long runs and pools (approximately mile 229 to mile 1^5); (3) the lower- 

 middle river, which consists of a dredged channel with levees (approxi- 

 mately mile l'4-5 to mile 19) J and (U) the lower river, which consists of 

 a broad tidal channel, sQ-so dredged and with levees. 



Upper Reach . Aquatic organisms collected from the river bottom 

 exhibited wide variations from reach to reach. Three representative sta- 

 tions were selected from each reach and the average nvunbers of organisms, 

 ajid genera, and average volumes per sqxisure foot for each reswh were deter- 

 mined. This information is presented in Figxure 15. 



Thirty-nine collections were made during the survey at the three 

 stations in the upper reach. Station locations were at mile 285. 9 > mile 

 275.0, and mile 229.8, all of which were located on riffle areas. The 

 average numbers of organisms, genera, and average volvmie of these samples 

 was much greater than that for any of the other reaches. Riffle areas 

 are generally considered to be more productive of aq.\iatic organisms than 

 pool areas. Dominant organisms in thiB reach were oligochaetes and insects. 

 Of the insects, the orders Plecoptera, Odonata, Ephemeroptera, Tricoptera, 

 and Diptera were the most iaiportant. Families of Diptera collected most 

 often were Tendipedidae , Tipulidae, and Simxaidae. 



I^per-Middle Reach . Thirty-three saioples were taken from sta- 

 tions in the upper-middle reach. These stations were located at mile 

 217.6, mile 199.6, and mile 168.2. All of these saaiples were taken from 

 pool areas near shore in water from 7 to 25 feet deep. No attempt was 

 made to sample organisms in the riffle areas of this reach. The nvunbers 

 of organisms collected were rather low, with few kinds present. The volume 

 of these organisms was extremely low, averaging only 0.2 cc. per square 

 foot of bottom saaipled. This wa^ only one-fourth to one-tenth the volume 



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