Saturday, May 24, 2025
Art Malm
Editor’s Note: Contributor Art Malm takes us on an exploration of the Fox River and the upcoming removal of one such dam that may very well settle the issue of removal for most of the rest of the dams on the Fox. Malm is a retired professional civil and environmental engineer whose fifty-year career in the fields of water pollution control and public water supply includes the construction, commissioning, and successful operation of Elgin’s Fox River water supply and much later as a trustee of the Fox River Water Reclamation District and Friend of the Fox River. And ― his home is on the Fox River.
There are no nationwide battles over river dam removal, only local. In the context of many dam removal controversies, slogans proclaiming “Save Our River, Save Our Dams” can mean “Save Our Powerboating.”
A prime example is the Illinois Fox River Dam-removal opponents’ yard signs that make the “Save Our River, Save our Dams” claims that play into public concerns about wildlife loss. These claims are contrary to experience and the consensus of scientists and environmental engineers who are informing this and other Army Corps projects. Nature time and again has demonstrated its ability to quickly turn so-called mudflats into greenery as wildlife diversity soars when dams are removed. (Check out Those Pesky Claims Made by Dam Removal Opponents.) Paddlers have a must-see opportunity all next year to witness a section of the Illinois Fox River coming back to life. The Carpentersville Dam on the Fox in northeastern Illinois is being removed, opening a 10-mile stretch of river that can be navigated without portage. The receded shoreline together with the ebb and flow of the river will provide improved public access to a naturally cleaned sand-and-stone shoreline above the old dam site. Fishing and birding will improve as the natural riverine habitat returns. Until then, the Carpentersville dam stands as a nine-foot-tall concrete wall across the Fox River. The U.S. Army Corps of Engineers (USACE) wants it removed because of its harm to the aquatic environment. The Illinois DNR wants it removed because it is a safety hazard and liability. The local Fox River Study Group wants it removed because it creates significant water quality impairments. Costs of Non-Removal The Carpentersville dam is the first demolition target in a program where the USACE is recommending removal of the nine dams on the Fox River, from Carpentersville to Montgomery. Detailed design for each removal will follow soon thereafter. Dam removals as part of this project will be funded 65% by the Corps and 35% by the IDNR, and are expected to be completed by 2030. Any community may keep its dam ― provided they take full ownership responsibility, including liability. Liability may extend to cases where injuries and deaths are caused by the dam’s powerful hydraulic forces that can trap and drown people. Ownership also includes the costs of mandated safety inspections as well as the maintenance and repair of structures that are, in most cases, over 100 years old. The Illinois DNR estimates the annualized cost of ownership, not including liability exposure, to be $125,000 per year for each of its dams. In brief eulogy, the Carpentersville Dam was first built as a brush pile dam in 1838. The land had just been opened for settlement by the Federal government following the end of the Blackhawk War. The dam’s first jobs were to mill flour and cut lumber. Later, the dam provided waterpower to a foundry and drove a hydroelectric plant. Both purposes ceased operations long ago. The Carpentersville Dam is the first of nine such dams on the Fox River currently recommended for removal by the Army Corps of Engineers and Illinois DNR before 2030. The success of the Carpentersville Dam removal should help local officials accept the 100 percent State and Federal funding that has been offered to remove any or all the remaining eight dams on the Fox, from Elgin to Montgomery, a potential rewilding of the Fox without portage for nearly forty-five miles of river and floodplain. Fox Rocks History The Fox River is largely the work of glaciers over the past 100,000 years. Above and throughout the rolling valleys of limestone bedrock underlying the Fox River Valley is a mix of soils bulldozed from Wisconsin by glacial ice and meltwaters. The material left behind is known as “glacial till.” As the glaciers melted, the till eroded. Light materials, silts and clays, were swept downstream and out of the watershed. Heavier materials became the river bottom in the bedrock crevices, often sorted into lenses of sand, gravel, and rock. This glacial cycle repeated itself at least three times over the past 100,000 years, giving the Fox its natural sand and rock bottom. The Fox River pathway south from Wisconsin is defined by two principal moraines of till left by the great Wisconsonian glacier that parallel the Lake Michigan shoreline. The Marengo Moraine became the western boundary of the Fox watershed about 25,000 years ago. The Valparaiso Moraine, the eastern, left when the last glacier