The Montana Department of Environmental Quality has determined that Flathead Lake is a water quality-limited waterbody and that therefore a TMDL is required. The purpose of a Total Maximum Daily Load (TMDL) target is to establish quantifiable management measures to protect water quality and monitor how well water quality protection measures are working. This target will be used to guide decision making until better information becomes available. The goal of the TMDL is to achieve water quality standards through reduction or elimination of man-caused water quality impairments. The Confederated Salish and Kootenai Tribes have established water quality standards for the south half of Flathead Lake, but are not required to identify impaired waters requiring TMDLs. The Confederated Salish and Kootenai Tribes have determined that Flathead Lake is threatened, and are a cooperator in the Flathead Lake TMDL. All load and waste load allocations are based upon the standards in place for the specific area. In the case of draft waste load allocations for community waste water treatment facilities located solely in the state of Montana, non-degradation standards are based on Montana standards. They do not reflect standards of the Confederated Salish and Kootenai Tribes. The authors of the technical assessment (Stanford et al., 1997) conclude from their assessment that water quality in Flathead Lake remains on or near a threshold with respect to nutrient loading and resulting water quality. The study authors recognize that many factors other than nitrogen and phosphorus load influence alga growth in large lakes like Flathead, especially seasonal light availability, the strength of summer thermal stratification (i.e., depth of mixing during stratification) and food web interactions (i.e., availability of herbivorous zooplankton above the thermocline). Moreover, the physiology of alga growth where nutrient concentrations are below detection levels requires better resolution. Nonetheless, the inference that nutrient loads have to be reduced if the increasing trend in primary production is to be reversed and noxious algae (Anabaena) blooms prevented is based on very sound ecological science. The proposed interim Flathead Lake TMDL targets are expected to maintain high quality water in Flathead Lake. The interim TMDL targets are to be achieved within five (5) years. They are based on the long-term record of loads and in-lake responses. The interim targets for Flathead Lake measured in the photic zone at the mid-lake deep monitoring site are: | Proposed Interim Flathead Lake TMDL Targets | Primary production | 70.0 g C/m2/yr | Chl a | 1.0 micrograms/l | Soluble Reactive Phosphorous (SRP) | <0.5 micrograms/l (BDL) | Total Phosphorous | 5.0 micrograms/l | Total Nitrogen | 95 micrograms/l | Ammonia (NH3) | <1.0 micrograms/l | Nitrate/ Nitrite (NO2/3)nitrogen | 30 micrograms/l | No measurable blooms of Anabaena (or other pollution algae) | No oxygen depletion in the hypolimnion | Algal biomass measured as Chl a ( on near-shore rocks) remains stable or exhibits a declining trend. |
Top of page All targets are annual averages. Integrated samples for primary production, Chl a, SRP, total phosphorous, total nitrogen, ammonia and nitrate/nitrite must be collected within the mid-lake deep site photic zone. For an annual average to be considered valid, samples must be collected monthly during Spring, Summer, and Fall; at least one sample must be collected during the winter; a sample must be collected during the raising limb and the falling limb of the Flathead River hydrograph; and a minimum of twelve samples collected. Anabaena (or other pollution algae) blooms are measured at the surface. The interim TMDL was established using available information. The less scientific understanding one has of the sources of the pollution, the greater the adequate margin of safety needs to be. The interim target is set recognizing the uncertainty in the in our current understanding of the mechanisms controlling water quality as a conservative target. These TMDL targets are the interim targets recommended by a consensus of the members of the TMDL Team. The target is a starting point to begin the process of restoring water quality in Flathead Lake. While the adoption of the targets was not unanimous, the consensus of the TMDL team was that action is needed now. These targets will focus that effort. The proposed target was discussed at a TMDL Team meeting held on January 9, 1997. At a follow-up meeting held on March 7, 1997, the TMDL team decided to recommend the use of the target. There was a strong consensus among an overwhelming majority of the team members to recommend the use of the interim target. The Montana Department of Environmental Quality has the final responsibility for setting the TMDL for the Montana portion of the Basin. The U. S. Environmental Protection Agency, using standards adopted by the Confederated Salish and Kootenai Tribes and working closely with the Tribes for their concurrence, will establish the interim TMDL targets for the portion of Flathead Lake located on the Reservation. Further degradation of water quality in Flathead Lake poses a significant threat to the Lake as it remains at or near a threshold. A critical first step is to assure that no further increases in pollution loading are allowed. This preventative approach should guide decision-making until a permanent TMDL is adopted and a nutrient reduction strategy is in place. The achievement of this goal will require each new land use or development to assure that the new activity does not increase overall pollution loading and that new land use or development results in a decrease in loading to the Lake. Impairment Of Water Quality The impairment of Flathead Lake has been measured through four water quality changes: - During certain years, the lake experiences lake-wide algal blooms near the surface comprised of the blue-green pollution algae Anabaena flos-aquae.
