milfoil) have choked out most other uses, including boat 

 traffic. 



The cause of excessive algae growths is primarily due to 

 the high concentrations of basic nutrients (nitrogen and 

 phosphorus) found in the Clark Fork-Pend Oreille system. 

 Despite this general knowledge, however, very little is known 

 regarding the sources or fate of nutrients in this aquatic 

 system. Nitrogen and phosphorus enter the water from the 

 basin's natural geologic strata, irrigation return flows, 

 animal wastes, domestic and industrial wastewater, and the 

 atmosphere. The relative contribution of nutrients from each 

 of these sources is generally unknown. 



Controls on nutrients to slow down or reduce eutrophi- 

 cation can be implemented by a variety of methods, including: 

 treating wastewater, limiting or banning the use of phos- 

 phates in certain products (e.g., detergents), reducing soil 

 erosion, putting voluntary restrictions on the use of lawn 'i- 

 fertilizers, placing and maintaining septic tanks properly, 

 treating urban stormwater runoff, and encouraging proper land 

 use activities. Many of these control efforts require strong 

 citizen support and voluntary participation; others require 

 relatively expensive treatment operations. 



A special program to investigate the sources and fate 

 of nutrients in the Clark Fork-Pend Oreille Basin was 

 initiated in 1988. The investigation is a coordinated 

 program funded under Section 525 of the Clean Water Act 

 Amendments of 1987. The states of Montana, Idaho, and 

 Washington, working in cooperation with the EPA, have 

 outlined a three-year assessment of nutrient-eutrophication 

 problems in the basin. The results of this investigation 

 are expected to provide a measure of the eutrophication 

 problem and sources of nutrients and to indicate appropriate 

 control measures. The continued close cooperation of the 

 three states is essential in meeting the program goals and 

 sustaining the required funding. The following is an 

 outline of the three-state program: 



1. Montana study objectives. 



a. Conduct a critical review of all available criteria 

 relating periphyton standing crop to beneficial 

 uses and factors regulating periphyton standing 

 crop in flowing waters. 



b. Determine the existing standing crop and nutrient 

 status of periphyton in the Clark Fork River 

 (seasonally) and relate data to existing criteria. 



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