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This outfall pipe, which services downtown Missoula's storm drains, discharges runoff into the Clark Fork River just downstream from Brennan's Wave. Recent water samples taken from the runoff contain concentrations of fecal coliform bacteria "too numerous to count," plus cigarette butts, lead, copper, nitrogen and phosphorous.

With the band strumming out a bass-heavy tune in Caras Park during Out to Lunch on Wednesday, Ben Fitch stood on the rocks at Brennan’s Wave, watching surfers skim the water as his children splashed in the shallows.

As the band played, Missoula’s web of downtown storm drains worked like a network of streams, collecting runoff from the city’s parking lots, streets and alleys. The runoff is diverted here to Caras Park, where it’s discharged through an inconspicuous outfall pipe into the Clark Fork River, just 20 feet away from Fitch and his frolicking children.

What that runoff carries may prove unsettling to the thousands of floaters, kayakers, swimmers and surfers who partake in this popular swimming hole, one that has helped place Missoula among the nation’s top outdoor towns.

“Seems with all the environmentally conscious folks in Missoula, we can come up with a better system,” Fitch said, considering the pipe and its discharge for the first time. “The dirtier this river gets, the less people are going to want to be around it.”

Peter Nielsen, supervisor of the Missoula County Water Quality District, knows what most Missoula residents and visitors do not. A water sample taken from the pipe developed cultures of fecal coliform bacteria “too numerous to count.”

Cigarette butts, trash, lead, copper, nitrogen and phosphorus add to the mix of pollutants washed from the city with each rain and snowmelt. The results are bad for the river, not to mention the health of those who swim near the pipe.

“Most of the downtown is an impervious surface,” said Nielsen. “Whenever someone dumps something in an alley or street, or whenever we have a spill or an auto accident that leaks fluids, the materials reach the river in minutes whenever it rains, and it’s totally untreated.”

Given the implications to human health and water quality, the city is collecting funds from numerous sources to install a hydrodynamic separator above the pipe and intercept the sediment and pollutants before they reach the river.

While the city has installed such devices at other locations where similar pipes discharge into the river, the project at Caras Park marks the highest-impact effort yet undertaken by the city to protect the river.

“It was our highest-priority area,” Nielsen said. “Our monitoring indicates high levels of contaminants that exceed guidelines put forth by the Montana Department of Environmental Quality. This is an effort to try and help clean that up.”


The drainage system below Caras Park directs runoff collected from nearly 63 acres in downtown Missoula to the river.

The flow comes from parking garages, gas stations, gutters and alleyways. The system was developed nearly a century ago, and the city has limited information on the drainage network and its capacity.

What is known is that the outfall pipe drains its dirty concoction into a popular section of the Clark Fork River. Located just below the viewing platform at Caras Park, the area is heavily used by surfers and kayakers. Children often swim near the pipe in the summer, unaware of its contents, and floaters unknowingly trudge through the discharge and the tendrils of green algae that grow nearby.

“We feel this project has a lot of benefits – improving water quality and public heath, and protecting the resources that attract visitors to the area,” said Nielsen. “There’s no community in Montana that has done more to protect its water quality than Missoula. But this is one area where we still have some work to do.”

The Caras Park Stormwater Project includes two phases, beginning with the installation of the separator. Nielsen said the first phase will cost roughly $196,000 to complete, and it could begin early next year.

The city received $125,000 from the Montana Renewable Resource Grant during the 2015 Legislature. Citing the project’s need, the Missoula Redevelopment Agency also approved $25,000 at its last board meeting.

Nielsen said the Water Quality District and the Missoula Parking Commission will likely give an additional $25,000 each to get the project designed and built.

“The separator doesn’t require any outside power,” said Nielsen. “They’re operated on the power of the water itself, creating centrifugal force in the chamber. It allows the solids and heavy material to settle out at the bottom. The floatable materials – the oil and grease – separate out at the top.”

The project’s second phase would remove the separated materials from the device. But that portion of the project is still years away and will require separate funding.

Until then, Nielsen said, the materials will be vacuumed from the new separator by city employees.

“The second phase would infiltrate the discharge to the soil and remove additional contaminants, and eliminate the discharge to the river at all but very high flows,” Nielsen said. “It would mitigate the impact the urban downtown area has in raising water temperatures in the river.”

On Wednesday, as the surfers left the water and the band put away its guitars, Marty Wasserberg watched his grandchildren play from the viewing platform. The Floridian last visited Missoula nine years ago, before Brennan’s Wave opened and the swimming hole below the park became a popular summer attraction.

Wasserberg was also surprised to learn of the pipe’s contents.

“I understand the kids swim over there in the summer,” he said looking downriver toward the pipe and its steady outflow. “This is a fantastic community asset. Where are you going to find this anywhere else? Is it worth protecting? Absolutely, 1,000 percent.”

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