To protect and improve lake water quality by limiting basin-wide nutrient inputs that impair lake water quality conditions, which in turn influence the solubility of mining-related metals contamination contained in lake sediments.


In an effort to address the many issues facing Coeur d’Alene Lake, the Coeur d’Alene Tribe (Tribe) and the State of Idaho Department of Environmental Quality (DEQ), collectively, the Lake Management Team, have collaboratively developed the 2009 Lake Management Plan (2009 LMP) with the goal: to protect and improve lake water quality by limiting basin-wide nutrient inputs that impair lake water quality conditions, which in turn influence the solubility of mining-related metals contamination contained in lake sediments.


The scope of lake management encompasses the entire Coeur d’Alene Lake Basin. The reason for this is practical: loading of the lake with metals, sediments, and nutrients results from human activities around the lake, in upland areas, and along tributary streams and rivers. This scope is essential to effectively address the key influences on water quality. The scope is intended to follow natural boundaries, promote integrated solutions, and maximize the use of available resources to benefit water quality.


The Lake Management Team recognizes the importance of setting priorities to address the challenges posed by the scope and cost of implementing the plan. We have developed a two-tiered approach. Tier I is considered the essential core LMP program for our initial focus:

  1. Increase scientific understanding of water quality trends
  2. Inventory basin-wide nutrient sources to set implementation priorities
  3. Coordinate existing programs with LMP partners
  4. Increase the community’s awareness of lake conditions and promote lake stewardship.

Tier II of the LMP includes nutrient reduction projects, special studies, and coordination with TMDL program implementation. To learn more about the LMP, you can read the entire plan here.

LMP Management Objectives

  1. Improve Scientific Understanding of Lake Conditions
  2. Over the last 30 years, Coeur d’Alene Lake has been the focus of considerable scientific investigation. Though we have increased our understanding of water quality trends, the complex interactions between the physical lake processes, nutrients, phytoplankton production (microscopic algae growth), and heavy metals require more in-depth study to improve our knowledge and the basis for our lake management decisions.

    An ongoing science program, consisting of routine monitoring, special studies, and computer modeling, helps us ensure that our adaptive management approach is effective and efficient. Our program is evaluated annually, and on a five-year basis by the Environmental Protection Agency (EPA). Our water quality monitoring reports are regularly shared with community groups and technical agency partners, so that current information is available to all stakeholders. Data from routine monitoring and special studies are used to improve modeling of lake dynamics and overall understanding of lake conditions.

  3. Establish and Strengthen Partnerships to Maximize Benefits of Actions Under EXISTING Regulatory Frameworks.
  4. The 2009 LMP relies on our agency and community partners to use existing regulatory tools and management actions to address nutrient and sediment inputs to Coeur d’Alene Lake. No new regulations are created by the LMP. The LMP Management Action Tables, or MATs, are a critical feature of this approach (LMP Appendix C). The MATs document the diverse jurisdictions of local, State, Tribal, and Federal agencies, as well as existing programs, BMPs, codes, and regulations that influence water quality. We conduct a regular review of these tables to update progress on achieving LMP goals and explore new opportunities for partnerships.

  5. Develop and Implement a Nutrient Reduction Action Plan.
  6. In 2010, the Lake Management Team began basin-wide nutrient source inventory in order to identify and prioritize actions to reduce nutrient inputs. This inventory focuses on nutrient and sediment contributions at key locations across the basin.

    Our first stage in the inventory has focused on the St. Joe/St. Maries watershed. We collect water samples throughout the year to develop an understanding of nutrient sources throughout the basin, such as failing roads, eroding streambanks or stormwater runoff. We then compare our data to information from other sampling programs, wastewater treatment plants, land-use mapping, and other sources. Our goal is to develop a Geographic Information System (GIS) environmental database layer that clearly depicts nutrient contributions throughout the basin. This information will provide the Tribe, DEQ, and LMP partners with data to support future decisions about where to focus nutrient reduction work.

    We are in the process of analyzing three years-worth of data from the St. Joe/St. Maries watershed to help identify and prioritize potential on-the-ground improvement projects to reduce nutrient inputs. We will move our monitoring efforts to another part of the basin to repeat this process in another inflowing stream.

    Projects & Partnerships
    With good data, we will be able to develop projects with partners and landowners to reduce nutrient loading into the lake. Examples of ongoing programs and projects are: upgrading wastewater treatment facilities, stabilization of eroding river and stream banks, reduction of sediment delivery from state and federal public lands, implementing agricultural Best Management Practices (BMPs), and enforcing land development ordinances.

    We also coordinate with Watershed Advisory Groups that are working to support TMDL Implementation projects. These are incorporated into the LMP nutrient reduction plan.

    Avista/FERC Mitigation Program
    The Coeur d’Alene Tribe and the State of Idaho are parties to the Federal Energy Regulatory Commission’s (FERC’s) relicensing process for the Post Falls Hydro-Electric Dam (HED), owned by Avista Corporation. As part of this process, project operation impacts on natural resources were determined and mitigation measures were identified. These mitigation measures are part of the new fifty (50) year license and are required to be implemented during the duration of the license or until the mitigation projects are fully implemented.

    Both the Tribe and the State of Idaho have agreements with Avista for mitigation, including work that helps manage nutrients entering the lake. Specific project areas include: 1) stream bank and lake shoreline bank stabilization, 2) riparian restoration or replacement, 3) invasive weed management, 4) water quality monitoring, and 5) cultural resource protection.

  7. Increase Public Awareness of Lake Conditions and Influences on Water Quality.
  8. All of us recognize the need for good lake water quality. However, it’s critical for us all to understand how human activities such as construction, septic tank maintenance and drainfield performance, and the use of chemical fertilizers, impact our lake. This way, we can also understand how changes in our day-to-day activities can have a positive effect in our watershed.

    Our education efforts include partnering with the University of Idaho at the Community Water Resource Center on outreach and compilation of a water quality resource library; working with area schools, clubs, camps and organizations; developing the Coeur d’Alene Basin Lake*A*Syst program; and presentations to a multitude of community groups. To learn more about our education and outreach program, click here.