Quality Assurance. Several steps were taken to assure that 

 the study results are accurate and reproducible. Upon receipt of 

 the samples, station and sample information were recorded in a 

 laboratory notebook and samples were assigned a unique number 

 compatible with the Montana Diatom Database, e.g., 1819-01. The 

 first part of this number (1819) designates the sampling site 

 (Big Spring Creek above Casino Creek at Brewery Flats); the 

 second part of the number (01) designates the number of 

 periphyton samples that have been collected at this site to date 

 for which data have been entered into the Montana Diatom 

 Database . 



Sample observations and analyses of soft (non-diatom) algae 

 were recorded in a lab notebook along with station and sample 

 information provided by MDEQ . A portion of the raw sample was 

 used to make duplicate diatom slides. 



On completion of the project, station information, sample 

 information, and diatom proportional count data will be entered 

 into the Montana Diatom Database. One set of diatom slides will 

 be deposited in the University of Montana Herbarium in Missoula. 

 The other set of slides will be retained by ifaxmaea in Helena. 



RESULTS AND DISCUSSION 



Results are presented in Tables 4, 5 and 6, located near the 

 end of this report following the Literature Cited section. 

 Spreadsheets containing completed diatom proportional counts, 

 with species pollution tolerance classes (PTC) and calculated 

 percent abundances, are attached as Appendix A. 



SAMPLE NOTES 



Big Spring Creek a±»ove Casino Creek (2) . This sample was 

 partly decomposed and smelled of hydrogen sulfide when opened on 

 August 6. The bulk of this sample was sand and gravel. About 

 10% of the diatom cells were empty. 



Casino Creek at Public Bridge (4) . The bulk of this sample 

 consisted of clumps of organic floe held together by a matrix of 

 fungal hyphae . The sample was preserved with formalin. The 

 Cladophora in this sample was also covered with organic floe. 

 About 10% of the diatom cells were empty. The Closterium in this 

 sample was smaller than the one in Big Spring Creek upstream and 

 was probably a different species. 



