c. Conduct an on-site study at selected locations to 

 determine factors (e.g., sediments, nutrients, 

 temperature, substrate, metals, macroinvertebrates) 

 limiting periphyton growth and standing crop in 

 the Clark Fork. 



d. Identify primary nutrient sources and establish 

 appropriate criteria for controlling periphyton 

 growth in the Clark Fork Basin. 



2. Idaho study objectives. 



a. Develop a nutrient budget for Lake Pend Oreille, 

 including point and nonpoint sources. 



b. Assess nutrient levels and/or reductions necessary 

 to protect lake water quality. 



c. Provide a final report in the Clean Lakes Phase I 

 Diagnostic Study format. 



3. Washington study objectives. 



a. Evaluate the trophic conditions within the Pend 

 Oreille River system, including identification of 

 limiting nutrients and characterization of current 

 trophic status. 



b. Develop a seasonal and annual nutrient and water 

 budget for the reach from Albeni Falls Dam to Box 

 Canyon Dam (RM 90 to RM 34) . 



c. Characterize external loading sources to the Pend 

 Oreille River, including comparison of local tribu- 

 taries, nonpoint, and point sources. 



d. Evaluate potential internal loading of nutrients 

 from macrophytes and sediments. 



In addition to the Montana objectives listed above, the 

 following are recommendations for nutrient-related issues in 

 the Clark Fork. 



1. Determine the effects of the Phosphoria Formation and 

 phosphorus mining on water quality. 



Determine the phosphorus load derived from the Phos- 

 phoria Formation, a geologic strata rich in phosphorus 

 near Garrison, or from past and present phosphorus 

 mining in the area. The investigation should begin with 



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