Testing New Ways to Keep Nutrient Pollution Out of Green Bay

The Conservancy is working with partners to test new ways to reduce algae blooms in Green Bay by keeping soil and nutrients on the land and out of the water.

For Bruce Deadman, summer has always meant a cottage on Green Bay, fishing, swimming and messing around with friends. Now he’s there year-round, and he’s training his grandchildren in the fine art of messing around outdoors.

Some things have changed over the years, but one thing that has remained constant is the green algae that slicks the waters of Green Bay from July to Labor Day.

“When I was a kid, I remember going water skiing several times and plowing through totally green spray,” Deadman recalls. “And three years ago, my grandkids and their dog Brinkley came to visit on the Fourth of July. Brinkley jumped into the bay before we could stop him, but the kids couldn’t swim because of the algae bloom. The algae’s not as bad today, but it’s still there. We need to continue the efforts to reduce algae growth. It’s in everyone’s interest for the bay to continue to heal.”

For decades, the loss of phosphorus and other nutrients from urban and agricultural landscapes into rivers and streams during spring rain events and snowmelt has resulted in frequent algal blooms in the bay of Green Bay.

Too much phosphorus can stimulate excessive algae growth, which eventually sinks and decomposes in the water. The decomposition of the algae consumes nearly all the oxygen in the water, depleting the supply available to fish and other aquatic species and creating what is known as a Dead Zone.

We’ve all seen the photos— slimy, green water covering parts of the bay, large numbers of dead fish washed up onto the shore.

Lack of oxygen, or hypoxia, in Green Bay’s waters varies from year to year, but since at least the 1990s, the number of days each year with dead zones in the bay continues to rise.


To improve water quality in Green Bay, The Nature Conservancy is working with partners to test the ability of treatment wetlands and other restoration strategies to keep soil and nutrients on the land and out of the water.

The Conservancy is currently involved with two pilot projects to address phosphorus runoff into Green Bay:

Edge of Field Treatment Wetland
To improve water quality in the Lower Fox River watershed, which drains to Green Bay, the Conservancy is working with partners to design and construct up to six treatment wetlands over the next several years. Funding for the project comes from a federal Great Lakes Restoration Initiative grant, which was secured by the Fox-Wolf Watershed Alliance.

A treatment wetland is a created or re-established wetland designed to reduce a variety of pollutants including excess sediment, phosphorus and nitrogen – all of which are causing poor water quality in the Lower Fox River and Green Bay.

Runoff from agricultural fields often carries soil and nutrients that can cause water quality problems. The slow velocity of water in wetlands allows the soil and nutrients to settle to the bottom where wetland plants absorb or trap and hold them in place.

The Conservancy, Outagamie County Land Conservation Department, University of Wisconsin-Green Bay, and the U.S. Geological Survey (USGS) worked with a generous landowner to design and install a treatment wetland on his farm land along West Plum Creek near Kaukauna in August 2016. The wetland is half an acre in size and will capture the soil and nutrients from 10 acres of surface and tile drainage water with the goal of improving water quality downstream.

USGS and the Conservancy have developed extensive monitoring protocols to understand the wetland’s contribution to nutrient reduction.

“We have monitored the treatment wetland during five rain events so far, and should have results back from the lab soon that tell us how much phosphorus and sediment is being retained,” said Paul Reneau, hydrologist with the U.S. Geological Survey. “One benefit of the wetland we can already see is that about 250,000 gallons of water was temporarily stored in the wetland during each rain event. Less water in West Plum Creek means the water is moving slower, causing less soil erosion and contributing fewer nutrients to that creek and downstream in the Fox River.”

The goal of the pilot project is to better understand the ability of treatment wetlands to manage nutrients and soil in this watershed, which is largely dominated by agriculture. We will use what we learn here to improve the design of future treatment wetlands in the watershed.

If the data show that treatment wetlands are an effective way to reduce soil and nutrient loss to streams, we will work with county conservation staff to share the information with landowners through personal visits, tours, and other outreach events.

“Similar to cover crops, we hope that treatment wetlands will be another strategy landowners can use to reduce soil and nutrient loss in runoff,” said Van Helden. “If so, the next step is getting the word out to generate interest and give landowners enough confidence to consider installing a treatment wetland on their land.”

Silver Creek Wetland Restoration
Using a Fund for Lake Michigan grant, the Conservancy is working on a pilot project with the Oneida Nation, NEW Water and UW-Green Bay to improve soil health, restore wetlands and grasslands and improve water quality using an ecosystem approach.

The project is taking place on land owned by the Oneida Nation in Brown County. The land drains to Silver Creek, a tributary of Duck Creek that flows into the bay of Green Bay. The collaborative project will demonstrate how restoring a wetland can help filter the nutrients and sediment from farms so that cleaner water flows into Lake Michigan

The first step of restoration began in the summer of 2015, when the Oneida Nation controlled invasive plants in the existing wetland and the adjacent 80-acre farm field was converted to permanent cover to improve water quality draining toward the wetland and Silver Creek. This year, we plan to restore the wetlands on site to favor native vegetation and appropriate wildlife habitat and adjust the site’s hydrology, which has been altered by ditching, to improve surface water quality.

This project is part of the larger Silver Creek Pilot Project, a collaborative effort led by NEW Water (the brand of the Green Bay Metropolitan Sewage District), to reduce phosphorus discharge to the Fox River by working with the local community and utilizing an adaptive management approach. The overarching goal of the pilot is to implement a set of agricultural conservation practices and restoration projects in the watershed that will improve water quality in Silver Creek.

“We are collaborating with great partners on two projects that test strategies we hope will improve water quality, provide wildlife habitat and increase flood water storage capacity,” said Van Helden. “If successful, these strategies could become helpful tools throughout the Green Bay watershed to stop the flow of phosphorus to the Bay and reduce the occurrence of dead zones that foul our waters and keep communities from enjoying a beautiful day by the Bay.”


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