Phosphate Could Stir Up Lake Cda Pollution Conditions Caused By Chemical Overload Could Pull Toxic Metals From Mine Tailings, Sending Them Downstream

(From April 8, 2000 article, “St. Joe helps balance phosphate levels”) Phosphate levels have doubled during the last decade in the Coeur d’Alene River, but not in Lake Coeur d’Alene. Phosphate level increases in the lake were incorrectly reported in The Spokesman-Review on Thursday.

Lake Coeur d’Alene faces a threat that could free millions of tons of mine pollution on the lake bottom, a federal scientist says.

Phosphate, a chemical found in everything from fertilizers to detergents, triggers uncontrolled algae and plant blooms that suck oxygen from water and warm it.

In Lake Coeur d’Alene, changes caused by phosphate overload could pull lead and other toxic metals from up to 75 million tons of mine tailings in lake mud, scientists say.

A U.S. Geological Survey report unveiled this week shows that phosphate is flowing into the lake at an alarming rate. Researchers say they don’t know if the marked increase over the past decade is an aberration or a more serious warning sign.

“To me, it’s a wake-up call,” said Paul Woods, a Boise-based USGS researcher.

Keeping phosphates down was a priority in a sweeping 1995 plan to safeguard the lake.

“This isn’t the trend the lake-management plan wants to see,” Woods said.

The amount of phosphates flowing into Lake Coeur d’Alene more than doubled between 1991 and 1999 from 49,000 to 107,000 pounds a year, according to the USGS report. In comparison, phosphates in the St. Joe River dropped from 160,000 pounds to 62,000 pounds.

The new findings could put a damper on a mine waste cleanup tool that’s cheaper than digging out pollution: treating mine waste with phosphates or phosphoric acid to trap metals on site via chemical reaction.

Frank Frutchey, a Rose Lake rancher pushing cleanup with a combination of phosphates and vegetative cover, pointed out that Coeur d’Alene River concentrations of the stuff are dwarfed by amounts dumped down-river.

The city of Spokane releases 700,000 pounds a year of phosphorus into the Spokane River, according to the USGS study. The city in 1990 ordered a ban on detergents containing phosphates.

“We’ve been very sensitive to phosphorus in the last 10 years,” said John Roland, with the Washington Department of Ecology.

Possible sources of the phosphate rise in the Coeur d’Alene system include shorebank erosion and more homes along the reaches of the Coeur d’Alene.

Another potential source is poor erosion controls at reclamation projects cleaning up old Silver Valley mines, USGS officials said.

Over the past decade, a myriad of groups have worked to stem lead and other metals flowing from historic mines: mining companies, the Silver Valley Natural Resources Trustees, the Bureau of Land Management and the U.S. Forest Service.

Trustees project coordinator Marti Calabretta defended the work, which she said involved daily water turbidity tests and 13 miles of bank stabilization, all under state oversight.

Calabretta said cleaning up mine waste - zinc in particular - can increase phosphate releases because zinc keeps phosphates from washing downstream.

“You do one thing, and it will aggravate another problem that had been taken care of,” she said.

But Wood and others suggested reclamation projects need more planning to ensure that moving soil doesn’t create problems downstream.

“Before, there was an assumption if you move dirt, you’re just going to clean things up,” said Mike Beckwith, a USGS researcher based in Sandpoint. “This may or may not be true.”

Woods announced his findings Wednesday to the Coeur d’Alene Basin Interagency Group, a regular forum of regional public scientists.

The new data is part of a 2-1/2-inch thick USGS report on 1999 water quality data from Mullan to Lake Roosevelt commissioned by the Environmental Protection Agency.