THE SURVEYS 



Three separate surveys were made, during the 1948 periods July 

 6-16, August 16-20, emd September 7-9, During the first survey work 

 was done from a 23 foot diesel powered workboat supplied by the National 

 Park Service. Use of this boat, however, proved unduly time consuming 

 and the second two surveys were made by means of an outboard motor 

 powered skiff which was moved from place to place with an automobile 

 and trailer. Points at which data were taken and the dates upon 

 which they were visited were as follows j 



PHYSICAL CHARACTERISTICS 



At each station on the first two surveys the temperature, oxygen 

 content, free carbon dioxide, acidity, hydroxide, carbonate, bicar- 

 bonate, alkalinity, pH, and turbidity were measured. During the 

 third survey only temperature and tiarbidity were measured, as it was 

 felt that more time should be spent on gill netting. All of the 

 above variables except turbidity were measured at a number of 

 different depths, in order that their vertical distribution might 

 be ascertained. 



In interpreting the data presented in the tables, it should be 

 kept in mind that all of the stations were located near streams, so 

 that the characteristics of the water at the stations could be in- 

 fluenced to some extent by the inflowing stream water. An idea of 

 the influence upon lake water to be expected from streams emptying 

 near stations can be gained from the following list of percentages 

 of total flow through Roosevelt Lake: 



Stream 



Percentage of Total Flow 



San Poil River 

 Spokane River 

 Hall Creek 

 Colville River 

 Flat Creek 



0.2 

 7.1 



Less than 0.1 

 2.4 



Less than 0.1 



