Spokane-Rathdrum Prairie Aquifer project wraps up

A five-year project to use trees to promote the health of the Spokane-Rathdrum Prairie Aquifer has ended, with new trees planted, a blueprint for where to plant more, a boost for a Hayden program that uses poplar trees to drink up treated wastewater and various efforts to improve forest health throughout the region.

“Knowing how trees could benefit the aquifer, we had a really unique opportunity,” said Mary Fritz, program planning specialist for the Idaho Department of Lands in Coeur d’Alene.

The department secured a $300,000 federal grant, which was matched with local funds from an array of public agencies, companies and private landowners.

A centerpiece of the project was an analysis of the tree canopy in Kootenai County, where cities and towns were found lacking: Trees cover just 14 percent of Coeur d’Alene, 7 percent of Hayden, and 6 percent of Rathdrum and Post Falls. The cities want to increase that to 30 percent.

Spokane, by contrast, is nearly 22 percent covered with trees.

Now, cities in Kootenai County have a database showing where more trees are needed, for everything from shade and energy savings to filtering out water and air pollutants, and reducing runoff and erosion.

Hayden saw one of the most dramatic impacts; there, the regional sewer district uses a plantation of poplar trees to slurp up its treated wastewater during the summer months. But an infestation of sawflies was ravaging the trees, Hayden Area Regional Sewer Board Director Ken Windram said.

The Department of Lands helped the district eradicate the pest and plan for ongoing control efforts.

The sewer district uses the fast-growing poplar trees plus about 250 acres of alfalfa to drink up its wastewater in the summer months, when the Spokane River drops below 1,000 cubic feet per second at the Post Falls Dam and it’s no longer safe to discharge the treated water into the river. Because the aquifer – the sole source of drinking water for half a million people in the region – lies below the plantation, the trees’ soil moisture must be constantly monitored to make sure they consume all the water.

The tree project is just a small piece of the region’s efforts to protect the aquifer. Dick Martindale, manager of environmental health for the Panhandle Health District, said extensive efforts to prevent contaminants from getting into the aquifer have paid off.

“After 30-plus years, we can say, ‘Yeah, these programs actually work,’ ” Martindale said. “The water quality was poor back in the ’70s and has actually improved through the ’80s and early ’90s, and now it’s stabilized, even with the massive increase in growth and development that we’ve had. So the good news is that we’re very successful – you can still in Idaho put in a well and pump out safe, clean drinking water without having to treat it, which is kind of remarkable.”