The largest floods in the history of the world started roaring through Spokane County some 18,000 years ago.
They burst through the ice dam holding in Glacial Lake Missoula 40 or so times over 3,000 years. The biggest was 10 times bigger than all the Earth’s rivers combined. Waters snapped trees like toothpicks, stripped away soil and gouged lakes and canyons out of the volcanic bedrock.
It’s been 15,000 years since a cataclysmic flood tore up Spokane County. In most places, topsoil has returned, covering up the scars left by the raging waters. And yet, the West Plains’ water troubles remain, thanks to the legacy of the Missoula floods.
Solid basalt lies beneath the region’s thin layer of topsoil. The land drains badly because water has few places to go. Flooding is an annual expectation, especially in spring when rains fall, snow melts and the ground is still frozen.
Water has throttled new construction and growth, even though the area’s conveniently located along an interstate, next to an airport and by a railroad. If only the floods could be controlled, government officials lament, the region could be fully developed.
A public development authority is hoping a $150 million stormwater infrastructure project can handle the water and unlock the West Plains’ full economic potential.
S3R3 Solutions, the public development authority that uses Spokane and county tax revenue to recruit businesses to the West Plains, has spent nearly four years working on a stormwater study.
That study analyzed and modeled stormwater conditions within S3R3’s territory, a 15-square-mile area of Spokane and unincorporated county surrounding the Spokane International Airport.
With the study complete, S3R3 has a plan for solving the stormwater problem.
Pipes would carry water to filtration sites. Those sites would sit atop paleochannels, permeable subterranean passageways amid the impenetrable basalt. Water would trickle into the channels and flow away harmlessly toward the Spokane River.
Todd Coleman, S3R3’s executive director, said the conveyance network would free up more land for industrial development. That in turn would create jobs, grow the West Plains’ economy and generate tax revenue.
Spokane County and Spokane elected officials have voiced support for the proposal. County Engineer Matt Zarecor said the stormwater project would be wise, long-term planning.
“It’s a great idea,” Zarecor said in an April 18 Spokane County Commission meeting. “It’s going to benefit everybody.”
How would it work?
Spokane County has been talking about solving its stormwater woes for decades.
The county hired engineering consultants more than 20 years ago and told them to devise a solution. The general concept has already been done, too – the airport uses a paleochannel to handle its stormwater.
But until now, governments haven’t acted on the ideas dreamed up 20 years ago.
Here’s how S3R3’s plan would work.
Imagine a rainstorm dumps buckets of water on the West Plains.
Much of that water bounces off rooftops and asphalt, following the path of least resistance and puddling when it runs into a dead end.
New stormwater infrastructure would funnel the water into roadside swales. Plants would line those shallow ditches and begin the filtration process, sucking up water, heavy metals and other pollutants.
Whatever water the plants don’t absorb will run into pipes. Those pipes will use gravity to route water to five stormwater management facilities.
One of those facilities by the northeast portion of the S3R3 boundary would be a standard detention system, in which water is stored and allowed to percolate into the ground.
The other four would be filtration systems, full of man-made filters. Once the water passed through the filters it would enter a paleochannel and continue on to the Spokane River.
Coleman said the stormwater project would accomplish three goals.
First, it would reduce chronic flooding.
Second, it would help the airport.
West Plains developers currently rely on evaporation ponds to handle stormwater. It’s a crude, expensive and occasionally ineffective method. It makes the airport a bit nervous.
For airports, standing water is a potential threat because ponds can be magnets for waterfowl. Ducks and planes don’t mix.
Wildlife collisions can bring down aircraft and have killed hundreds of people in the past 30 years. The Federal Aviation Administration requires airports to minimize nearby wildlife habitat. A regional stormwater system that reduces the need for evaporation ponds would be a win for air safety.
Third, the stormwater system could be a boon for economic development.
Evaporation ponds take up a lot of space, sometimes 30% of the land a developer needs for a given project. That costs businesses money and can dissuade them from coming to the West Plains.
“You have to do some pretty sophisticated things to deal with the stormwater,” said Breean Beggs, Spokane City Council president and a member of S3R3’s board.
Developers would save money if they could tap into a regional system instead of designing their own.
“If a developer were able to reduce the land they need to support the building and parking, and then pipe into a system that was available to them, then they would pay a premium for that service,” Spokane County Commissioner Al French said.
A regional system would also free up more land.
Coleman said the stormwater infrastructure could effectively increase the number of businesses in the area simply because there’d be more physical room to build.
Who’s going to pay for it?
A handful of stakeholders would share the $150 million cost.
According to Osborn Consulting, the company that completed S3R3’s study, state and federal grants could cover $62 million.
Developers would directly contribute $20 million. S3R3 would pay $15 million. Spokane and Spokane County would pay $13 million each. Stormwater utility taxes would make up the difference.
Those numbers are just preliminary estimates, Coleman emphasized. French and Beggs both stressed that they believe the cost of the system should fall primarily to developers.
Coleman said he understands $150 million is a big number for stormwater infrastructure. But the economics are sound, he said.
S3R3’s consultant calculated that for every dollar invested, the region would get $3.19 back. The $150 million project might generate a nearly $500 million return. It’d bring in more businesses, create more jobs and create more tax revenue for Spokane, Spokane County and S3R3.
If the stormwater project happens, it’ll happen piece by piece. The vast network of swales, conveyance pipes and filtration sites might be gradually built over the next 20 or so years.
“We don’t have to bite the apple on all of them at once,” French said.
But the project could begin soon. Spokane and Spokane County can start adding the swales and pipes as they build new roads and repair old ones.
Coleman said S3R3 needs to do more planning and studying before the project’s ready for implementation. The paleochannels need to be studied, to make sure they flow to the Spokane River as expected. The funding strategy needs more analysis.
But the West Plains is already the fastest growing industrial area in Washington, Coleman said. As more industrial development breaks ground there, the need for a regional system will increase.
“We’ve just got to get moving,” Coleman said. “We’ve just got to start and we’ve got to keep pushing forward on it.”