| - Over the last several years, an oxygen sag has been measured in the vicinity of Big Arm Bay.
| - Near-shore rocks, once free of algae, now have become covered with algae annually.
| - The long-term trend in primary productivity is increasing.
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Each of these occurrences are recognized signs of water quality declines that can impact recreation and aesthetics. It is unclear as to the direct impact these signs of impairment have on aquatic life due to the complexity of the ecology of the Lake, lake pool manipulation and introduced species.
Naturally, low nutrient inputs to Flathead Lake result in extremely transparent water clarity, near-shore rocks free from algae and low primary productivity. As nutrient or pollution loading increases, the Lake's water quality undergoes significant changes while still remaining a "high" quality water body. The question of how much degradation is acceptable is problematic since thresholds are difficult to recover once they have been surpassed. The interim targets are at a level that will likely hold or restore the Lake to the conditions that existed when the Flathead Basin Commission was established. The adoption of a no net increase policy will assure that water quality conditions do not further deteriorate. The goals of the Flathead Lake TMDL targets are: - to maintain the lake free from late summer blooms of blue-green pollution algae;
| - to halt and reverse the long-term increase in primary productivity;
| - to assure no further increase in oxygen depletion levels in Big Arm Bay or anywhere else in the Lake; and
| - to reduce lake-wide inputs of nutrients contributing to the growth of algae occurring on rocks along the shoreline of the Lake.
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Additional bay-specific measures will likely be needed to fully address near-shore water quality degradation.
Top of page Data To Support TMDL Target The information used to establish the TMDL target recommendation was developed by the scientists at the University of Montana Flathead Lake Biological Station, Tribal, local, state and federal agencies. All recommendations and data assumptions were reviewed and discussed by the TMDL team. All comments from TMDL team members were reviewed and addressed. The recommendations are based upon the consultations and analyses conducted over the past 18 months through the EPA funded assessment. Separate investigations were undertaken by the Confederated Salish and Kootenai Tribes and form the basis for the lake-shore loading calculations. Long-term monitoring data collected by the University of Montana Flathead Lake Biological Station utilizing Flathead Basin Commission funding constituted the main body of information (Stanford et al., 1997). Top of page (1) Pollution Algal Blooms Blooms of algae in Flathead Lake are directly controlled by nitrogen and phosphorus loading. Reduce the load and the bloom intensity decreases and water clarity (quality) increases. Reduce the total propensity for the water to bloom and the possibility for Anabaena virtually disappears (unless we get a big late summer load from a climatic event that we have no control over). Phytoplankton, in Flathead Lake, annually blooms in the spring. This spring burst of activity is part of the historical cycle of the Lake. On most years, the spring algal bloom simply uses all of its available nutrient pool and the summer blooms are not noticeable. During these types of years, high water quality is maintained. On a few years, this spring burst of activity is followed by a summer bloom of the pollution alga Anabaena, especially if summer nutrient inputs are high. The proposed TMDL target is directed primarily at stopping the late summer blue-green algal bloom by reducing nutrient loads that drives the bloom. Late summer blue-green algal blooms are visible to anyone who visits the Lake and is recognized as a water quality problem. Stanford et al., (1997) showed that these blooms of pollution algae did not occur lake-wide until the 1980s when loads from human sources increased with increases in land disturbance and development. To halt the frequency and duration of these blooms, annual loading must be reduced. The scientists concluded that open water blooms of Anabaena did not occur until the 1970s at the earliest and none of the previous studies reported blooms extensive enough to cause scums to windrow as was observed in 1983 and 1993. Top of page (2) Big Arm Bay Oxygen Deficit As primary production increases in response to nitrogen and phosphorus, more biomass is present in the water column. Biomass constantly settles into the dark, cold bottom layers where it is decomposed by bacteria. These bacteria consume oxygen as they grow on the phytoplankton produced in the photic (lighted) zone of the water column. The more biomass consumed - the more oxygen the bacteria require. Over the past several years, an area of Big Arm Bay has exhibited oxygen depletion in late summer. This is a clear sign of deteriorating