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ROCK RIVER

River Levels • Streamflow • Hydrology

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Total streamflow across the Rock River was last observed at 29,436 cfs, and is expected to yield approximately 58,386 acre-ft of water today; about 99% of normal. Average streamflow for this time of year is 29,729 cfs, with recent peaks last observed on 2019-03-16 when daily discharge volume was observed at 188,530 cfs.

Maximum discharge along the river is currently at the Rock River Near Joslin reporting a streamflow rate of 7,500 cfs. However, the streamgauge with the highest stage along the river is the Rock River At Robert Street At Fort Atkinson with a gauge stage of 11.38 ft. This river is monitored from 10 different streamgauging stations along the Rock River, the highest being situated at an altitude of 1,316 ft, the Rock River Below Tom Creek At Rock Rapids.

The Rock River is a tributary of the Mississippi River that flows through Wisconsin and Illinois. The river is approximately 299 miles long, originating in Horicon Marsh, Wisconsin, and flowing south into Illinois, where it eventually empties into the Mississippi River near Rock Island. The river has played a significant role in the history of the region, serving as a transportation route for Native American tribes and European settlers. The river is also a popular destination for recreational activities, including fishing, boating, and canoeing. Several reservoirs and dams along the river, including the Lake Koshkonong Dam and the Rockford Dam, provide hydroelectric power and flood control. The river is also used for agricultural purposes, with many farms located along its banks.

November 21, 2024

Last Updated	2024-11-20
Discharge Volume	58,386 ACRE-FT
Streamflow	29,436.0 cfs +1734.0 cfs (+6.26%)
Percent of Normal	99.01%
Maximum	188,530.0 cfs 2019-03-16
Seasonal Avg	29,729 cfs

History of the River

The Rock River is a tributary of the Mississippi River, approximately 299 miles (481 km) long, in the U.S. states of Wisconsin and Illinois. The river was known as the Sinnissippi to Sauk and Fox Indians; the name means "rocky waters".The river begins with three separate branches which flow into the Horicon Marsh. The northernmost branch, the West Branch, begins just to the west of the village of Brandon in Fond du Lac County, Wisconsin and flows east and then south to Horicon Marsh. The South Branch rises north of Fox Lake in Dodge County and flows east through Waupun to the marsh. The East Branch rises southeast of Allenton in Washington County just west of the Niagara Escarpment, and flows north and west through Theresa to the marsh.
Leaving the marsh, it meanders southward to the Illinois border ending about 300 miles later at the Mississippi River at the Quad Cities in Illinois and Iowa. During its course it passes through Watertown, collects the Crawfish River in Jefferson, and receives the Bark River at Fort Atkinson. Shortly before merging, the Rock and Crawfish rivers cross Interstate 94. Both rivers flood the nearby land regularly, and lanes on I-94 were temporarily closed in 2008 because of this flooding.In northern Rock County it receives the Yahara River, and flows southward through Janesville and Beloit into northern Illinois, where it receives the Pecatonica River 5 miles (8 km) south of the state line. It flows south through Rockford, then southwest across northwestern Illinois, picking up the Kishwaukee River, passing Oregon, Dixon, Sterling (which has the Sinnissippi Mounds national historic site and local park) and Rock Falls before joining the Mississippi at Rock Island. It was on the Rock River in Dixon where Ronald Reagan was a lifeguard. Reagan's favorite fishing spot, now called "Dutch Landing" after Reagan's nickname, was just southwest of Lowell Park on the Rock River.
There are 23 dams on the Rock River. These are in Theresa (WI, 3 dams), Waupun (WI), Horicon (WI), Hustisford (WI), Watertown (WI, 2 dams), Jefferson (WI, 4 dams), Indianford (WI), Janesville (WI, 2 dams), Beloit (WI), Rockton (IL), Rockford Fordham (IL), Oregon (IL), Dixon (IL), Sterling / Rock Falls (IL, 2 dams), Milan (IL) and Rock Island (IL).

The river is used for various water and paddling sports. The Rock River Water Trail is on the river from its headwaters above the Horicon National Wildlife Refuge in south central Wisconsin to the confluence with the Mississippi River at the Quad Cities of Illinois and Iowa 330 miles downriver. It crosses five counties in Wisconsin, six counties in Illinois and runs through 37 municipalities. The slow moving river passes scenic rural landscapes, wilderness areas and urban areas. The first two trailheads are at Waupun County Park in Waupun, Wisconsin and Rivers Edge Park in Theresa, Wisconsin and there are 32 additional access points in Dodge County, Wisconsin. The trail is part of the National Water Trails System and the first National Water Trail in Wisconsin and Illinois.Rock River Park is on County Road B about a half mile west of Johnson Creek, Wisconsin in Jefferson County, Wisconsin and offers river access and an artesian spring.