Coeur d'Alene Lake Subbasin
Subbasin at a Glance
|Hydrologic Unit Code||17010303|
|Size||651 square miles (416,333 acres)|
Water Bodies with EPA-Approved TMDLs (Category 4a)
Beauty Creek, Black Lake, Carlin Creek, Cedar Creek, Cottonwood Creek, Cougar Creek, Fernan Creek, Fernan Lake, Fourth of July Creek, Kidd Creek, Latour Creek, Marie Creek, Mica Creek, Rose Creek, tributaries to Coeur d’Alene Lake, tributaries to Killarney Lake, Wolf Lodge Creek
|Beneficial Uses Affected||Cold water aquatic life, salmonid spawning, primary contact recreation|
|Major Land Uses||Forestry, agriculture, urban|
|Date Approved by EPA||
|Date Black Lake TMDL Approved by EPA||
|Date 2012 Addendum Approved by EPA||
|Date 2013 Addendum Approved by EPA||
The Coeur d'Alene Lake subbasin includes Coeur d'Alene Lake, Coeur d'Alene River, and several tributaries to these two water bodies.
1999 Subbasin Assessment and TMDL
Following analysis of data and modeling results, 18 water bodies in the subbasin were verified to be water quality limited by at least one pollutant: eleven due to temperature, eight due to sediment, and one due to bacteria. The temperature TMDLs were deferred by the state until state temperature criteria are fully examined. The sediment limitations in the upper two segments of the Coeur d'Alene River are addressed in sediment TMDLs for the North and South Forks Coeur d'Alene River. Lake Creek, which is sediment limited, is wholly on the Coeur d'Alene Reservation, so it is not included in this TMDL. The five remaining segments limited by sediment are addressed here, as is the one segment limited by bacteria.
This TMDL deals solely with nonmetallic pollutants. A Coeur d’Alene Lake metals TMDL was developed in 2000 through a joint effort by DEQ and EPA but was overturned by the Idaho Supreme Court in a decision rendered in 2003.
1999 TMDL: Streams and Pollutants for Which TMDLs Were Developed
- Cougar Creek
- Kidd Creek
- Latour Creek (Including Baldy and Larch Creeks)
- Mica Creek
- Sediment, bacteria
- Wolf Lodge Creek (Including Marie and Cedar Creeks)
2011 Black Lake Watershed Assessment and TMDL
Black Lake, one of several lateral lakes along the Coeur d’Alene River, is approximately five miles west of Harrison, Idaho. The entire Black Lake watershed falls within Kootenai County, Idaho, in the Coeur d’Alene Lake subbasin and is approximately 16 square miles (10,282 acres). Approximately two-thirds of the Black Lake watershed is located within the Coeur d’Alene Reservation, including the two southern arms of Black Lake. Three primary tributaries drain to Black Lake: Porter Creek, Lamb Creek, and Black Creek. The land use/land cover in each subwatershed is primarily forested or used for agriculture. Only one percent of the Black Lake watershed has been developed.
A study of the physical, chemical, and biological conditions of Black Lake revealed that excess phosphorus in the lake is degrading water quality conditions by feeding nuisance aquatic plant growth that depletes oxygen important for fish. A beneficial use assessment demonstrated that the lake fails to support a viable aquatic life community for coldwater species and to support water quality conditions appropriate for recreational opportunities such as swimming.
To restore water quality in Black Lake, DEQ, the Coeur d’Alene Tribe, and the US Environmental Protection Agency (EPA) developed a TMDL to reduce sources of phosphorus in the lake. Since beneficial use assessments have not been conducted on Porter Creek, Lamb Creek, or Black Creek, insufficient data exist to determine support or nonsupport of beneficial uses for these small streams. Thus, TMDLs were not written for the Black Lake tributaries.
For this TMDL, the Coeur d’Alene Tribe has agreed to apply Idaho’s water quality standards as the basis for establishing an appropriate water quality target for nutrients in Black Lake. The Coeur d’Alene Tribe, EPA Region 10, and DEQ have agreed that the interpretation of the narrative criteria used in the TMDL will meet the criteria and protect the designated uses of both the Coeur d’Alene Tribe and the state of Idaho for Black Lake.
