ARM 17.30.631. NUMERIC ALGAL BIOMASS AND NUTRIENT STANDARDS

(1) No person may violate the numeric water quality standards identified below. (2) The numeric nutrient and standing crop of benthic algae water quality standards for the mainstem Clark Fork River from below the Warm Springs Creek confluence (N46º11'17", W112º46'03") to the confluence with the Flathead River (N47º21'45", W114º46'43") are as follows: (a) In the mainstem Clark Fork River from below the Warm Springs Creek confluence (N46º11'17", W112º46'03") to the confluence with the Blackfoot River (N46º52'19", W113º53'35") the numeric water quality standards for Total Nitrogen, Total Phosphorus, and benthic algal chlorophyll a, applicable from June 21 to September 21, are as follows: (i) Parameter Concentration Total Phosphorus as P 20 µg/L Total Nitrogen as N 300 µg/L (ii) Parameter Density (Summer mean) - Benthic algal chlorophyll a 100 mg/square meter (Maximum) - Benthic algal chlorophyll a 150 mg/square meter (b) In the Clark Fork River from the confluence with the Blackfoot River (N46º52'19", W113º53'35") to the confluence with the Flathead River (N47º21'45", W114º46'43") the numeric water quality standards for Total Nitrogen, Total Phosphorus, and benthic algal chlorophyll a, applicable from June 21 to September 21, are as follows: (i) Parameter Concentration Total Phosphorus as P 39 µg/L Total Nitrogen as N 300 µg/L (ii) Parameter Density (Summer mean) - Benthic algal chlorophyll a 100 mg/square meter (Maximum) - Benthic algal chlorophyll a 150 mg/square meter