Upper Rock River Basin

Rock River State of the Basin Overview and Watershed Reports

For more information on the plan, contact the Upper Rock River Basin Water Team Leader, Jim Congdon, who is located in the WDNR South Central Region's Horicon Office in Horicon, WI. (920-387-7872).

The information on this website, unless otherwise indicated, is from the 1995 Upper Rock River Basin Water Quality Management Plan. Click on the map for a larger version...to access information by watershed

The Upper Rock River basin, covering 1,890 square miles, lies in south central Wisconsin's eastern ridges and lowlands geographical province (Martin, 1932). At the north end of the basin, the East, South and West branches of the Rock River come together in Horicon Marsh. From the city of Horicon, on the south edge of the marsh, the river flows south 76 miles to Fort Atkinson. The remainder of the Rock River mainstem, 62 miles, is in the Lower Rock River Basin, which extends from Fort Atkinson to the Wisconsin-Illinois border. The gradient of the Upper Rock River is very flat. The fall of the river from the upper Federal dam in the Horicon National Wildlife Refuge to the upper Watertown dam is just 34 feet over 58 miles.

The basin is bounded on the east by the Niagara escarpment and the eastern terminal moraine, formed by the Green Bay lobe during the last glaciated period in Wisconsin. The most dominant geologic features are the extensive drumlin fields in Dodge County and portions of Dane, Columbia and Jefferson counties. Principal soil types in this region are Dodge, Miami, Morley, Casco, Plano, Warsaw and Varna soil associations in upland areas. Soil associations in wetland areas are Pella, Poygan and Brookston (Hole, 1976). These soils are fertile and productive.

The largest water features in the basin are the Rock River, the Crawfish River, the Beaver Dam River, Horicon Marsh, Beaver Dam Lake, Lake Sinissippi and Oconomowoc Lake. Municipalities with populations over 5,000 are Watertown, Beaver Dam, Oconomowoc, Waupun, Hartford and Jefferson.

Most of the original wetlands in the basin have been drained for agriculture or filled for development. However, many wetland complexes remain. The largest of these is Horicon Marsh in Dodge County. The marsh is owned by the State of Wisconsin and the U.S. Fish and Wildlife Service. Other large wetland complexes include: Theresa Marsh, Deansville Marsh, Portland Marsh, and the wetlands in the Mud Lake State Wildlife Area. Many of the larger wetlands are part of state wildlife areas.

Agriculture, the predominant land use, includes a mix of dairy, feeder operations, cash-cropping and muck farming. Dodge County, most of which lies within the basin, is the state's leading producer of green peas, sweet corn for processing and corn for silage. Dodge County also ranks forth in the state for total number of cattle and calves, and fifth for hogs and pigs (USDA, 1994).

Surface Water Quality Problems

The primary water quality problems in impoundments the Upper Rock River Basin, excessive growth of algae, reduced dissolved oxygen levels, and poor water clarity (turbidity), are caused by agricultural and urban polluted runoff, which contribute thousands of tons of sediment and nutrients to surface waters annually.

Urbanization has also affected the basin's lakes during the past 50 years. The pressure of urbanization is ongoing, as most municipalities in the basin try to attract new commercial, industrial and residential development. Most lakes in the basin are very fertile, shallow, and eutrophic or hypereutrophic (excessive growth of algae, often "pea green" in color). The lakes are generally very turbid or experience excessive aquatic plant growth and/or algae blooms. As explained above, the high fertility is due in part to excess sediments and nutrients from polluted runoff. Polluted runoff may have substantially greater impacts to small, shallow lakes, than to larger, deeper lakes. However, lakes that are deeper and borderline mesotrophic, such as Rock Lake, Lac LaBelle, Okauchee Lake and North Lake, merit additional protection to halt or slow water quality declines.

