February 02, 2023

New partnership expands ‘Smart Wetlands’

Reducing nutrient loss

CHICAGO — The Wetlands Institute and Ducks Unlimited have combined resources to help Illinois farmers install Smart Wetlands.

Wetlands are one of the most effective natural water quality filters and are a major solution for reducing nutrient runoff and hypoxia. DU has teamed with the Illinois-based organization TWI to create new Smart Wetlands in strategic locations on agricultural fields.

Developed and tested by TWI on several working farms in Illinois, a Smart Wetland is a small, constructed wetland that uses naturally occurring processes to remove excess nutrients from agricultural tile drainage before it leaves cropland.

The constructed wetland is “smart” because it is specifically sited and designed to reduce nutrient loss via tile drainage, is a measurable practice in terms of directly monitoring nutrient removal because its nutrient removal effectiveness can be directly monitored, and is in alignment with Illinois’ systems approach to nutrient loss reduction.

In addition, a Smart Wetland is a resilient and relevant practice for a sustainable and productive farming operation that keeps working even as weather patterns change. It is a time-saving practice that can remove nutrients for 30-plus years with very little maintenance.

Key Components

The position, size and depth are the key components of a Smart Wetland. The best position for a Smart Wetland is within a waterway or adjacent to an existing ditch or stream to intercept and capture drain tile outflow.

Ideally, these locations are those small pieces of hard-to-farm or negative-revenue lands often found on a farm. The wetland can easily be designed to treat 30 to 200 acres of drained cropland.

The constructed wetland size is determined based on a ratio. The wetland treatment area should be 0.5% to 5% of the tile drainage area being captured. This ensures that the wetland’s capacity is large enough to remove nutrients effectively.

The ideal depth of water for a Smart Wetland is 12 to 18 inches. This shallow marsh ecosystem with emergent vegetation has the conditions needed to remove nitrates via a process called denitrification. While this depth is good for removing nutrients, it is not deep enough for fish.


Through the new partnership, TWI and DU will educate farmers on the benefits of installing Smart Wetlands and jointly pursue funding opportunities. TWI will share years of Smart Wetland modeling and technical know-how, and DU’s engineering teams will help design and implement new farm-based projects.

“Ducks Unlimited has conserved more than 15 million acres of wetlands across North America over the last 85 years, including more than 55,000 acres here in Illinois,” said Mike Sertle, DU biologist for Illinois.

“Most of our projects are on large stretches of land. What makes this partnership so exciting is that DU will help TWI expand the crucial practice of creating precision-sized marshes directly at the source of nutrient runoff.”

“Working with our ag-sector partners these last few years, TWI has learned how to make these wetlands work successfully within the context of productive row crop farms,” said Jill Kostel, TWI’s senior environmental engineer and Smart Wetlands project manager.

“Pairing our expertise with DU’s broad reach and strong farmer relationships creates exciting new opportunities to grow this conservation practice.”

Nutrient Loss Goals

Smart Wetlands can help Illinois meet its nutrient reduction goals of reducing its phosphorus load by 25% and its nitrate-nitrogen load by 15% by 2025. The eventual target is a 45% reduction in the loss of these nutrients to the Mississippi River.

The installation of Smart Wetlands will help combat the Gulf of Mexico’s hypoxia zone — a “dead zone” of oxygen-depleted water covering more than, 5,000 square miles at the Mississippi River Delta.

Hypoxia occurs after rain runoff carries phosphorus and nitrates into the Gulf from the Mississippi River. This dead zone threatens to deplete valuable fisheries and disrupt fragile ecosystems.

The Illinois River Watershed is one of the largest contributors to the Gulf’s dead zone. The same nitrogen and phosphorus runoff problem has caused recent hypoxic events in Midwestern waters, as well, including Lake Erie and the Ohio River.

Farmer Allies

Agriculture producers are the greatest ally for improving water quality. Michael Thacker, who farms 4,500 acres of corn and soybeans in Walnut, is an example of how landowners can blend profitable farming with conservation practices.

TWI installed a four-acre Smart Wetland and grassland-pollinator habitat on a parcel of Thacker’s farm. The project has successfully treated drain tile runoff from the surrounding 40 acres.

The University of Illinois at Chicago monitored the nutrient load before water entered and exited the constructed marsh.

Between 2016 and 2019, the small site removed more than 7,200 pounds of nitrates, or up to 46 pounds per acre of drainage area, per year.

“For all my life, this has been my home. I love what I have here. I have a daughter and I want to keep this area nice for her. The wetland requires no work on my part, and it makes me feel good that I’m doing things to help the environment,” said Thacker, also a DU member.

The partnership includes DU and TWI field staff spending time on the ground with prospective landowners, explaining the process and subscribing to farm bill programs and other grants to cover construction costs.

Tom Doran

Tom Doran

Field Editor