A look at land use, lake use in Coeur d’Alene

Catie Clark//March 29, 2021

A look at land use, lake use in Coeur d’Alene

Catie Clark//March 29, 2021

Lake Coeur d'Alene shoreline at Tubbs Hill Park.
Lake Coeur d’Alene shoreline at Tubbs Hill Park. Photo by Jason Patrick Schuller, CC0 via Wikimedia Commons

Third in a six-part series.

Chris Filios is a Kootenai County Commissioner. He’s a Republican, a past member of the National Guard, an appraiser and realtor and an elected official on-record for avoiding foregone taxes. This is not the sort of record that paints him in environmental activist colors.

That is why his quote that “this community will live or die by the health of Lake Coeur d’Alene,” is startling.

However, Filios and his commissioner colleagues appreciate the economic contribution of tourism to the county, which is why the county is a sponsor of an ongoing study by the National Academy of Sciences. Kootenai’s reliance on tourism is underscored by its disproportionately-higher unemployment rates in the hospitality sector during the pandemic. Protecting the tourism sector is a matter of economic survival.

No one wants to visit a sick lake. Research backs that up: a 2009 economic study published by the American Chemical Society identified the main casualties attributable to lake eutrophication as losses in lakeside property values and recreation-use revenues. Losses were estimated as billions every year nationally.

Run-away eutrophication is what the lake risks. Eutrophication is where a body of water becomes progressively enriched with minerals, nutrients and biomass. The most visible symptom is the proliferation are algal blooms. Another symptom is the decline of the local fishery. For waters undisturbed by development, eutrophication is usually very slow; but with development, the result can be as bad as the blighting of Lake Erie.

“Lake Coeur d’Alene is not one big box,” explained Craig Cooper, the lake’s limnologist at the Idaho Department of Environmental Quality. Cooper outlined the water cycle of the lake, with differences between the deep cold north and shallow warm south ends of the lake and how runoff changes by location, land use and time of the year. The cycle is complex, but one constant emerged: human land use changed the nature of runoff and groundwater infiltration into the lake. How badly and quickly it will affect the lake is the unknown that the NAS study aims to address.

Sediments swirls in Lake Coeur d'Alene during 2008 flooding at the mouth of the Coeur d'Alene River.
Sediments swirls in Lake Coeur d’Alene during 2008 flooding, looking east toward the mouth of the Coeur d’Alene River. Photo courtesy of the EPA

Cooper outlined effects already known to affect other lakes: “When you clear the land and remove riparian buffers, more water runs off directly into the lake and less filters through the soil into groundwater.” With development, more sediment and nutrients wash into the lake: “Between 60% to 80% of the nutrients that get into the lake, stay in the lake,” Cooper related. They are mostly phosphorus-based with some added nitrogen, originating from sources such as chemical fertilizers, urban storm water and septic tanks.

Because increasing nutrients affect oxygen in the lake, they can lead to algal blooms, already observed in warmer southern end of the lake. They may lead to changes in oxygen, which could liberate metals in mine wastes at the bottom of the lake. Changes are already measurable. According to IDEQ, one key metric is phosphorus, which regulates many of the processes that influence oxygen. Phosphorous levels have recently been increasing by about 2% per year on average, though these can fluctuate significantly from year to year.

David Callahan, director of community development for Kootenai County, provided numbers on development: “Most of the lakeshore (73%) in the unincorporated county is developed. There’s not a lot of undeveloped land left.” Added to this, the lakeshore allows “the highest land density in the zoning ordinance, approximately five houses per acre.” Of the 122 miles of shoreline, 91% of it in in unincorporated Kootenai County.

The county also has a 25-foot buffer zone requirement between the lakeshore and any human uses. Despite relatively lax buffer requirements, the Coeur d’Alene Lakeshore Property Owners Association attempted to eliminate it altogether in 2015. “Even Bonner County is more stringent than we are,” remarked Filios. “Their buffer is 40 feet.” Buffers on federal lands in Montana start at 50 feet; in some counties, they can be up to 300 feet. Minnesota’s buffer law mandates 50 feet and South Dakota incentivizes buffers with tax breaks.

Previous articles in this series stated that higher oxygen levels at the lake bottom would release metals from the mine wastes. Conditions between oxygen and minerals for metals release are more complex than this; previous articles now reflect this clarification. The statement about measurable water quality metrics for the lake was clarified at the request of IDEQ.