water quality, probably related to nitrogen, phosphorus and carbon loading. The carbon could be associated with organic material breaking-down and being carried to the Lake from the watershed or associated with increases in lake biomass. It is not clear at this time what the exact sources are for the pollution loading causing this oxygen deficit. It could be inputs from the Flathead and Swan Rivers, inputs from the airshed or inputs from Dayton Creek, or some combination of all of these sources. Top of page (3) Near-shore Bottom Algae Growth The existence of periphyton, or algae growing on near-shore rocks is one of the frequently cited signs of water quality degradation in Flathead Lake. Many people who have lived around the shoreline of Flathead Lake for many years can remember when the area in front of their property was free from algae growing on the shallow-water rocks. While it was recognized that this algae growth signifies a water quality impairment, little quantifiable historical information exists on which to base water quality management decisions. The establishment of a monitoring program is needed to remedy this situation. Ten locations around the perimeter of Flathead Lake were selected for preliminary monitoring of periphyton biomass in August 1995, June and August 1996. The goal was to determine which sites would best serve as long-term sites for monitoring periphyton growth and to examine the distribution of periphyton growth lakewide. Periphyton biomass can provide insight into loading from shoreline point and nonpoint source pollution as well as indicators of loading accumulating from upstream sources. The results obtained from periphyton monitoring can reflect localized sources of nutrients. Excessive growth of periphyton in areas which do not have nearby contaminated streams or groundwater seeps might indicate above normal export of nutrients from land use activities. While, the water quality impairment associated with the growth of algae on near-shore rocks is well recognized, it is not currently possible to assess water quality control measures. Periphyton is likely to become a more widely used measure of water quality health in Flathead Lake in the future. It is possible that periphyton growth could be a more sensitive indicator of nutrient loading than phytoplankton growth to the near shore areas and bays. Top of page (4) Long-term Primary Production Increases The response of the lake's primary production to nutrient (pollution) loading is complex. It involves light dynamics produced by seasonality and river turbidity. In addition, the external nitrogen and phosphorus (point, nonpoint and natural loading) and internal nutrient supply play a major role on lake water quality. Over the period of record, annual primary productivity has varied between 62 and 138 g C/m2/yr (Table II- 1) with a gradually increasing trend. Table II-1
Flathead Lake Primary Productivity measured at Mid-Lake Deep SiteSource: UMFLBS | Year | gC/m2 | 1978 | 76 | 1979 | | 1980 | | 1981 | | 1982 | 73 | 1983 | No funding for PP estimate. Major Anabena bloom. | 1984 | | 1985 | 88 | 1986 | 66 | 1987 | 94 | 1988 | 136 | 1989 | 93 | 1990 | 97 Minor Anabaena bloom. | 1991 | 106 Minor Anabaena bloom. | 1992 | 101 | 1993 | 90 Major Anabaena bloom. | 1994 | 85 | 1995 | 87 | 1996 | No funding for PP estimate. |
Top of page Primary productivity accurately predicts biomass (chl a) and is strongly linked to the nutrient load reaching Flathead Lake annually. For the period 1989 to 1995, a significant linear relation between primary production and phosphorus load was documented by Stanford et al., 1997. The period from 1977 to 1988 is less clear since it appears the relation was skewed by food web changes caused by introduction of Mysis shrimp. The long term record of primary productivity in Flathead Lake is a robust indicator of water quality that is strongly influenced by external nutrient loads. Derivation Of TMDL Targets During the current period while the lake monitoring continues, it is possible to establish interim targets to protect and restore water quality in Flathead Lake. Loading targets are recommended at levels to keep Flathead Lake away from its pollution algae threshold based on the science in hand. Targets will be monitored in the photic zone of the mid-lake deep site. This site represents overall water quality conditions in the lake. If conditions are maintained at these levels, a blue-green algal bloom is not likely to occur, and the oxygen sag will not worsen to the point where bottom nutrients are released into the water column. A similar positive affect should be measured in the growth of near-shore algae. This target may or may not be sufficient to address impairment related to periphyton growth along shorelines since this pollution event is closely linked to site specific conditions occurring in individual bays. Measured annually, a 70 gC/m2/year primary productivity target represents a reduction commensurate with the 15 percent reduction achieved by the community waste