The Effect of Timber Management 

 ON Stream Water Quality 



By F. Richard Hauer^ and Christopher O. Blum^ 



Introduction 



The primary purpose of this study was to 

 determine if past forest management practices 

 (logging and related roads) have affected stream- 

 water quality. Based on this primary purpose, 

 we established the following goals: 



(1) to evaluate techniques that would be 

 useful in examining the effects of for- 

 est management practices on stream 

 water quality, 



(2) to implement studies using those tech- 

 niques to evaluate water quality and 

 the conditions of streams affected by 

 forest practices, and 



(3) to establish a baseline from which a 

 longer monitoring plan might be de- 

 veloped. 



We defined stream- water quality as includ- 

 ing physical, chemical, and biological variables 

 of stream ecosystems, but did not include issues 

 specifically associated with fisheries manage- 

 ment. We founded the hypotheses of this study 

 on the concern that timber harvest and associ- 

 ated activities may result in increased sediment 

 and nutrient loading to streams. These physical 

 and chemical factors may, in turn, affect the 

 basic structure and function of the stream food 

 web through increased stream-algae produc- 

 tion and changes in stream invertebrates. 



Specific study objectives were to examine 

 streams in watersheds with different levels of 

 timber harvest and to determine if there have 



been measurable changes in: 



(a) sediment transport or nutrient concen- 

 trations, 



(b) the accumulation of attached algae ex- 

 pressed as surface density of Chloro- 

 phyll a and ash-free-dry-mass, and 



(c) the structure and function of the stream 

 invertebrate community. 



We chose 12 stream sites for study based on 

 differing levels of timber management, stream 

 size, and basin characteristics. Three study 

 stream sites had no timber harvest or road 

 building in the basin, five study sites were 

 identified as having low to moderate activity in 

 the drainage above the site, and four sites were 

 distinguished as having a high level of timber 

 harvest and roads in the watershed. Ideally, a 

 study designed to answer the question, "Do 

 current forest management practices affect 

 stream water quality?" would entail a water 

 sampling frequency of 15 to 20 times per year 

 and seasonal sampling for algal growth and 

 invertebrates over a 3 to 5 year period. How- 

 ever, we were limited in this study by both time 

 and financial resources. Nonetheless, we found 



'Dr. F. Richard Hauer is a Research Associ- 

 aieProfessor with the Flathead Lake Biological 

 Station in Poison, Montana. 



K!hristopher O. Blum is a Research Assistant 

 with the Flathead Lake Biological Station in Poison, 

 Montana. 



Flathead Basin Cooperative Program Final Report 



Page 43 



