Where conservation meets production: The benefits of constructed wetlands

Every farmer knows the challenge of managing water and nutrients; constructed wetlands are a tool that can help protect yields and improve water quality simultaneously. Wetlands, as defined by the U.S. Environmental Protection Agency, are areas where water covers the soil or remains at or near the surface year-round or seasonally, including the growing period. These ecosystems take many forms and are shaped by their hydrology, water chemistry, soil type, and the vegetation they support. Among the various wetland types, constructed wetlands play an important role in agriculture and have become a recognized edge-of-field conservation practice.

Constructed wetlands are intentionally designed and built to serve a specific purpose, often mimicking the functions of natural wetlands. Unlike restored wetlands, which aim to bring back a wetland that once existed on the landscape, constructed wetlands are entirely new systems designed to treat tile-drained water. Within the Illinois Nutrient Loss Reduction Strategy, constructed wetlands are tracked as part of statewide conservation progress.

One of the most valuable services wetlands provide is the protection of local water quality. In agricultural settings, constructed wetlands are often sited at tile drainage outlets, where they can receive water from fields ranging from 30 to 200 acres. These wetlands act as natural filtration systems. While aquatic plants take up some nitrate, most nitrate removal occurs through microbial processes: bacteria in the wetland convert nitrate into nitrogen gas, a form that is released back into the atmosphere. According to Jill Kostel of The Wetlands Initiative, well-designed and appropriately sized constructed wetlands can remove at least 50% and up to 90% of nitrate-nitrogen from tile-drained water — making them one of the most effective edge-of-field practices.

If parts of your field flood year after year and hurt your bottom line, they might be good candidates for a wetland. Enrolling these acres in conservation easement programs, such as those offered by USDA-NRCS, can turn unproductive land into a long-term conservation asset. Other cost-share programs, offered through government and non-government organizations, are available to help offset installation costs. These programs enable landowners to install a constructed wetland economically while providing ongoing environmental benefits, including reduced nutrient levels and improved wildlife habitats.

Beyond water quality improvements, wetlands offer critical ecological value. They support a wide range of wildlife and pollinators, contributing to greater biodiversity across the landscape. When located in places accessible to the public, wetlands also create opportunities for recreation and outdoor enjoyment, allowing visitors to observe wildlife, engage in nature-based activities, and gain a deeper appreciation for wetland ecosystems.

Installing a constructed wetland requires careful planning and consideration. The practice may remove some land from production, and potential sites must meet specific technical criteria related to hydrology and soils. The initial establishment period can also take time as wetland vegetation becomes rooted and functional. Despite this, constructed wetlands generally require minimal maintenance once established. Farmers and landowners also note that pollinators and wildlife, such as monarch butterflies, often return to these areas surprisingly quickly, adding additional value to the landscape.

Interest in wetlands extends beyond agriculture. Some advocacy organizations in Illinois, such as the Sierra Club, view agricultural conservation practices like constructed wetlands as a practical opportunity for collaboration between agricultural producers and point-source facilities, including wastewater treatment plants. The Sierra Club’s Illinois Chapter considers constructed wetlands a cost-effective strategy for both farmers and municipal facilities working to meet nutrient reduction goals outlined in local Nutrient Assessment and Reduction Plans. By diverting and treating water through shared wetland systems, wastewater treatment plants can reduce costs, and farmers gain a conservation practice that enhances their land.

Looking for more details on how wetlands fit into your conservation plan? NLRS podcast episodes 69–72 cover a range of topics, including installation insights, easement programs, and farmer experiences. These episodes can be accessed at go.illinois.edu/NLRSPodcast.

Rachel Curry is a University of Illinois Extension agricultural and agribusiness educator and is part of Illinois Extension’s Nutrient Loss Reduction Strategy implementation team.