water treatment plants in the Basin. As an interim target and goal to guide management decisions it is a conservative approach that will need to be refined as we learn more through monitoring and in response to measures taken to protect the Lake's water quality. While the target and reduction goal needs to guide long-range decision-making, an interim objective should be "no increase" over current nutrient loading where every new land use or development must demonstrate a commensurate reduction of pollution loading. Recent declines in primary production could be related to reductions in the nitrogen and phosphorus loads as a consequence of construction of new wastewater treatment facilities in the Basin which came on line in the early 1990s. The contribution of community sewage treatment plants to the total phosphorus load declined by about 12% with the implementation of new nutrient removal technologies (Stanford et al., 1995). The new plant in Kalispell, which now also serves part of the Evergreen community, produces very good effluents. Nutrient concentrations in Ashley Creek below the plant outfall have improved significantly. Similar improvements in the Evergreen aquifer are expected but they have not been observed to date. However, in spite of these reductions the pollution alga Anabaena bloomed extensively in 1993. That summer was wet and nonpoint loading contributed significantly to summer loads. 1993 represents a year when primary productivity levels failed to protect the Lake against an Anabaena bloom. It is a level of pollution loading that must be avoided in the future. This base year represents unacceptable water quality impairment. Top of page Allocation Of Flathead Lake Loads To Sources The Total Maximum Daily Load is a tool to implement water quality standards. It is based on the relationship between pollution sources and in-lake water quality conditions. The TMDL establishes the allowable loading of nitrogen and phosphorus and thereby provides the basis to establish water quality-based controls. The base year used for the TMDL loading estimates is 1993. This base was chosen since it is a year that resulted in measurable water quality impairment of Flathead Lake. A lake-wide pollution algae bloom occurred during the Summer of 1993. Reductions in pollution loading need to assure that man-caused conditions that existed in 1993 are avoided in the future. The total annual load for Flathead Lake from all sources in the Basin (based upon calculations prepared by Stanford et al., 1997 and discussed by the TMDL Team) was estimated to be 123 tons of total phosphorous (average 673.97 lb/day) and 1467.4 tons of total nitrogen (average 8040.55 lb/day) (Table II-2). It is important to recognize that we are unable to control the natural loads. Water quality management activity needs to focus on the man-caused loads even though the total load is the estimated nutrient supply to the lake. The man-caused portion of the loads in the Lake can be thought of as the pollution load to the lake. For example, fertilizer placed on a crop is a nutrient. If that nutrient escapes unused from the agricultural site and flows into the river system, it becomes a pollution load. A goal of all point and nonpoint control measures is to trap and utilize these nutrients on the land and to keep them from entering Flathead Lake. The natural load makes up the vast amount of nutrient input to the Lake. This is to be expected since much of the area is dominated by natural conditions. Sixty-four percent (64%) of the total phosphorus load is estimated to come from natural sources while fifty-nine percent (59%) of the total nitrogen load is derived from natural or background sources. Concentrating on the man-caused portion of the load, the TMDL can be allocated between point sources (waste load allocation) and nonpoint sources (load allocation). Nonpoint sources rural road run-off, on-site septic systems, shoreline clearing, lost riparian areas, wetland draining, livestock grazing, farming, timber harvest and all land disturbing activities that are not controlled by point source water quality discharge permits. Filling a gray area includes things such as urban stormwater, while considered a point source, is not regulated in the Flathead Basin and; therefore, is included in the nonpoint load estimates. The nonpoint load estimates include man-induced inputs from the airshed, shoreline areas in the immediate Flathead Lake watershed, the valley area above the Lake outside of municipalities, the Evergreen aquifer, and areas of forest disturbed by roading and timber harvests. The airshed loading includes both dry-fall and precipitation. It is not possible to determine if the airshed load comes from sources within the Basin or from long-distances away. The airshed annual estimates are 19.7 tons of total phosphorus (average 107.95 lb/day) and 74.4 tons of total nitrogen (average 407.67 lb/day). The shoreline estimate is a gross approximation that includes both natural and man-induced loads. It is not possible with current