Work recently wrapped up on a $500,000 construction project in Oconomowoc to improve an unnamed stream, locally known as Cottonwood Creek.
The Oconomowoc Watershed Protection Program kicked off the stream restoration construction about 18 months ago, and finished on June 10, according to Erik Joost, watershed manager of OWPP.
He said the work will improve the water quality of the creek, which flows into Lake Lac La Belle.
“We’re in Lake Country, that speaks for itself,” Joost said. “Water quality has a huge influence on the community and culture in the area.”
Restoration project on Cottonwood Creek is connected to the entire Oconomowoc River watershed system
Cottonwood Creek is one of three tributaries of Lac La Belle. A tributary is a stream or river that flows into a larger stream, river or lake.
Lac La Belle has been designated as impaired by the Wisconsin Department of Natural Resources due to excessive phosphorus levels.
Lac La Belle is one of the 17 connected lakes in the Oconomowoc River watershed system in northern Waukesha County. The 49-mile-long system ultimately drains into the Rock River.
Here’s why Cottonwood Creek needed restoration
Cottonwood Creek is plagued by high phosphorus concentration and sediment, according to Joost.
Sediment is when naturally occurring particles like sand, clay and silt settle at the bottom of a body of water; it can become a source of pollution when excessive amounts enter waterways, according to the U.S. Environmental Protection Agency.
High phosphorus can negatively impact water quality and flow, the EPA said, because it promotes chlorophyll in the water, causes excessive algae growth and can be fatal to aquatic life. The EPA lists sediment as the most common form of pollutant in rivers, lakes and streams.
Many factors can contribute to this, including erosion from both private and public property, according to Joost. Cottonwood Creek flows through agricultural land, a golf course and a marsh before it drains into Lac La Belle.
Here’s what OWPP and partners did to lower sediment levels in Cottonwood Creek
To complete the project, OWPP worked closely with Tall Pines Conservancy, which has staff with experience in working on stream restoration.
Paul Meuer, land protection manager with Tall Pines Conservancy, said in a news release that the project will help keep Lac La Belle clean, healthy and vibrant.
He said crews used proven ecological techniques like planting native wetland vegetation to absorb excess nutrients before they reach Lac La Belle.
They also installed root wads, strong tree root systems, sometimes with the trunk of the tree still attached, along the banks to provide habitat for aquatic life and to act as a natural protection against erosion, Meuer said.
Joost said the restoration efforts will work to slow down the stream’s flow, block sediment and encourage sediment to settle out.
Overall, Cottonwood Creek will flow with curves and bends that will reduce erosion and improve drainage, the release said.
OWPP obtained a municipal flood control grant from DNR for stream restoration project funding
For this project, which Joost said cost roughly $500,000, OWPP worked with a municipal flood control grant program through the DNR. This grant offers a 50/50 cost share partnership.
The remaining funds were donated and contributed by the Lac La Belle Management District, the City of Oconomowoc, the Town of Oconomowoc, Tall Pines Conservancy and the Village of Lac La Belle.
Part of the OWPP’s mission is to work closely with farmers. When Joost started as a watershed manager with the OWPP two years ago, one of the first farmers he met told him about the erosion he had noticed on Cottonwood Creek and asked for some help.
Shortly after, OWPP started looking into different options, talking to stream engineers and identifying grants they could go after for the restoration, Joost said.
Six months later, OWPP was approved for the grant. They then moved into the permitting and design process, and construction has taken place for the past 18 months.
OWPP’s mission is to work in partnership to protect and improve water quality in the Oconomowoc River watershed.
“I grew up fishing these lakes and rivers, and I love the waters of Lake Country,” Joost said. “I recreate on them, I appreciate them for just how pristine they generally are. It’s a resource that’s not commonly found. It’s just a special area.”
Liliana Fannin is a 2025 summer intern at the Milwaukee Journal Sentinel covering the Milwaukee suburbs. Have a tip? She can be contacted at lfannin@gannett.com.
This article originally appeared on Milwaukee Journal Sentinel: Water quality improvement project to benefit Oconomowoc River watershed
Reporting by Liliana Fannin, Milwaukee Journal Sentinel / Milwaukee Journal Sentinel
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