|Volunteers from TU's Lakeshore Chapter pull flashboards from a dam, draining a former hatchery pond. The Silver Springs project is restoring coldwater habitat in the Onion River's headwaters. (Wisconsin DNR photo)|
Years of human alteration to the headwaters of the Onion River have contributed to the river's degraded capacity to support a sustainable, reproducing native fish population. At one headwater site, Silver Springs, a defunct fish hatchery left behind a riddle of underground pipes, concrete raceways and artificial ponds over a complex of clean, cold, forested springs. The purchase of the site by a private corporation enabled a partnership between the Wisconsin Department of Natural Resources (WDNR), Trout Unlimited National, Windway Capital Corporation and TU's Lakeshore Chapter to restore the forested wetland and high-quality habitat for coldwater fish.
|Hatchery ponds in Silver Springs give it the look of a golf course in reverse. The ponds cover two tributaries that once supported coldwater habitat. (Wisconsin DNR photo)|
The River and Site
The Onion River is a 100-square-mile watershed in eastern Wisconsin, which flows into the Sheboygan River and ultimately to Lake Michigan. The Onion was one of the first rivers included in Wisconsin's Priority Watershed Program, which strives to manage nonpoint source pollution. Although nonpoint pollution from agricultural and urban runoff throughout the watershed degrades its habitat quality, the WDNR cites headwater alterations by hatcheries as an additional contributing factor. Because of the various impacts, the Onion River is no longer able to naturally support a reproducing trout population.
Silver Springs, part of the headwaters of the Onion, is an extensive spring complex including two small tributaries. The tributaries become Mill Creek before flowing to the Onion. Crystal-clear, cold spring water bubbles up in Silver Springs in forested uplands among watercress and wetland grasses. In the 1930s, the site was converted to a private fish farming operation, raising trout and some warmwater fish. In the late 1980s, the hatchery was no longer economically viable and the operation was abandoned.
Dam Removal Facts
Dimensions: Height - 4 to 8 ft.; Length - varies
Built: The dams were built along with expansion of hatchery operations, beginning in the 1930s.
Purpose: Provide hatchery holding ponds
Estimated cost of dam removals: $30,000
Estimated cost of restoration (including dam removals): $75,000
Removal date: Summer 2002
Removal method: Backhoe
The Impact Prior to Removal
An array of alterations to the natural features of the site was left behind when the hatchery was abandoned. The springs were made to flow through underground pipes, tanks in a hatchery house, concrete raceways, more pipes, rearing ponds and several dams and control structures before reaching Mill Creek. Ten holdings ponds were separated by constructed earthen berms. The ponds raised naturally cold, spring-fed stream temperatures by as much as 20 degrees F in summer. This warming degraded natural coldwater habitat downstream. The ponds were maintained by dams, ranging four to eight feet in height with wood or concrete control structures, which prevented fish passage.
The Removal Decision and Process
For several years, TU's Lakeshore Chapter and the WDNR have been working on conservation efforts along the Onion River. When property in the Onion's headwaters, including the Silver Springs complex, came up for sale, one of the Chapter's members took note. He approached a fellow chapter member, the owner of Windway Capital Corporation, and suggested the possibility of purchasing the land. Windway's owner had fished the Onion River as a child and decided to purchase two parcels of land comprising 385 acres for the purpose of their restoration and conservation.
Lakeshore Chapter volunteers began pre-monitoring efforts to track the progress of work done at the site. Their baseline channel surveys included measurements of stream temperatures, benthic macroinvertebrates, and fisheries. In 1999, chapter members pulled the flashboards out of the dams at Silver Springs, draining several of the ponds.
Later in 1999, the Great Lakes Protection Fund awarded a $312,000 grant to Trout Unlimited to restore Silver Springs and two other sites, highlighting the dam removals as demonstration projects for the Great Lakes Basin. The WDNR is providing additional funding through Wisconsin Trout Stamp Funds. In total, the Silver Springs restoration project is expected to cost approximately $75,000, including the cost to remove the dams. The dam removals alone are expected to cost approximately $30,000.
In 2000, Trout Unlimited, the WDNR, the River Alliance of Wisconsin, and a private consultant, NES Ecological Services, began formulating specific plans to remove the various hatchery structures and restore both the stream channel and a forested wetland at the site.
Restoration of the River
Channel restoration work is scheduled to begin in spring 2002. All of the hatchery structures will be removed, including underground pipes, raceways, and dams. A more natural stream channel will be re-formed through the drained ponds, carrying the clean and cold springflow to the Onion River.
The restored channel is being designed to simulate a natural meandering stream, with habitat features for trout spawning and rearing, as well as for other native species. Channel banks will be seeded with native plants to provide stability and additional habitat for floodplain species. Ultimately, much of the area will be restored to a forested wetland adjacent to the redesigned channels.
Future Efforts to Restore the River
To ensure the long-term preservation of the Silver Springs area, the WDNR is planning to purchase 135 acres from Windway Capital through the Warren Knowles - Gaylord Nelson Stewardship Program. TU's Lakeshore Chapter joined other conservation groups to donate $35,000 to help fund the purchase, which is expected to be approximately $800,000.
The Onion River will continue to be a focus of conservation efforts by the WDNR and TU. TU's Lakeshore Chapter recently received a $1,250 grant from TU's Embrace-A-Stream program for continued monitoring of water quality, temperature, aquatic insects, and fish populations in the river.
The Significance of this Removal
Along with other restoration projects in the watershed, the Silver Springs restoration is expected to help restore natural reproduction of coldwater species, including native brook trout, in the Onion River watershed. Headwater restoration projects such as this one are crucial to restoring the health of river systems and the entire Great Lakes Basin. The project is also restoring important spring-fed forested wetland habitat. The wetland and stream channel restoration together demonstrate the importance of recognizing the interconnectedness between land and water for restoring and maintaining ecosystem health.
Perhaps most significantly, the Silver Springs restoration project illustrates how volunteers can play a valuable role in initiating headwaters restoration and the legacy that a concerned philanthropist can leave by supporting conservation efforts.