Five years ago, officials from the Coeur d’Alene Tribe and the state of Idaho shook hands on a deal to address historic mining pollution at the bottom of Lake Coeur d’Alene.
Local leaders were sensitive about the potential stigma of a Superfund cleanup on Coeur d’Alene’s resort town image. Tribal officials agreed that other measures to protect the lake’s water quality were an acceptable alternative.
But Tuesday, tribal officials said not enough is being done to protect the lake from excess nutrients that increase the risk of heavy metals becoming suspended in the water.
“Imagine our lake having algae blooms where it’s not safe for kids to swim. We have to be proactive. We can’t wait for that to occur,” said Phillip Cernera, director of the Coeur d’Alene Tribe’s lake department.
Several hundred people attended a Tuesday conference on Lake Coeur d’Alene put on by the tribe, the University of Idaho and the Idaho Department of Environmental Quality.
The lake is an asset that drives North Idaho’s economy and contributes to local residents’ quality of life, but action is needed now to protect the lake’s water quality, speakers said.
More than 75 million tons of lake sediments are polluted with lead, arsenic, cadmium and zinc that washed downstream and into its waters during a century of mining in Idaho’s Silver Valley.
When the lake water has high oxygen levels, it keeps the metals in the mud at the bottom of the lake, scientists said. But when Lake Coeur d’Alene’s water chemistry is disrupted, the metals can start to move.
Nutrients, such as phosphorus, disrupt the balance by causing excess aquatic plant growth. When the plants decompose, oxygen levels in the water plummet.
During the past three years, water samples taken at the Tubbs Hill recreational area show decreased oxygen levels and higher levels of dissolved lead.
“We’re only just beginning to see the impacts. There is still time to respond,” said Craig Cooper, a lake scientist for the Idaho DEQ.
But scientists are paying attention to the small changes in the water quality as early warnings of where the lake is headed, he said.
In 2013, low oxygen levels in the Coeur d’Alene River resulted in high releases of lead, arsenic and zinc from the river’s sediments, said Dale Chess, the tribe’s lake scientist.
“This is something we don’t want in Lake Coeur d’Alene,” he said.
During the past five years, local communities have worked to reduce the amount of phosphorus flowing into the lake, said Laura Laumatia, the tribe’s lake management plan coordinator.
The city of Plummer upgraded its sewage treatment plant and several lakeshore communities switched from septic systems to sewer treatment. Projects to control lakeshore erosion and stormwater runoff also help keep nutrients out of the lake.
The next step is a comprehensive study of how phosphorus and other nutrients get into the lake, Laumatia said. That will help policymakers set priorities for taking action.
But funding for future work is scarce, said Cernera, the tribe’s lake director.
Each year, the tribe and Idaho DEQ jointly spend about $1 million on water-quality monitoring in the lake and public outreach. Some of the actions needed to reduce nutrient loads, such as hooking up lakeside communities to sewers, have price tags in the tens of millions of dollars, he said.
“We don’t have the money to fully implement the plan,” he said.
But community residents put a high value on the lake, which can help drive long-term changes to protect water quality, said Charles Buck, the University of Idaho’s executive officer in Coeur d’Alene.
In a recent study, more than half of Coeur d’Alene residents surveyed listed their city’s scenic beauty as its top asset.
“It illustrates a remarkable agreement on the value of the lake,” Buck said. “When we reach agreement, that’s when progress occurs.”