data to make more refined calculations. It has long been thought that near-lake pollution loading was significant, but until the TMDL studies by the Biological Station (Stanford et al., 1997) and the Confederated Salish and Kootenai Tribes (Makepeace and Mladenich, 1996) were completed, even a gross estimate was not possible. The phosphorus and nitrogen loads averaged for low and high attenuation/load scenarios from the Tribes study were added to estimates for shoreline creeks to calculate shoreline loads (Stanford et al., 1983). The shoreline annual estimates are 6.0 tons of total phosphorus (average 32.88 lb/day) and 44.6 tons of total nitrogen (average 244.38 lb/day). The semi-rural area above the Lake includes the valley-bottom areas to Columbia Falls and Whitefish on the north and the mountains to the east and west. This estimate includes the Stillwater, Whitefish, Ashley, Blaine and Mill sub-watersheds. It includes the areas experiencing a bulk of the residential and commercial growth outside of cities and the agricultural areas of the Basin. Nutrient loads determined during base flow and the rising limb synoptics at sites above primary semi-urban areas were subtracted from nutrient loads at tributary mouths. Loads from community waste water treatment plants were subtracted from the loads and apportioned over the annual hydrograph for the 1993 water year. Annual hydrographs were not available for Mill and Blaine Creeks, thus calculated loads were apportioned over a 10 month period for base flow and a 2 month period for rising and peak flows. The non-urban valley above the Lake annual estimates are 7.5 tons of total phosphorus (average 41.1 lb/day) and 84.2 tons of total nitrogen (average 461.37 lb/day). The Evergreen aquifer has been recognized as a significant source of nutrients to the Flathead River above the Lake. The southern area of Evergreen below Western Reserve Drive no longer relies upon individual septic systems and has been connected to the Kalispell waster water treatment facility. The area above Western Reserve Drive continues to grow and develop relying upon individual septic systems and on-site waste water treatment systems. Extensive sampling and analysis was completed prior to connecting to the Kalispell facility. A well monitoring system established in the 1980s was re-sampled to see how conditions had changed. Based upon a mean annual nitrate concentration of 0.76mg/L and a mean phosphorus value of 10.5mg/L (Noble and Stanford, 1986) and a discharge estimated at 0.21 cubic m/sec (Roger Noble, personal communication), the aquifer was estimated to contribute 0.08 tons of total phosphorus (average 0.4 lb/day) and 5.0 tons nitrate (average 27.4 lb/day). The managed forested areas of the Basin are the other major source of loading to the Lake. The forested area of the Flathead Basin is 3,905,200 acres. This forested area can be divided into managed and unmanaged areas. The unmanaged areas are in wilderness (national forest and Glacier National Park). Wilderness comprises 1,649,393 acres or 42.2 percent of the forested area. The remaining 2,255,807 acres are considered managed forest. The load from managed forest was estimated by adding the loads for the semi-urban areas and Evergreen aquifer and subtracting it from the total river load. The resultant load was multiplied by the percent of forested area within the managed forest. The annual load from managed forest was estimated at 48 tons of total phosphorus (average 264 lb/day); and 705 tons of total nitrogen (average 3862 lb/day). The wilderness areas contributed annually 35 tons total phosphorus (average 193 lb/day); and 524 tons of total nitrogen (2875 lb/day). Within the managed forest area, those areas where timber management activity occurred within the past five years were identified as disturbed. Nutrient concentrations were compared in disturbed and undisturbed drainages of the Middle Fork of the Flathead River and Swan River during the synoptics of August 1995. Average nutrient concentrations from undisturbed drainages were subtracted from average nutrient concentrations from disturbed drainages within each river corridor. The differences observed in the Middle Fork and the Swan for each nutrient were averaged and used to calculate a disturbance factor. These disturbance factors were multiplied by the annual load from managed forest lands to arrive at a disturbance load. The disturbance factors used were 0.162 for total phosphorus, 0.677 for nitrate-nitrite and 0.524 for total nitrogen. The annual load estimated to come from forest disturbance was 7.8 tons total phosphorus (average 42.74 lb/day); and 369.36 tons total nitrogen (average 2023.89 lb/day). The load allocations for the forested areas of the watershed were the subject of considerable discussion by the TMDL Team. A special meeting was held on March 7, 1997, with a primary focus on the forestry allocations. A number of methodologies were considered to calculate loading from forested areas. After lengthy discussions, a majority of the TMDL team