• Sampling is easy and inexpensive, and causes minimal impact 

 to resident biota and their habitat; 



• Standard methods and criteria exist for evaluating the 

 composition, structure, and biomass of algal associations,- 

 and 



• Excess algae in streams is often perceived as a problem by 

 the public. 



It is an objective of the federal Clean Water Act, and of 

 the USEPA and state agencies that implement the Act, to "restore 

 and maintain the chemical, physical, and biological integrity 

 of the Nation's waters" (Section 101). In response to this 

 directive, the State of Montana has developed methods and 

 criteria for evaluating various levels of biological integrity 

 and use impairment in Montana streams (Bahls 1993, Bukantis 

 1998) . Biological integrity is defined as "the ability of an 

 aquatic ecosystem to support and maintain a balanced, integrated, 

 adaptive community of organisms having a species composition, 

 diversity, and functional organization comparable to that of the 

 natural habitats within a region" (Karr and Dudley 1981) . 



The Clean Water Act further directs states to develop 

 pollution control plans (Total Maximum Daily Loads or TMDLs) that 

 set limits on pollution loading to water-quality limited 

 waterbodies . Water-quality limited waters are lakes and stream 

 segments that do not meet state water quality standards, that is, 

 do not fully support their beneficial uses. The Clean Water Act 

 and EPA regulations require each state to (1) identify waters 

 that are water-quality limited, (2) prioritize and target waters 

 for TMDLs, and (3) develop TMDL plans to attain and maintain 

 water quality standards for all water-quality limited waters 

 (MDEQ 1998) . 



