Fish and recreationists alike may be pleased by city project in West Spokane

Apr. 24—The Cochran Basin is the last stop before urban pollutants like vehicle fluids and landscaping chemicals enter the Spokane River from about 5,000 acres on the north side of town.

The area is the city's largest stormwater basin and is visited by recreationists who hike, golf, disc golf or kayak.

But the stormwater often carries chemicals via roads or pipes that, if left unfiltered, harm waterways.

This was the case in western Spokane, where the city found low oxygen levels in water downriver of the TJ Meenach Bridge.

Near the Downriver Golf Course, the city began work in 2019 on a series of projects to properly treat stormwater before it enters the river.

While they tore up the area to implement the project, they also made some snazzy upgrades.

"We thought, 'If we're going to tear everything up, we might as well make it better above ground too,' " said Kirstin Davis, communications manager for the city of Spokane.

City officials held an event Wednesday to announce the completion of Downriver Park, a boat launch area for nonmotorized watercraft. It includes a paved parking lot, walking trails, restrooms and landscaping.

"There used to be a tiny little old parking lot with a couple picnic benches," said Garrett Jones, interim city administrator. "You couldn't turn around in here with the trailers, and getting out was a mess, so this has been a huge improvement."

But the most vital aspect of the Downriver Park is what's underground.

Pipes and roadways bring untreated stormwater from around North Spokane to an area in the middle of the circular parking lot — currently, it looks like an empty pool.

"It comes to this area," Jones said as he pointed at the new parking lot. "And it will settle here to filter out all the contaminants — naturally."

The ponds will include stone, fabric filters and special "bioretention soil," which is engineered to treat stormwater, according to project plans.

According to city documents, the ponds are capable of holding some 11 million gallons of water.

Before the man-made ponds, the basin had less capacity to hold stormwater, thus was susceptible to overflowing. Water that didn't seeping into the soil was "ultimately discharged untreated into the Spokane River through an outfall located at the southwest corner of the basin near the TJ Meenach Drive Bridge," according to city records.

The untreated water resulted in the impairment of the Spokane River, meaning it contained low oxygen levels, downstream of the Cochran Basin outfall, including in Long Lake.

"This is directly caused by the introduction of the pollutants that are carried in the stormwater runoff," according to the city findings.

Recent city efforts to heal the Spokane River included the implementation of large pipes to bring water to the filtration ponds — most notably, a 36-inch pipe under the Downriver Golf Course.

It connects an existing pipe at the intersection of Cleveland Avenue and Riverview Drive to the Downriver Disc Golf Course filtration ponds.

While underground, the city used it as an opportunity to update the course's irrigation system.

"We were able to upgrade that entire irrigation system and save 11 million gallons of water a year just on those upgrades," Jones said. "The new automated system creates a lot more efficiency."

And disc golfers are also teed-up for upgrades.

The city consulted a designer for a new 18-hole course that will use the new filtration ponds as hazards.

The course will feature a paved parking lot, cement tee-pads and will also receive updates to its irrigation system, which will make all the difference, Jones said.

"It's amazing what irrigation can do with the health of the turf," he said.

Though Downriver Park is ready for recreation, the disc golf course is not, despite construction being completed, Jones said.

"I know our users are champing at the bit," he said. "But we want to be sensitive to the grasses and native plants to give them a chance before everyone starts tromping through there."

Davis said the city is planning to open the course in June and teased that the city may host an inaugural tournament to celebrate its opening.

In conjunction with the basin project, the city has completed construction on the Cochran Control Facility Project. At the southeast corner of the TJ Meenach bridge, infrastructure that city workers often call "the brain" of the Cochran Basin, kicks in during storms when the ponds risk being overfilled.

If it needs, the control system would allow entry of stormwater to a series of tanks in the area, according to Davis.

The tank system has been in place for two years, but the control vault will begin to get used this summer, she said.

"Everything is there," Davis said. "We expect to take it for a drive in July or August."

After final touches are made on the series of stormwater projects at the Cochran Basin, the city will have invested over $15 million of state and local funds, which Davis said were well-spent.

"When departments collaborate for a project like this, one that limits pollutants and is combined with recreation areas, it maximizes public funds," she said. "It makes so much sense."