Figure 1. Left - Drakes Dam before the rock ramp was constructed. Photo: Nate Caswell, USFWS. Right – Illinois DNR Streams Specialist Robert Rung examines the crest of the new rock ramp at Drakes Dam. - Photo by Steve Pescitelli, Illinois DNR

Figure 2. Top – Photo of Harrington Dam and water control structure. Photo: Nate Caswell, USFWS. Lower left – The outlet of the new bypass channel is visible below the toe of Harrington Dam. Photo: Steve Pescitelli, IDNR. Lower right – IDNR Streams Specialist Robert Rung examines the Harrington Dam bypass channel. - Photo by Steve Pescitelli, Illinois DNR

Carterville FRO, with funding from the Service’s National Fish Passage Program, has partnered with the Illinois Department of Natural Resources, Conservation Foundation, Big Rock Creek Watershed Committee, the City of Plano, and Mr. and Mrs. Roy Harrington to provide fish passage on Big Rock Creek. 

Big Rock Creek, located in Kane and Kendall Counties in northeastern Illinois is a rural stream in a rapidly expanding urban area, and one of the larger tributaries of the Fox River.  Based on recent Illinois DNR fish and mussel surveys, this creek is one of Illinois’ highest quality streams.  Results of a 2002-2003 biological survey resulted in all mainstem sampling stations receiving an “A” rating, described by the Illinois Biological Stream Characterization as a “Unique Aquatic Resource.” 

The creek has an excellent smallmouth bass fishery, and is home to the Illinois State endangered greater redhorse and Illinois State threatened spike mussel.  Two dams, Drake’s Dam and Harrington Dam, in the lower section of the creek were the only in-stream structures known to block fish movement. 

The dams block fish throughout most of the year, and affect the distribution of several species.  Greater redhorse, channel catfish, and mottled sculpins were absent upstream of the dams, and other migratory suckers were in low abundance.  In addition, miles of the creek dried up during the 2004 and 2005 droughts, threatening the loss of other upstream fish and mussel species.  With the dams in place there was no way for these species to return from downstream sources when water levels improved. 

The first phase of the project was construction of a rock ramp at Plano Dam (Figure 1).  The job took three days and 1,300 tons of rock up to 3 feet in diameter.  According to Illinois DNR Streams Specialist Steve Pescitelli, fish started trying to pass right away, swimming through high gradient areas even before the ramp was finished.  A bluntnose minnow was the first fish observed passing the dam.  Smallmouth bass, shorthead redhorse and northern hogsuckers were also observed on the ramp before construction was even complete.

The second phase of the project was the construction of a bypass channel around Harrington Dam, a privately owned dam used to feed water to off-channel ponds (Figure 2).  Because the owner did not want the water level in his ponds to be affected by the project, notching and ramping of the dam was not a feasible alternative.  The upper end of the bypass channel is at the same elevation as the dam, so it is designed primarily to work under high flows during the spring when fish are migrating.

The Illinois DNR has been working to evaluate the effectiveness of the two structures.  Several hundred individuals of the larger, more mobile species (e.g. shorthead redhorse) have been tagged below the structures to determine whether they are able to pass.  A few of these fish have been recaptured, and a number of minnows and darters have been observed actually living in the ramp itself.  Evaluation of these structures will continue for several years.

Big Rock Creek is a unique system that has remained a high-quality resource in the face of heavy agriculture and development pressure.  Restoring fish passage at these dams reconnected 69 miles of perennial streams to the Fox River.  It opened the watershed for use as spawning and nursery habitat, which will benefit not only the resident stream species, but also Fox River species. 

This project was the first of its kind for the Service’s Fish Passage Program in the state of Illinois, and it's hoped that it will serve as an example for other fish passage projects in the state.  Service staff thank all partners, especially the landowners, for their willingness to see this project through.  The project was a success, but only through the hard work and cooperation of the many people involved.  Service staff also thank Illinois DNR Streams Specialist Steve Pescitelli, who was instrumental.