Hayden Lake, a favorite cold water fishery that is nestled into the Coeur d’Alene National Forest, has begun to show the effects of abuse to its watershed. Hayden Lake is unique in that it is a bowl that has no outlet streams, thus what flows into Hayden Lake, stays in Hayden Lake- allowing pollutants to concentrate as fresh water evaporates.

As with many of the lakes in this region, the pollutant of concern is phosphorus. High phosphorus levels yield algae blooms (sometimes toxic) and fertilize invasive aquatic plants in the lake (Eurasian Milfoil).  Algae blooms are one of the more visible consequences of dissolved oxygen levels decreasing, phosphorus levels increasing and water temperatures increasing- this trifecta is what threatens the habitat that cold water aquatic life requires to survive, most notably the westslope cutthroat trout- a true prize for anglers at Hayden Lake and north Idaho.

In 2011, Kootenai Environmental Alliance began piloting a biomimickry technology, floating treatment wetlands, on Hayden Lake to address the recycling phosphorus pump perpetuated by the birth/death cycle of aquatic plants and by activities that churn up the lake bottom.
The floating wetland mats create a concentrated wetland effect by utilizing a buoyant matrix mat (made from extruded recycled plastic bottles) with natural vegetation planted on top to mimic what occurs naturally in healthy wetlands. Plants grow hydroponically allowing the roots to utilize nutrients in the water.

Jim Ekins with University of Idaho and North Idaho College INBRE students planting a floating wetland with water sedges, rushes and monkey flowers.

Ultimately, the floating treatment wetland produces a concentrated and sustained wetland effect, where the benefits of every 250sq ft of island equal the ongoing benefits of a full acre of natural wetland surface area, with those benefits sited precisely where the lake and its fishery need them the most.” says Karen Hayes, Kootenai Environmental Alliance project volunteer.

Addressing the primary sources of phosphorus pollution, like logging, advanced development in the watershed, stormwater runoff and erosion is necessary to significantly improve the water quality in Hayden Lake, but that is a long road with little funding. Our goal is to find ways to reduce excess nutrients in the lake’s bays now, which could decrease the prevalence of algae blooms and provide swimmable, fishable, drinkable water.” Adrienne Cronebaugh, Executive Director for Kootenai Environmental Alliance.

This summer, Kootenai Environmental Alliance, Idaho Department of Environmental Quality, the University of Idaho and North Idaho College INBRE is working cooperatively with the Hayden Area Regional Sewer Board on a Supplemental Environmental Project (SEP) as part of an Amended Consent Decree with the Idaho Department of Environmental Quality. As part of the project Kootenai Environmental Alliance will launch a total of eight floating treatment wetlands into four bays around Hayden Lake for monitoring and research.

The floating wetland technology has been shown to remove nutrients (specifically phosphorus), decrease biological oxygen demand, and reduce total suspended solids in wastewater treatment environments. Over the course of the 2015 summer season, the University of Idaho and North Idaho College INBRE students will be monitoring to see the floating wetlands effect on water quality in a lower productivity environment, like Hayden Lake, and determine how much phosphorus the plants are responsible for in the uptake.” Kristin Larson, Idaho Department of Environmental Quality.

This project was undertaken in connection with the settlement of an enforcement action taken by the Idaho Department of Environmental Quality for violations of Land Application Permit No LA-000109-03.