Two Chicago area rivers, the Des Plaines and Fox, had 25 dams, most of which were built 100 or more years ago for agricultural, sanitary, or transportation purposes -- in most cases, purposes no longer relevant. Most, like this dam on the Des Plaines River in Lake County's Dan Wright Forest Preserve, are low-head dams, probably built by a local owner for agricultural reasons -- to pool water for irrigation, or to facilitate getting farm machinery across the river before the suburban sprawl resulted in numerous bridges being built. This dam is 140 feet across, two feet tall, and has a 25 foot concrete apron on the low side. I've kayaked and canoed over it half a dozen times while participating in the annual Des Plaines River Canoe Marathon. Years ago, a V-shaped notch was cut in the dam to assist paddle craft heading downriver. You can see the V-cut near the middle, to the right of the mid-river green algae bloom.
Many paddlers, unaware of the V or unable to get their boat into it, had problems. But there are other problems created by the dams. They prevent movement of fish and other aquatic life upriver and downriver, the pools created cause oxygen levels to fluctuate and create over-abundance of algae, river banks deteriorate, and flora and fauna suffer. Water quality in the rivers dramatically improve when the river returns to free-flowing status.
When the dam was removed in Riverside in 2012, the number of fish found upstream doubled, and the number of species rose from 6 to 29 in just weeks. Now 70 species make their home in the river!
The State of Illinois has been funding dam removal, but the state's dire financial straits from having no budget approved for two years has left the removal projects unfunded. The Forest Preserve District of Lake County has fronted the cost of two dam removals to the tune of about 3/4 million dollars and might see the money recouped in the future, but they aren't counting on it.
Here are a few photos of the dam removal in progress during 2015 and 2016. I took these from the Des Plaines River Trail bridge which is just a 100 or so feet downriver from the Dan Wright Woods dam. In the photo below you see work on the east end of the dam...
...and last year they removed the west end of the dam...
Today I took the "finished" photo seen below, and with this dam removed, the canoe marathon this year, for the first time in its 60 year history, had an unobstructed river for the entire 18.5 mile course!
INTERESTING NOTE: Nationwide, 72 dams were removed in 2014 which opened up 730 miles of waterway. In the last 20 years, 971 of 1185 American dams have been removed!