Since drainage rehabilitation is new, a number of questions were 

 determined which need to be answered through research in order that 

 an adequate and economical rehabilitation may be done. These are: 



1. Through laboratory research, practical field chemical tech- 

 niques must be developed for measuring quickly the concen- 

 trations of toxicants in flowing water. 



2. Hydraulic studies must be made both in laboratories and in 

 streams to show the pattern of toxicant dispersion and dilution 

 as applied toxicant travels down a stream course. 



3. Laboratory studies must be made to establish concentrations 

 of toxicant and duration of exposure to these concentrations 

 necessary to kill the various species of fish under various con- 

 ditions of water quality and temperature. 



4. Field tests must be made to determine concentrations of applied 

 toxicants as well as optimum frequency of application and 

 method of application. 



5. Studies of the effects of various toxicants upon fish food 

 organisms in streams must be conducted to determine the time 

 which must be allowed after toxicant application before fish 

 may be reintroduced. 



-^Sm^ 



-TtJ' 



4 



^ra^" 



— ;t^-^- ,.- 



^:^^^^f-^r^ 



m'^^S^SS 



Fislieries crew introduces the sacks of toxicant used to clean out tlie fish population in the Marias 

 drainase. Nearly 1,000 miles of streams were treated in this manner to reclaim trout waters. 



FISHING PRESSURE ON NILAN RESERVOIR 



To manage a fishery properh', the Department must have informa- 

 tion concerning fisherman-use and harvest. Economical methods of 

 determining this must be developed. Such a method was tested at" 

 600-acre Nilan Reservoir in the Augusta area in 1954. Not only is the 

 adaptability of this method of interest, but tlie results obtained are 

 of even more interest. The lieavy fisherman-use made of this reservoir 

 demonstrates the importance of recreational fishing to the economy of 

 Montana and to the social well-being of its people. 



— 55 — 



