Agricultural drainage wells (ADWs) were developed in the early to mid 1900’s and discharge cropland tile drainage water to underground aquifers. However, testing for pollutants in the 1980s revealed that these wells also carried bacteria, nitrates, and in some cases, household septic drainage straight to drinking water aquifers and the groundwater supply.
The fund was established in 1997 to protect drinking water aquifers by cost-sharing with landowners to close agricultural drainage wells and develop alternative drainage outlets to surface streams or install alternative management practices.
Projects are typically constructed through drainage districts, although some projects are undertaken by individual landowners. Some of the remaining wells to be closed are located in karst areas with shallow limestone.
- 300 registered agricultural drainage wells (ADWs) in Iowa
- 100 ADWs closed by landowners, Watershed Improvement Review Board funding, or determined by the Department of Natural Resources (DNR) to not be ADWs or to be non-functioning
- 170 ADWs closed to date using $15.66 million of assistance funds
- 5 ADW closures in project construction phase
- 9 ADW closures in design phase with 2018 construction
- 16 ADWs remain in continued use with DNR permits.
- 6 ADW closures anticipated for FY19
The Iowa Agricultural Drainage Well Research and Demonstration Project was established by the Iowa Groundwater Protection Act. That legislation charged the Department to conduct a research and demonstration project to address concerns about contamination of groundwater through use of agricultural drainage wells (ADWs).
All registered ADWs in Iowa have now been studied to characterize the costs of ADW closure and development of alternative outlets to surface watercourses. The studies were performed by drainage engineering firms under contract with the Division.
Through these studies, preliminary engineering concept designs have now been developed for alternative outlets for all of the registered ADWs. The details for each closure project vary and depend on what the engineers design. These studies and preliminary concept designs are now being used by the Division and involved ADW owners in the Agricultural Drainage Well Closure Assistance Program.
Research to develop improved in-field management of fertilizers and herbicides for areas draining to ADWs has been conducted by Iowa State University under contract with the Division. A research installation was developed for this project in Pocahontas County, consisting of 78 research plots, two-cell wetland complex, and a controlled-drainage cropping area. The research plots are equipped with individual tile drains from which continuous flow-composited water samples are collected 24 hours/day throughout the growing season by automated sampling equipment.
The Agricultural Drainage Well Research and Education effort, while conducted to address the concerns about ADWs, has statewide application in dealing with the water quality concerns about nitrogen and herbicide movement from cropped lands to Iowa’s streams and lakes. Research and outreach efforts are continuing to develop and implement new strategies to address these environmental concerns.