Excess sediment that settles on the river and lake bottom smothers macroinvertebrates and fresh water mussels, clogs up rocky substrate necessary for aquatic habitat, and increases the turbidity of the water column. Sediment that reaches streams and lakes may also carry nutrients and heavy metals. Excess nutrients can result in excessive growth of algae or floating aquatic plants (macrophytes), which in turn can limit light penetration at depth and thus reduce the production of oxygen by submergent and emergent macrophytes. The decomposition of algae after a bloom also robs the water column of dissolved oxygen needed by aquatic organisms, including fish.

Heavy metals delivered to surface waters from polluted runoff or direct discharges may contribute to the presence of toxicity of the receiving water, depending on a number of variables (pH, dissolved oxygen levels, etc.).

Activities that contribute polluted runoff include:

cropland erosion
streambank erosion
heavy concentrations of livestock
barnyards and feedlots located next to streams
inadequate erosion control at construction sites
unmanaged urban stormwater runoff

Other problems affecting water quality are due to alterations -- particularly the channelization, or straightening, of smaller streams and the drainage of wetlands. Excessive populations of rough fish usually inhabit degraded aquatic environments, as they are able to outcompete more sensitive fish in the murky environs. Rough fish such as carp contribute to the overall water quality problem by removing aquatic plants that help secure sediment to the river or lake bottom. Even though the Upper Rock River supports a diverse warmwater sport fishery, rough fish, millponds, and polluted runoff have degraded its quality substantially.

Three watersheds are recommended as high priority candidates for selection as priority watershed projects under the state's nonpoint source pollution abatement program. Those three are the East Branch of the Rock River in Washington and Dodge counties, Upper Rock River watershed in Dodge and Fond du Lac counties, and Upper Crawfish River watershed in Columbia County. In addition two lakes and their subwatersheds are recommended for small-scale priority watershed project selection. They are Pike Lake in Washington County and Rock Lake in Jefferson County.

Impoundments

There about 80 impoundments (includes millponds) in the Upper Rock River and its tributaries (Joseff, 1994). At least 30 impoundments are in state or federal wildlife areas and are managed to promote migratory waterfowl use. The remainder are formed by either small hydropower dams or old mill dams that form "millponds" of varying size. None of the impoundments in the Upper Rock River basin were designed for flood control and the majority have very little flood storage potential. Most impoundments are operated as "run-of-the-river" (Joseff, 1994). WDNR Southern District Water Regulation and Zoning staff have made a number of recommendations pertaining to the operation dams in this basin (Joseff, 1994). Both impoundments and millponds display similar water quality problems (Marshall, 1988).

Millponds

Millponds in the Rock River system have become degraded and filled with carp and sediment (Bush, 1994). Millponds are common in south and southwestern Wisconsin. Dating back to the mid-to-late 1800s, dams were built and maintained for flood control, grain milling,and logging. In the 1900s, many millpond dams were built or modified to provide hydropower. Over the decades, millponds have become important recreational and aesthetic resources to communities in which they exist. However, because of their special physical characteristics, millponds require intensive management to maintain moderate water quality. Millponds tend to experience sedimentation, unbalanced populations of rough fish, turbidity, excessive algae blooms and/or high concentrations of "weed" macrophytes. Several alternatives exist for managing these problems, including drawdowns, shading/sediment covers, and harvesting macrophytes. Long-term management solutions include dredging, dam removal, and lake management planning. The WDNR shallow lakes (Lakes Program) and carp management (Fisheries Management) initiatives are addressing problems associated with impoundments.

Recommendations

WRM, WRZ, and FM should assess potential water resource impacts from human-altered hydroregimes, including poor water quality and degraded aquatic habitat, in the Upper Rock River Basin (Type B).
Impoundments with poor water quality and degraded aquatic habitat that may be attributed to the presence of water control structures, and which serve no significant water resource purpose, should be evaluated for alternative management actions, including dam removal (Type B).

Map of Basin

Last Revised: Wednesday August 09 2006