Proposed Fawell Dam project could help fish in DuPage River

Despite efforts to improve the West Branch of the DuPage River, parts of the waterway still are missing something: a diverse fish population.

At least a dozen species of fish that can be found downstream in Naperville are absent from the river upstream.

It turns out Fawell Dam in the McDowell Grove Forest Preserve near Naperville is preventing those fish from traveling up the river into Warrenville and beyond.

So the DuPage River Salt Creek Workgroup has approached DuPage County - which owns the dam - with a proposal to modify the structure to make it easier for fish to pass through.

Publicly owned wastewater treatment plants in DuPage are offering to pay for the project because improving the river's biodiversity could help the facilities avoid costly mandates.

But the county must sign off on the project.

The DuPage River Salt Creek Workgroup is expected to submit a formal request to the county board later this year. In the meantime, officials are working to design the modification so it wouldn't prevent the dam from doing its job - providing flood control.

"The dam would fully function as it is now," said Stephen McCracken, the group's project manager. "It would just mean that under ordinary flow conditions, the fish species that we're missing would be able to swim through it."

There was a time when pollution wiped out many of the fish species in the river. But since the federal Clean Water Act of 1972, better sewage treatment has dramatically improved water quality.

Combined with recent improvements, the West Branch of the DuPage River has ecosystems where fish can thrive. Still, Flathead catfish, white perch, rock bass and other species are missing north of the dam.

"It's kind of like building blocks of luxury flats," McCracken said. "But the people can't move into them because the gate is locked."

Fawell Dam was constructed by the Illinois Department of Natural Resources between 1969 and 1971. DuPage acquired it in 1998.

While the dam has three box culverts that normally are open, most fish can't pass through them because they have steep slopes.

The plan calls for lowering the floor of one or two of the culverts. Fish then would be able to pass through the channels when the water flow is reduced.

Helping the fish could save money for DuPage's wastewater treatment plants - and the taxpayers they serve.

That's because the state monitors compliance with the Clean Water Act by doing surveys of water quality and aquatic life. If rivers aren't meeting water quality goals, the state can impose additional requirements on the local wastewater treatment plants.

In 2014, new restrictions were placed on DuPage's wastewater treatment plants that could end up costing taxpayers $64 million over the next decade, officials estimate.

Many of the costly mandates could be avoided if DuPage's wastewater treatment plants fund projects that improve local waterways.

Officials, meanwhile, are convinced that modifying Fawell Dam would increase the diversity of fish species upstream.

"In order hit the Clean Water Act goals, we're going to have to modify that structure at some point," McCracken said. "There's just no way we're going to hit the biological goals for the waterway without modifying that structure."

If the county allows work at the dam, the project still would need approval from the Illinois Department of Natural Resources. The soonest construction could begin is 2018 or 2019.