melted 10,000 years ago. To better appreciate the uniqueness of the Fox River and its valley, hosting 153 State threatened or endangered species, you need to go back nearly 450 million years, when the Fox River Valley was beneath a warm shallow sea. For tens of millions of years, great coral reefs grew at the bottom of that sea. The ocean floor rose and became land. The land split, forming the great continents with the Atlantic Ocean in between. With aging and pressure over those hundreds of millions of years, the calcium-rich corals would compress to become the thick calcium-rich limestone bedrock that today underlies the Fox River Valley and its tributaries. On an average day at its midpoint, the Fox River will carry away in its waters over a million pounds of dissolved limestone rock, giving the Fox a hardwater chemistry that has provided nutrition to a large and diverse population of the Valley’s inhabitants. That included the calcium needed to build the shells of the Fox’s once-abundant native mussel communities and the calcium needed by its cows to produce milk in quantities that made Elgin the largest milk town in the Midwest between 1880 and 1910. With its ancient underlying limestone base, as well as its confinement between two north/south-oriented glacial moraines, this young river offers a unique character to be explored and treasured. Paddling Downriver From southeastern Wisconsin to the Chain O’ Lakes, the Fox is a sleepy river passing through what was naturally marshland. Wisconsin boaters look at the Illinois Fox and see a small river with two nice lakes that meanders south across the state line into the Illinois Chain O’Lakes. The natural river bottom from Stratton drops 10 feet in the next 15 miles to Algonquin. This stretch carries heavy, high-horsepower boat traffic and as a result can be treacherous water for paddlesports. At Algonquin, the powerboats disappear and the underlying geology of the river begins to change. This is the stretch above the Carpentersville dam that will be returning to its natural channel and shorelines. The newer, harder bedrock underlying the river to the north starts to disappear along this reach, exposing an older, softer, and more erodible bedrock. The riverbed slightly steepens. The Fox is a shallow, normally slow-moving warm-water river. In the 4.4 miles from Algonquin to Carpentersville, the river drops 8.1 feet, not quite two feet per mile. This can be compared to the average 8-feet-per-mile slope of the Colorado River through the Grand Canyon, or whitewater rafting the Yellowstone River with riverbed slopes above 20 feet per mile. This relatively small slope doesn’t mean the Fox is naturally stagnant by any means. At its midpoint, the Fox River on average carries enough water to fill an empty Olympic-sized swimming pool every minute of the day. Before the dams, when allowed to flow naturally, the Fox River had been a series of riffles, runs, and shallow pools with a natural sand-and-rock bottom, not mud as many believe. As dams are removed, much of the sediment now in the impoundments behind the dams will drain and become grassland. With narrower banks and higher velocities, the river will be able to scour-clean much of its bottom and shoreline. Some of the sand and small stones that accumulated behind the dam over the decades will be released. These sediments will become natural sandbars as they move slowly downstream, providing a new habitat for fish, mussels, and boaters. Paddling Onward As you finish your 10-mile paddle south from Algonquin to the Elgin Dam, the slope of the river remains at about 2 feet per mile, with an average depth of about three feet and maybe some excitement where the river drops past the old dam site. Beyond Elgin, the Fox begins to expose its underlying limestone for the first time as the river runs through what is known as the St. Charles Valley. Still farther south on its path to confluence with the Illinois River in Ottawa, the Fox passes sandstone outcroppings, part of a complex geologic puzzle with a history of its own. No one knows exactly what the restored riverbed will look like after the 378-foot-long concrete monolith in Carpentersville is removed. The best data suggests that the river will have primary and secondary channels upstream, much like what is seen downstream today. In any event, paddlers enjoying the river will see the progressive wilding of the river throughout the next year and beyond. Whether there will be new whitewater for kayakers to hang out and play or a long, broad riffle at or near the dam site is a matter of speculation. Time will tell. Tomorrow, with the Carpentersville dam’s removal, the memory of the river’s blockage will fade as the Fox returns to the channel it spent the last 25,000 years creating. For more information about paddling the Fox River, go to the Fabulous Fox! Water Trail website at fabulousfoxwatertrail.org, where maps, including current access sites, can be downloaded. RELATED ARTICLE: Those Pesky Claims Made by Dam Removal Opponents
Comments
No comments on this item Please log in to comment by clicking here