project staff worked one-on-one with cooperators and did intensive soil sampling by soil map unit to develop nutrient management plans for 12,080 acres farmed by cooperators.

Producers established field-by-field yield goals using a digital soil map database and their historic yield information. Sampling by soil map unit and realistic yield goals helped reduce fertilizer use on a number of fields, lowering both expenses and potential nutrient runoff. Producers in the Union Grove Lake watershed:

• reduced nitrogen rates an average of 29 pounds per acre per year_or 42 tons a year overall, and
• decreased phosphorus applications an average of 52.5 pounds per acre per year or more than 76.5 tons a year overall.

The project's ICM program includes weekly crop scouting, which provides valuable information the staff uses to make pest and field management recommendations. Producers then treat crops only when and where pest populations exceed economic threshold levels.

For example, one cooperator saved $ 1,200 on insecticide costs when ICM scouts determined that European corn borer numbers were lower than the economic threshold level. The producer was ready to treat because corn borers were a problem in neighboring fields. Another producer avoided spending $15 per acre in insecticide costs for 12 acres when scouts found evidence of cutting in only 10 acres of the 22acre corn field.

Financial incentives to move toward more sustainable nutrient and pest management programs, conservation tillage, and contour farming have been available to cooperators since 1992 through the ASCS Water Quality Incentive Project.

Implementation of Soil Conservation Practices in the Union Grove Lake Watershed

Crop land in the watershed treated to control erosion to 5 tons or less per acre per year.

Cooperative Extension Service, Iowa State University of Science and Technology, and the United States Department of Agriculture cooperating. Robert M. Anderson, Jr., director, Ames, Iowa. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.

This publication is funded, in part, by the USDA Extension Service contract 90- EHUA-1-0027 and the Model Farms Demonstration Project. It is supported by the State of Iowa, through the Iowa Department of Agriculture and Land Stewardship and the Iowa Department of Natural Resources with appropriations from the Iowa Groundwater Protection Fund and the Energy Conservation Fund.