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Flathead Lake is an outstanding aquatic resource. The lake remains among the cleanest large lakes in temperate regions world wide. But research shows that water quality in Flathead Lake has been steadily declining since 1977. Primary productivity, or the rate of algae growth, is increasing according to Flathead Lake Biological Station Director Dr. Jack Stanford. And the amount of dissolved oxygen in water at the bottom of Big Arm Bay is declining. These two trends are indications of declining water quality. Phosphorus and nitrogen are nutrients that contribute to algae growth. Past efforts to reduce the amount of nutrients reaching Flathead Lake and its tributaries have been successful. Upgrading sewage treatment plants in the upper basin for phosphorus removal, hooking up Evergreen (an unincorporated semi-urban area) to the Kalispell sewer system, and banning domestic use of phosphorus-containing detergents have reduced the amount of nutrients reaching Flathead Lake from these sources. However, water quality continues to decline primarily due to polluted runoff.
Polluted runoff, also known as nonpoint source pollution, is now our leading threat to water quality. It is caused by rainfall or snowmelt moving over and through the ground. As it moves, runoff picks up and carries natural and human-caused pollutants, finally depositing them into rivers, lakes and groundwater. Croplands, livestock feedlots, golf courses, lawns, gardens, roadways, parking lots, construction sites, landfills, city storm sewers, logging operations, residential septic systems, and erosion from streams, river-banks and lake shores are all sources of polluted runoff. Even airborne chemicals and particulates carried into our waters by rain or snow contribute to the problem. The scattered locations of these pollutants and their often unpredictable dispersal make clean up efforts complex and often costly. This is because the waterways within a watershed are interconnected - streams flow into rivers, which flow into lakes. And there can be a connection between these surfaces waters and groundwater. A pollutant introduced in one area upstream can pollute the water downstream. Farms and cities rank as the major sources of polluted runoff, according to the Environmental Protection Agency (EPA). Studies by the University of Montana's Flathead Lake Biological Station confirm this. They have found that the valley area north of Flathead Lake is contributing a large share of the polluted runoff that eventually reaches Flathead Lake. Pollutants from agriculture can include pesticides, nutrients from fertilizers, sediment from soil erosion, and bacteria and nutrients from manure. Pollutants come from urban and suburban areas through the use of pesticides and fertilizers in maintaining lawns and gardens. Streets and parking lots accumulate gasoline, lead, oil, and grease from automobiles, contributing to polluted runoff following heavy rains.
The solution lies in the prevention of pollution through the collective responsibility of individuals, governments and corporations. If each group and family takes responsibility for the lands they manage and the pollution they generate, polluted runoff can be reduced. When the land is covered with crops, shrubs and trees, these plants take up and use the nutrients, keeping them from reaching the groundwater, streams, and eventually Flathead Lake. If we don't act now, cleaning up a polluted Flathead Lake in the future will be prohibitively expensive and enormously complex. Preventing pollution is the sensible course. Everyone has an important role.
How informed are you about water pollution? Where is the pollution in the runoff coming from? For answers to these questions, go to our Polluted Runoff page.
Flathead Lake was listed as an impaired water body by the Montana Department of Environmental Quality (MDEQ 303d List) in 1996 and 2000. Consequently, Total Maximum Daily Loads (TMDL), or the maximum amount of pollutants that may be present in the water and still meet water quality standards, were determined for Flathead Lake to guide restoration efforts and to reduce excess nutrients reaching Flathead Lake. Further watershed assessments are proposed by the Flathead Basin Commission, to identify specific nutrient sources and nutrient reduction strategies. The Flathead Basin Commission <link> is a non-regulatory organization formed by the Montana Legislature in 1983 to monitor and protect water quality in the Flathead Basin. Lake-wide blooms of pollution algae occurred twice in the past. In 1998, the amount of primary production was the second highest ever recorded. The levels of dissolved oxygen in Big Arm Bay were the lowest ever recorded. Blooms of a pollution algae (Anabaena flosaquae) were observed near shore. And nitrogen concentrations in the Stillwater and Flathead rivers were among the highest ever recorded. The 303(d) List identified the probable causes of impairment as: nutrients, siltation, suspended solids, flow alteration, organic enrichment or low dissolved oxygen, algal growth, PCBs, metals, mercury, and noxious aquatic plants. The main sources of pollution include runoff from urban sprawl, old and poorly maintained septic systems, poor agricultural and timber harvest practices, and air pollution.
| | 303(d) List | Probable Uses Impaired | Probable Causes | | 1996 | Aquatic life support | Flow alteration
Noxious aquatic plants
Nutrients
Siltation
Suspended Solids
| | 2000 | Aquatic life support | Nutrients
Siltation
Organic enrichment/low DO
Algal growth/Chlorophyll a
PCBs
Metals
Mercury | MDEQ, 2001. Nutrient Management Plan and TMDL for Flathead Lake, Montana |
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Other water bodies listed in the Montana 1996 & 2000 303(d) Lists include several rivers, streams and lakes in the Swan and Stillwater drainages and other Flathead waters, including the drainages of the three forks of the Flathead River and the mainstem of the Flathead River (Montana DEQ Website, 1996). TMDL studies must also be conducted for these drainages to determine the degree of impairment and to guide water quality restoration efforts. Every year, Professor Jack Stanford presents his State of the Lake report, an annual summation of the lake's condition, at the Flathead Lakers Annual Meeting. The State of the Lake reports from 1998 through the present are available online:
The Montana Department of Environmental Quality (DEQ) identified Flathead Lake as a waterbody that is not fully meeting state water quality standards. Consequently, the Montana Department of Environmental Quality (DEQ) prepared a report, the Draft Nutrient Management Plan and Total Maximum Daily Load (TMDL) for Flathead Lake, Montana. The plan is required for impaired water bodies by the Clean Water Act (Section 101). The act's goal is "to restore and maintain the chemical, physical, and biological integrity of the nations waters." This plan establishes targets for the maximum amount of nutrients (phosphorus and nitrogen) Flathead Lake can receive and still avoid water quality deterioration and algae growth. It also provides strategies for managing nutrient loads. Learn more about the TMDL for Flathead Lake (on old Lakers website) or download the TMDL report from the Department of Environmental Quality's website (opens in new window).
Monitoring water quality in Flathead Lake and its tributaries is important to understand long-term trends. Only then can we understand whether water quality is getting worse or better. Monitoring is also important to document the effectiveness of protection and restoration activities to reduce pollution. More information:Lakers water quality monitoring pages.
The Flathead Basin Commission has volunteer programs monitoring lakes, streams and wetlands throughout the Flathead Watershed. The FBC's website has more information. There is also a story on the volunteer monitoring program in the Summer, 2005, issue of the Flathead Laker's newsletter. What can you do? Let your local legislators know that monitoring the quality of Flathead Lake and its tributaries is important to you.
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