Meeting the pollutant load allocations for phosphorus discussed in this TMDL will require implementing various policies, programs, and projects and the cooperation of various entities, including tribal, federal, state, and local governments; irrigation companies; and private individuals. Implementation strategies are described in the document.
2011 TMDL: Water Bodies and Pollutants for Which TMDLs Were Developed
- Black Lake
- Total phosphorus
This 2011 addendum and update was completed in concert with the five-year review of the Coeur d’Alene Lake and River (17010303) Sub-basin Assessment and Proposed Total Maximum Daily Loads. The data collected as part of this subbasin assessment update were used to evaluate and make recommendations for beneficial use support status in Idaho’s 2010 Integrated Report for the Coeur d’Alene River and tributaries to the lake. While this effort does not include an evaluation of water quality and beneficial use support of Coeur d’Alene Lake, this document supports the Coeur d’Alene Lake Management Plan. No new TMDLs were developed with this effort.
This document addresses streams within the Coeur d’Alene Lake subbasin. In this subbasin, 22 assessment units (AUs) involving 14 major watersheds were identified as having temperature-related impairment and most have been placed on the §303(d) list of impaired waters (i.e., Category 5 of the Integrated Report) by the US Environmental Protection Agency (EPA) or the state for reasons associated with temperature criteria violations. This TMDL analysis addresses those streams included in Category 5 of Idaho’s 2010 Integrated Report as well as streams not listed but found to be impaired. The Idaho Department of Environmental Quality (DEQ) established effective shade targets for 20 AUs based on the concept of maximum shading under potential natural vegetation (PNV) resulting in the lowest possible natural stream temperatures. TMDLs were not developed for the two Coeur d’Alene River AUs because it is inappropriate to use PNV methodology on a river 50 meters wide or greater.
2012 Addendum: Streams and Pollutants for Which TMDLs Were Developed
- Cougar Creek
- North and South Forks Mica Creek
- Latour Creek and tributaries
- Fourth of July Creek
- Rose Creek
- Killarney Lake tributaries
- Blue Lake Creek
- Carlin Creek
- Beauty Creek
- Wolf Lodge Creek
- Cedar Creek
- Marie Creek
- Fernan Creek
This document addresses Fernan Lake within the Coeur d’Alene Lake subbasin. It updates the original subbasin assessment with information applicable to the Fernan Lake watershed and provides a TMDL analysis for the lake. Fernan Lake is currently listed as impaired by excess nutrients/eutrophication, which results in the occurrence of blue-green algae blooms and the lake not meeting its recreational beneficial use. The TMDL analysis quantifies pollutant sources and allocates responsibility for load reductions needed to return listed waters to a condition meeting water quality standards and full support of beneficial uses.
Fernan Lake blue-green algae blooms generally occur during late summer and fall. These blooms impair the lake’s recreational beneficial use by significantly reducing water clarity and causing unsightly, thick, green algal mats along shorelines. In addition, some species identified in Fernan Lake may produce toxins that are capable of causing illness and death to animals and illness to humans. The toxins may also affect fish and other aquatic life. This addendum established a total phosphorus TMDL for the lake, calling for a 35% reduction from all sources to meet the lake’s load capacity during the critical time period of August 15–September 15.
2013 Addendum: Streams and Pollutants for Which TMDLs Were Developed
- Fernan Lake
- Total phosphorus
- Coeur d'Alene Lake and River (17010303) Subbasin Assessment and Proposed Total Maximum Daily Loads (December 1999)
- Coeur d’Alene Lake and River Total Maximum Daily Load Implementation Plan (2002)
- Black Lake Watershed Assessment and Total Maximum Daily Load (March 2011)
- Coeur d’Alene Lake and River Total Maximum Daily Load and Subbasin Assessment: 2011 Addendum and Update (December 2011)
- Coeur d'Alene Lake Tributaries Temperature Total Maximum Daily Loads: Addendum to the Coeur d'Alene Lake Subbasin Assessment and Total Maximum Daily Loads (February 2012)
- Black Lake Watershed (Non-Reservation) Agricultural TMDL Implementation Plan (January 2014)
- Coeur d'Alene Lake Tributaries Temperature TMDL Agricultural Addendum Plan (August 2015)