concluded that these other approaches resulted in more uncertainty than the method described. The annual load for forest lands disturbance was subtracted from the total annual load from managed forest lands to calculate background for managed forest areas. The wilderness annual load totals were added to this to obtain background or natural estimates for the forested areas. The background for forested areas was 75.64 tons total phosphorus, and 850.2 tons total nitrogen annually. It is important to recognize that the estimates for forestry related nonpoint loads were developed using basin-wide loading factors. Additional investigations are necessary if precise measurements of loads between disturbed managed and unmanaged forested areas are going to be used to guide water quality management decisions. In the Flathead River Basin, the only substantial or measured point source loads come from the waste water treatment plants. Facilities that discharge into waters flowing into the lake are the facilities for the communities of Bigfork, Columbia Falls, Kalispell, Whitefish and Yellow Bay. The total waste load for the 1993 base year was 2.5 tons of total phosphorous (average 13.74 lb/day) and 4.22 tons of total nitrogen (average 23.12 lb/day). It should be noted that the total nitrogen loading measurements do not include the Bigfork waste water treatment plant since it did not monitor for this nutrient. A sixth community waste water treatment facility serves the Lakeside-Somers area. This facility discharges to the soil (land application). Monitoring wells located around the perimeter of the Lakeside-Somers facility has not detected the movement of nutrients from the facility and; therefore, no loading is allocated to it. The nutrient or pollutant loading from all nonpoint sources for the 1993 base year was 41.08 tons of total phosphorous (average 225.1 lb/day) and 572.6 tons of total nitrogen (average 3,137.53 lb/day). This loading includes all man-induced nutrient loading. Nutrients are the basic building blocks for all life in a water body. The natural loading rates support the lake as it historically existed in the Basin. Excess loading of nutrients or pollutant loading represents the human-induced loading occurring in the Lake. It is this human-induced loading, whether from community waste water treatment facilities or from nonpoint sources throughout the Basin, that must be reduced to protect lake water quality. It is this excess loading that causes the declining water quality found in the Lake today. Table II-2
Flathead Lake Watershed Load Allocations -- 1993 Base Year
Source: TMDL Team, 1996 & 1997 | Load | Total
Phosphorus | Nitrate/nitrite | Total
Nitrogen | Nonpoint | . | . | . | Airshed disturbance | 9.7 | 35.2 | 74.44 | Shoreline background & disturbance | 6.0 | 36.2 | 44.6 | Semi-rural (valley above lake) | 7.5 | 88.0 | 84.2 | Evergreen Acquifer | 0.08 | 5.0 | | Managed forest distrubed | 7.8 | 196.5 | 369.4 | Waste | . | . | . | Sewage treatment plants | 2.5 | 7 | 23.4 | Natural** | . | . | . | Forest | 75.6 | 305.7 | 850.2 | Airshed | 3.1 | 16.2 | 21.2 | Totals | 122.8 | 689.90 | 1467.40 | * Includes point source community storm water. ** Natural only includes airshed and forested areas. |
Top of page The level of reduction needed to protect the Lake is commensurate with the levels achieved by the community waste water treatment plants through implementation of the 1986 Flathead Lake Phosphorous Strategy. Community waste water treatment plants have achieved the state mandated phosphorous limit of 1mg/L. All of the facilities in the Basin meet or surpass this standard on an annual basis. The city of Kalispell routinely exceeds this standard meeting levels closer to 0.2 mg/L for total phosphorous and has voluntarily undertaken active nitrogen removal. The waste water treatment facilities have reduced pollution loading 70 to 90 percent. Community facilities have also played a significant role in reducing nonpoint loading. Reductions in nonpoint loading through the development of new systems (Lakeside- Somers) and the expansion of sewered areas such as the Evergreen, Big Mountain/ Whitefish Lake and areas around Bigfork have each played a major role in protecting water quality. As part of the next phase of TMDL development, the people living in the Basin will need to identify additional measures to take to restore the degraded water quality in Flathead Lake and throughout many of the lakes, rivers and streams that flow into the Lake. Numerous opportunities exist to address nonpoint pollution loading. In the future, water quality protection will increasingly need to rely upon more and more people joining together to address what seem to be individually small isolated contributions to water quality degradation. Communities in the Basin can do more to control point source pollution associated with storm water and to minimize new nonpoint source pollution. Additional gains from community waste water treatment plants will come primarily from the construction of entirely new facilities