Navigating water quality in Lake Pend Oreille

By Karissa Huntsman
Reader Contributor

As snow is falling on the mountains and hills around Sandpoint, many are looking ahead to the upcoming winter season. Here at the Idaho Conservation League, we are still reflecting on the summer months and Lake Pend Oreille. 

Each year from May through September, we conduct our Water Quality Monitoring Program — a citizen science initiative dedicated to protecting Lake Pend Oreille and the Pend Oreille River. Our amazing volunteers, otherwise known as water quality stewards, collect data and water samples monthly to build a solid understanding of the condition of local waterways. 

This summer we added four new sampling stations at Camp Bay, Kootenai Bay, Oden Bay and Sand Creek, bringing us to a total of 15 stations. Each station is selected through close collaboration with the Idaho Department of Environmental Quality (DEQ), which uses our data to make management decisions that protect water quality. 

Courtesy photo.

With increasing shoreline development, our goal is to establish an understanding of baseline conditions, so issues can be detected early before water quality is compromised. Each sample collected throughout the summer was tested for various water quality indicators like temperature, dissolved oxygen, total nitrogen, total phosphorus, and E. coli, to name a few. 

Based on this season’s monitoring, water quality in Lake Pend Oreille remains fair — meaning it’s not terrible, but there is room for improvement. 

To provide some context, in 2002, a cleanup plan called a total maximum daily load (TMDL) was created for the area near the shoreline of Lake Pend Oreille, due to increasing growth of algae and aquatic plants. The issues were found to be the result of excess total phosphorus (TP), leading to a TMDL stating that nine micrograms per liter (µg/L) of phosphorus is the maximum amount the water can assimilate while still meeting water quality standards. 

Across 14 of the 15 stations we monitor, TP ranged from a minimum of two µg/L to a maximum of 52 µg/L, with an average of 13 µg/L, so not too far from the target. 

Total nitrogen (TN) at these 14 stations ranged from a minimum of 50 µg/L to a maximum 805 µg/L, with an average of 306 µg/L. High concentrations of both of these nutrients can result from lawn runoff, soil disturbances, septic systems and discharge from sewage treatment plants. 

While water quality is fair in most places, Boyer Slough is an outlier. There, the water quality is poor. Through this summer’s monitoring, we found TP levels in Boyer Slough ranging from 60 to 2,930 µg/L, with an average of 740 µg/L. TN levels ranged from 540 to 17,700 µg/L, with an average of 4,416 µg/L. That’s more than 56 times the average for TP at the other stations, and more than 14 times the average for TN. 

These numbers create an environment that is conducive for invasive weeds and toxic algae blooms, like the one that occurred in the slough in 2021.

You may be wondering, what is going on in Boyer Slough? The nearby Kootenai Ponderay Sewer District discharges wastewater into Boyer Slough from approximately October to May each year, though sometimes well into summer, depending on conditions. During the summer months, after water saturation of the soil has decreased, the discharge is moved to a land application site, where the wastewater is used to water trees. The trees uptake the nutrients and utilize them for their growth. However, water quality problems remain in the slough throughout the summer. 

Despite the pollution in Boyer Slough being a problem for many years, there are reasons to be hopeful about its recovery. The Kootenai Ponderay Sewer District has successfully acquired funding to upgrade its treatment facility, and is working on its plan. DEQ has convened a watershed advisory group of local stakeholders to develop a cleanup plan that will ensure the long-term health of Boyer Slough. The data collected by our water quality stewards will inform this plan.

It will take some time to implement the treatment plant upgrades and allow for the slough to recover from decades of nutrient overload, but the wheels are turning in the right direction. Engaged community members can make all the difference by showing up, holding decision makers accountable, educating each other and getting involved in citizen science. 

When I asked first-year steward Deborah Crain about her experience this summer, she said, “It gives a feeling of hope, to be out there with so many others doing something proactive to protect the lake.” 

This is a message that I have heard time and time again from our volunteers. As Lake Pend Oreille remains the lifeblood of our community, linking us through invaluable resources, from recreation to drinking water, it instills a collective responsibility to learn about and care for it. Using the information we gather through this program, we hope to empower the community to engage in meaningful ways, when it really matters. 

To see results from this year’s monitoring and to learn more about the program, visit idahocl.org/WQMP. If you are interested in becoming a steward next summer, email [email protected]. 

We look forward to continuing to work with volunteers and community members to protect the iconic lakes, rivers, and waterways of North Idaho. Just as these waters are the lifeblood of our ecosystems and communities, the people who speak up for them are our heartbeat. 

Karissa Huntsman is community engagement assistant for the Idaho Conservation League.