News » Citydesk

City, State Leaders Applaud New System to Solve the Boise River's Phosphorous Problem

by

- Guests at the Dixie Drain commemoration stood on an observation deck to watch treated water from the Dixie Drain flow back into the Boise River. -  - HARRISON BERRY
  • Harrison Berry
  • Guests at the Dixie Drain commemoration stood on an observation deck to watch treated water from the Dixie Drain flow back into the Boise River.


Above the Dixie Drain, the Boise River runs dark brown, loaded with sediment and spiked with phosphorous. But after being sifted through the new facility, it courses almost clear past an observation deck where the newly treated water flows back to its source.

Boise and Idaho state leaders gathered among the cornfields northwest of Caldwell this morning to christen the Dixie Drain, the city's new $21 million phosphorous filtration facility.

"This shows government agencies can work together," said Boise Mayor Dave Bieter at the Aug. 24 commemoration ceremony. "That's just what citizens of all ideologies are looking for."

The Dixie Drain is Treasure Valley cities' answer to EPA guidelines that limit the Boise River's phosphorous load. Those cities, along with Idaho's congressional delegation, the Environmental Protection Agency, Idaho Department of Environmental Quality and conservation groups, devised the drain as a cost-effective way to drastically reduce the amount of phosphorous reaching the Snake River.

The problem is severe. Untreated, the Boise River contains approximately 4,000 micrograms of phosphorous per liter—vastly higher than EPA limits, which say the river should contain no more than 70 micrograms of phosphorous per liter between the months of May and September.

Since agriculture activities contribute significantly to the amount of phosphorous in the Boise River—but are exempt from regulation by the Clean Water Act—cities must foot the bill for the Dixie Drain, which was built deep in Canyon County to capture both agricultural and urban pollutants.

- The Dixie Drain bonds polyaluminum chloride to phosphorous in the Boise River to physically separate it from the river water. -  - HARRISON BERRY
  • Harrison Berry
  • The Dixie Drain bonds polyaluminum chloride to phosphorous in the Boise River to physically separate it from the river water.
The stakeholders in attendance—which included at least five mayors, representatives of the EPA and IDEQ, and Rep. Mike Simpson and Sen. Mike Crapo—hailed the Dixie Drain as an engineering marvel resulting from cooperation among local government officials and environmental agencies.

"The EPA gave us the flexibility to come up with an alternative," said Simpson. "That's what we expect government to do."

"The flexibility has generated something I believe could be a national model," Crapo said.

"This is a treasure for Idaho ... and projects like this will bring [the Boise River] back," said EPA Region 10 Administrator Dennis McLerran.

- Boise Mayor Dave Bieter commemorated the Dixie Drain, hailing it as a landmark in cooperation among stakeholders. -  - HARRISON BERRY
  • Harrison Berry
  • Boise Mayor Dave Bieter commemorated the Dixie Drain, hailing it as a landmark in cooperation among stakeholders.
The Dixie Drain diverts river water into the multi-phase treatment facility, which sifts out sediment and uses polyaluminum chloride as a bonding agent to pull phosphorous from the water. The process is expected to remove up to 8,000 tons of sediment and 10 tons of phosphorous from the river each year.

According to Public Works engineer John Tensen, it removes 1.5 pounds of phosphorous from the river for every pound of phosphorous untreated at Boise's water treatment plants, saving cities along the river millions of dollars.

"On a pound-for-pound basis, there's just no comparison," he said.