when capacity is exceeded or through extending service to areas currently relying upon on-site disposal (provided community systems obtain a higher level of nutrient removal). The technical studies conducted to support development of this TMDL (Stanford et al., 1997) show that water quality substantially deteriorates (up to 72% increase in load) in the Stillwater and Whitefish Rivers and Ashley Creek as those tributaries flow through the Kalispell Valley. This loading increase is highly significant. In the Kalispell Valley, nitrate/nitrite loads increase by up to 91 times (excluding the August 1996 synoptic for Ashley Creek which showed an increase of 528 times) over background in the agricultural and semi-urban reaches of the Whitefish River, the Stillwater River and Ashley Creek. Increases in total phosphorus and total nitrogen loads were generally much lower with maximum increases of 5.5 times and 5.1 times, respectively, over background. In a healthy river system through an open-canopied valley such as the valley above the Lake, nutrient loading should decrease as riparian areas trap, use and store nutrients. Instead, loading increases from top to bottom. This finding coupled with a knowledge of the types of soils found in the valley indicates that much of this pollution loading is attributable to nonpoint pollution. The TMDL team concluded that the extension of community waste water treatment to areas currently relying upon individual septic systems could play a significant role in restoring Flathead Lake since community waste water treatment facilities are required to achieve a higher level of treatment than is possible with on-site septic systems. The TMDL team recommended that in setting reduction targets that growth in community waste water treatment be allowed and encouraged, provided the required higher level of treatment is attained. Adoption of this strategy could represent a first step in meeting the no further degradation goal. The Montana Department of Environmental Quality issues National Pollution Discharge Elimination System permits for each waste water treatment facility in the basin. These permits establish a non-degradation limit for both phosphorous and nitrogen loading from each facility. These non-degradation limits establish an upper limit to guide load allocations and allocate reduction targets. They are included to guide further discussion, provide an interim waste load target and facilitate development of a plan to protect and restore Flathead Lake's water quality. Using the state calculated permit limitations for each facility, the loading for total phosphorus from community waste water treatment facilities could increase from the base year load of 2.5 tons annually to 8.9 tons annually (Table II-3). The calculated increase represents the maximum load at treatment plant capacity. This is over a four-fold increase in loading from community waste water treatment facilities. If this loading is allowed to increase, it will need to be closely monitored to assure other off-sets in pollution loading are achieved. A trade-off scheme will need to be identified during the development of the Voluntary Nutrient Reduction Strategy. Approximately 1.2 tons of phosphorous represents about 1% of the annual load. If community waste water treatment increases loading by 6.63 tons, an additional 3% reduction will be needed from nonpoint sources. This load reduction may be partially offset by the elimination of existing septic systems and offset through enhanced treatment from the community systems. Table II-3
Calculated Waste Loads for Waste Water Treatment Plants Waste Load
(calculations provided by DEQ based upon design capacity) | Plant | Total daily
phosphorus
(pounds) | Annual
phosphorus
(tons) | Total daily
nitrogen
(pounds) | Annual
nitrogen
(tons) | Whitefish | 10.4 | 1.9 | 280.0 | 51.0 | Columbia Falls | 6.0 | 1.1 | 140.0 | 25.5 | Bigfork | 4.2 | 0.8 | 152.0 | 27.7 | Yellow Bay | 2.0 | 0.4 | 7.9 | 1.4 | Kalispell | 25.85 | 4.7 | 890.0 | 42.4 | Totals | 48.45 | 8.9 | 469.9 | 147.8 |
Top of page Closely related to decisions concerning community waste water treatment facilities and nonpoint pollution control measures is stormwater run-off. Stormwater in certain instances is collected and treated at the community waste water treatment facility. In other instances, sediment basins have been constructed or run directly into a stream or river. Stormwater represents one of those instances where doing a little can add up to a lot. A single stormwater event does not appear to be a major part of the Lake's nutrient load, but each event can have a major "shock effect". Metals and nutrient concentrations have been measured above EPA benchmark values. Although no benchmark value exists for fecal coliform bacteria, several sites in Kalispell and Whitefish have more than 400 fecal coliform bacteria per 100 milliliter. Stormwater control and treatment will require close scrutiny as part of the nutrient reduction strategy development. Go to Sections III & IV of TMDL Report | 
