Title

Overview of the Flathead Lake Voluntary Nutrient Reduction Strategy

Abstract

If you ask Montanans which five Montana lakes are the most important or valuable, invariably Flathead Lake is in the top three picks. The lake's size, beauty, recreation benefits, and excellent water quality increase local real estate values and make it a popular destination. However, few Montanans know that Flathead Lake currently does not meet State water quality standards (ARM 17.30.637 (1)(e)General Prohibitions), and is undergoing the eutrophication process at an accelerated rate. Excess nutrients (phosphorus and nitrogen) stimulate algal blooms and serious oxygen depletion of the deep waters. Extensive lake and stream water quality monitoring document that nonpoint source pollution is degrading water quality, interfering with beneficial uses, and causing violation of water quality standards. As a result, Flathead Lake is included on the Clean Water Act’s Section 303(d) list of water-quality-impaired waterbodies, and is a high priority for developing a water quality restoration plan (called a Total Maximum Daily Load or TMDL). Such a plan is close to completion.

Probable sources of water quality impairment include atmospheric deposition, domestic wastewater lagoons, flow regulation/modification, municipal point sources, on-site wastewater treatment systems (septic tanks), urban sprawl, overland runoff, agriculture, silvaculture, and an upstream impoundment. Only 2 percent of the nutrient load in Flathead Lake is estimated to come from point sources. The vast majority of nutrients come from natural sources or human-caused nonpoint source pollution. To address nonpoint source pollution, the Flathead Basin Commission (FBC) developed the Voluntary Nutrient Reduction Strategy (VNRS), and linked it to the TMDL process. The goal of the VNRS is to achieve the 1978 lake primary productivity level of 80 grams carbon/m2/year. This level is expected to yield water quality that meets water quality standards and supports beneficial uses (including swimming and aquatic life support). To meet the target primary productivity, the FBC determined that nitrogen (including nitrate plus nitrite) and phosphorus loading must be reduced by 15 percent basin wide. Six principal components for successful implementation of the ongoing VNRS/TMDL program include:

(1) coordination and planning, (2) grant funding & contributions (3) partnerships and public outreach, (4) participation of watershed groups, (5) identification of opportunities, and (6) monitoring. History, implementation and achievements of the Flathead Basin VNRS/TMDL are described in this paper.

Start Date

14-4-2000 12:00 AM

End Date

14-4-2000 12:00 AM

Document Type

Poster

 
Apr 14th, 12:00 AM Apr 14th, 12:00 AM

Overview of the Flathead Lake Voluntary Nutrient Reduction Strategy

If you ask Montanans which five Montana lakes are the most important or valuable, invariably Flathead Lake is in the top three picks. The lake's size, beauty, recreation benefits, and excellent water quality increase local real estate values and make it a popular destination. However, few Montanans know that Flathead Lake currently does not meet State water quality standards (ARM 17.30.637 (1)(e)General Prohibitions), and is undergoing the eutrophication process at an accelerated rate. Excess nutrients (phosphorus and nitrogen) stimulate algal blooms and serious oxygen depletion of the deep waters. Extensive lake and stream water quality monitoring document that nonpoint source pollution is degrading water quality, interfering with beneficial uses, and causing violation of water quality standards. As a result, Flathead Lake is included on the Clean Water Act’s Section 303(d) list of water-quality-impaired waterbodies, and is a high priority for developing a water quality restoration plan (called a Total Maximum Daily Load or TMDL). Such a plan is close to completion.

Probable sources of water quality impairment include atmospheric deposition, domestic wastewater lagoons, flow regulation/modification, municipal point sources, on-site wastewater treatment systems (septic tanks), urban sprawl, overland runoff, agriculture, silvaculture, and an upstream impoundment. Only 2 percent of the nutrient load in Flathead Lake is estimated to come from point sources. The vast majority of nutrients come from natural sources or human-caused nonpoint source pollution. To address nonpoint source pollution, the Flathead Basin Commission (FBC) developed the Voluntary Nutrient Reduction Strategy (VNRS), and linked it to the TMDL process. The goal of the VNRS is to achieve the 1978 lake primary productivity level of 80 grams carbon/m2/year. This level is expected to yield water quality that meets water quality standards and supports beneficial uses (including swimming and aquatic life support). To meet the target primary productivity, the FBC determined that nitrogen (including nitrate plus nitrite) and phosphorus loading must be reduced by 15 percent basin wide. Six principal components for successful implementation of the ongoing VNRS/TMDL program include:

(1) coordination and planning, (2) grant funding & contributions (3) partnerships and public outreach, (4) participation of watershed groups, (5) identification of opportunities, and (6) monitoring. History, implementation and achievements of the Flathead Basin VNRS/TMDL are described in this paper.