Kootenai and Moyie Rivers Subbasins
Subbasins at a Glance
|Hydrologic Unit Codes||17010101, 17010104, 17010105|
|Size||1,080 square miles (691,200 acres)|
Water Bodies with EPA-Approved TMDLs (Category 4a)
Lower Kootenai River Subbasin: Ball Creek, Blue Joe Creek, Boulder Creek, Boundary Creek and tributaries, Brush Creek, Caribou Creek, Cow Creek, Curley Creek, Deep Creek, Fall Creek, Flemming Creek, Grass Creek, Long Canyon Creek, Lower Deep Creek, Mission Creek, Myrtle Creek, Rock Creek, Ruby Creek, Smith Creek, Snow Creek, Trail Creek, Trout Creek
Moyie River Subbasin: Canuck Creek, Deer Creek, Gillon Creek, Miller Creek, Meadow Creek, Moyie River tributaries, Round Prairie Creek, Skin Creek
|Beneficial Uses Affected||Cold water aquatic life, salmonid spawning|
|Major Land Uses||Timber harvest, recreation, designated wilderness, mineral extraction, dryland agriculture, rangeland|
|Date Approved by EPA||
|Addendum Approved by EPA||
The Lower Kootenai and Moyie River subbasins remained in a relatively natural condition until the early twentieth century when miners, loggers, and ranchers began to settle the area. In recent years, timber harvest and grazing have been restricted to the floodplain of the lower portion of the Kootenai River. Excessive sediment in the subbasin comes primarily from road crossings and encroachment. Temperature is most affected by stream shading. Metals and pH exceedances stem from historic mining activity near the headwaters of Blue Joe Creek.
2006 Subbasin Assessment and TMDL
Water temperatures are an issue in the Lower Kootenai and Moyie River subbasins. A subbasin assessment and TMDL for water temperatures was developed in 2005; however, before it was completed, the Kootenai and Moyie River Subbasin Watershed Advisory Group suggested it be incorporated into this TMDL.
An assessment of temperature data in 2002 indicated that all monitored streams in the Lower Kootenai and Moyie River subbasins exceed Idaho temperature criteria. When all streams, including undisrupted streams, have numeric criteria exceedances, a special look at natural conditions must be taken into account. The Lower Kootenai and Moyie River subbasins are located in the northern-most portion of Idaho at relatively low elevations. Throughout the state, it has been demonstrated that water temperatures are most strongly affected by air temperatures, which directly relate to elevation.
Metals and pH are identified as pollutants for Blue Joe Creek. During the initial 1998 assessment, Blue Joe Creek was void of aquatic insect life and was impaired. The source of metals and associated pH issues is the now abandoned Continental Mine. Through environmental cleanup activities, both DEQ and the US Forest Service have been working to reduce metals and pH loading. All reasonable TMDL implementation activities for metals and pH loading are complete, and Blue Joe Creek is in a state of recovery. Therefore, TMDLs for metals and pH for Blue Joe Creek were not developed.
The 1998 §303(d) list includes the Moyie River, from the Moyie River Dam to its confluence with the Kootenai River. Excess sediment is the listed pollutant, and based on the 1998 determination, a TMDL would be required. DEQ does not have Beneficial Use Reconnaissance Program (BURP) monitoring data on this section of the Moyie River and believes the sediment listing decision was based on anecdotal understandings and information. DEQ has evidence that the listing resulted from a single fine sediment deposition event and that the stream has recovered since that event. DEQ recommends removing the Moyie River from the §303(d) list and did not develop a TMDL for this river.
Blue Joe Creek, Boulder Creek, and Caribou Creek have also been removed as candidates for sediment TMDL development for the following reasons:
- Draft TMDLs demonstrated that current sediment generating conditions are better than those showing full support of the beneficial uses.
- Stressor Identification Analysis performed by DEQ supports removal of these three streams as TMDL candidates.
2006 TMDL: Streams and Pollutants for Which TMDLs Were Developed
- Boundary Creek
- Cow Creek
- Deep Creek
- Temperature, sediment
The Idaho Department of Environmental Quality (DEQ) has developed temperature TMDLs for 17 streams (23 AUs) in the Lower Kootenai River subbasin and 9 streams (11 AUs) in the Moyie River subbasin that were placed on the 2002 §303(d) list of impaired waters, or subsequent lists, for reasons associated with temperature criteria exceedances. In the Lower Kootenai River subbasin, 3 additional AUs that were not identified as being impaired by temperature pollution were included in this TMDL addendum as unlisted but impaired TMDLs (AUs ID17010104PN030_03, ID17010104PN033_03, and ID17010104PN039_02).
Effective target shade levels were established for 37 AUs based on the concept of maximum shading under potential natural vegetation resulting in natural background temperature levels. Shade targets were derived from effective shade curves developed for similar vegetation types in Idaho. Existing shade was determined from aerial photo interpretation that was partially field verified with Solar Pathfinder data. Target and existing shade levels were compared to determine the amount of shade needed to bring water bodies into compliance with temperature criteria in Idaho’s water quality standards (IDAPA 58.01.02).
In the Lower Kootenai River subbasin, 4 AUs previously listed for temperature pollution were found through stressor identification likely to be affected by pollutants other than temperature. These AUs will require additional monitoring and investigation. All other AUs in the Lower Kootenai River subbasin lack shade to some degree, although many reaches met reference conditions. Lowland streams affected by agricultural land uses (i.e., Cow, lower Fleming, Rock, and Curley Creeks) tend to be the most affected. Some forested systems (Boulder and Smith Creeks) have substantial hydrologic effects that widen streams and lower near-stream shade quality.
In the Moyie River subbasin, all AUs examined lack shade and most require substantial reductions in excess loads to meet targets. The Meadow Creek watershed appears to be in the best condition overall with respect to shade; whereas Deer Creek, Round Prairie Creek, and others have patches of shade deficits.
Target shade levels for individual stream segments should be the goal managers strive for with future implementation plans. Managers should focus on the largest differences between existing and target shade as locations to prioritize implementation efforts.
2014 Addendum: Streams and Pollutants for Which TMDLs Were Developed
Lower Kootenai River Subbasin
|Blue Joe Creek||ID17010104PN004_02||Temperature|
|Long Canyon Creek||ID17010104PN008_02||Temperature|
Moyie River Subbasin
|Moyie River Tributaries||ID17010105PN002_02
|Round Prairie Creek||ID17010105PN010_03||Temperature|
- Draft Kootenai River Total Maximum Daily Load Implementation Plan (November 2005)
- Assessment of Water Quality in Kootenai River and Moyie River Subbasins (TMDL) (September 2006)
- Assessment of Water Quality in Kootenai River and Moyie River Subbasins (TMDL): 2014 Addendum (June 2014)