|A small dam blocks fish passage on an unnamed tributary to the Onion River. Dams and diversions have contributed to degrading coldwater habitat in the Onion's headwaters. (Trout Unlimited photo)|
The Onion River once supported a population of native brook trout and other coldwater species, but human activities, including alteration of the river's headwaters, have left it unable to sustain natural reproduction of those species. Trout Unlimited's Lakeshore Chapter, the Wisconsin Department of Natural Resources (WDNR) and Trout Unlimited National (TU) have recently begun restoration projects along the Onion and its tributaries with the goal of restoring the river's natural habitat. The Kamrath site, in the headwaters of the Onion, once provided important spawning and rearing habitat, but dams and stream diversions warmed the water and blocked fish passage. Restoration of the site was made possible when a private company, Windway Capital Corporation, purchased the land for the purpose of restoration and future conservation. With the support of the Great Lakes Protection Fund, Trout Unlimited designated the Kamrath site a dam removal demonstration project and worked with the WDNR to restore the site's natural coldwater habitat.
Dam Removal Facts
Estimated cost of dam removals: $10,000
Estimated cost of restoration (including dam removals): $77,000
Upstream concrete dam
Dimensions: Height - 5 ft.; Length - 15 ft.
Purpose: Part of hatchery operation
Removal date: April 2001
Downstream earthen dam
Dimensions: Height - 12 ft; Length - 300 ft.
Removal date: Summer 1999
Removal method: Backhoe
The River and Site
The Kamrath restoration site lies in a rural area of eastern Wisconsin near the town of Plymouth. The site is primarily forested upland adjacent to some cropland and pasture. Kamrath's creek is an unnamed tributary of the Onion River, which ultimately flows into the Sheboygan River and Lake Michigan. The creek flows directly into Ben Nutt Creek before reaching the Onion. Under natural conditions, the stream carries mostly clear and cold springflow. Historically, the stream flowed east directly to Ben Nutt Creek, but in the 1950s, it was moved to flow through two small artificial ponds. The upper 8-acre pond was used to exercise and rehabilitate horses from a nearby stable. The lower 4-acre pond was dammed by a 12-foot high earthen structure, adjacent to a county highway, and its original purpose is currently unknown. A fish hatchery operation constructed a separate small dam further upstream, near where the stream was diverted.
The Impact Prior to Removal
Prior to the 1940s, the Onion River was a blue ribbon trout fishery. However, years of nonpoint source pollution from agricultural and urban runoff and degradation of its headwaters have impacted it so that it no longer supports reproducing trout populations. The Onion River is now classified by the WDNR as a Class II trout stream, meaning that trout can live in the river, but cannot sustainably reproduce.
Prior to restoration work, the Kamrath stream flowed over a small dam, through two artificial ponds connected by a culvert, and then through a control structure and culvert under a county highway before flowing into Ben Nutt Creek. Standing impounded in the two ponds warmed the spring-fed stream, particularly during the summer months. This warming degraded the stream's ability to support its natural spawning and rearing habitat for brown trout and native brook trout, which need cold water to survive. High flow velocities in the culverts and the presence of the dams both acted as barriers to fish passage.
The Removal Decision and Process
In 1999, Windway Capital Corporation, a private company, purchased 385 acres of land, including the Kamrath site, for the purpose of restoring trout habitat in the Onion River's headwaters. Windway's owner, a member of TU's Lakeshore Chapter, had fished the Onion River as a child and decided to purchase the property after another member of the Lakeshore Chapter made him aware that it was for sale, presenting a conservation opportunity.
The WDNR soon conceptualized a plan to restore the area and turned to TU National for additional funding and assistance. Later in 1999, the Great Lakes Protection Fund awarded TU National a $312,000 grant for this and two other nearby restoration/dam removal projects. $55,000 from the grant is being used for restoration and dam removal at the Kamrath site. The WDNR is also providing funding through Wisconsin Trout Stamp Funds and the Sheboygan Highway Department contributed to the removal of the lower dam. The total project cost, including channel restoration and dam removals, is estimated to be approximately $77,000. The project is expected to reduce thermal and nonpoint pollution and restore access to spawning and rearing habitat for brown and native brook trout. In May 1999, soon after the land was purchased, the lower 4-acre pond was drained. Its 12-foot high earthen dam was removed using heavy construction equipment. The upstream dam was removed in April 2001.
|Lakeshore Chapter members cut willow and dogwood livestakes for planting along Kamrath's restored channel. The livestakes will grow into full trees, reducing erosion on the stream banks and providing cover and shade for fish. (Photo by Marty Melchior)|
Restoration of the River
Although the project includes two dam removals, the bulk of the work at the site consists of re-forming the channel through the drained impoundment and reconnecting the channel back to its natural pattern from where it was diverted fifty years ago.
The restoration is a collaborative effort of the WDNR, TU National, TU's Lakeshore Chapter, the River Alliance of Wisconsin, and a restoration consultant from NES Ecological Services. The channel restoration is incorporating geomorphic and bioengineering techniques to restore natural stream function and habitat. Much of the restored channel was modeled after historical air photos. The stream is being routed back around the 8-acre upper pond and through the drained bed of the 4-acre pond, with a pattern approximating its natural meandering form. An earthen berm was removed where the restored stream enters the drained impoundment to reduce the slope of channel and increase its natural stability.
Denuded areas along the stream banks are being replanted with native seeds for habitat and bank stability. In addition, volunteers from TU's Lakeshore Chapter cut and bundled willow and dogwood livestakes from nearby growth for planting along the banks. The livestakes will quickly sprout dense roots, providing stability to the channel banks.
Future Efforts to Restore the River
After restoration and conservation plans were in place, Windway Capital sold 127 acres of land at the Kamrath site to the WDNR for its long-term conservation. The Lakeshore Chapter donated $2,000 to the WDNR to help fund the purchase. Fish passage will be restored up to the source of the creek after a 60-foot long culvert is removed that currently carries the flow from the drained impoundment to reaches downstream. High velocity flows through the culvert act as a barrier to fish. The restored channel may be stocked initially with native brook trout to give a jumpstart to what hopefully will become a naturally reproducing population.
The Significance of this Removal
Current restoration projects in the Onion River system will go a long way to restoring the natural integrity of the river and its fish populations. The Kamrath restoration project is significant because it is restoring crucial habitat in the headwaters of a coldwater fishery. Such headwater restorations are crucial to the health of river systems and the entire Great Lakes Basin. TU is using the restoration as a demonstration project to highlight dam removal and natural channel design processes.
Just as importantly, the project was able to move forward because of the foresight and stewardship of TU's Lakeshore Chapter and a generous act by one of its members. Windway Capital Corporation's owner was recently awarded the Resource Award of Merit by TU's Wisconsin Council for his part in restoring the Onion River's headwaters.