PRIMARY PRODUCTIVITY 



383 



INTAKE 



Fig. 1 Approximate bathometry of Lewis Creek Reservoir. Contour 

 lines show depth. 



formed by constructing an earthen dam over Lewis Creek, an 

 intermittent stream, has a maximum depth of 5.34 m, and its 

 elevation is 83 m. It is located in Montgomery County, Texas, at 

 latitude 30°26' and longitude 95° 32'. The climate is subtropical, 

 with mild winters, hot, humid summers, and a rainfall average of 120 

 cm/year. The drainage basin is ^^1000 ha, and the land is used 

 principally as pine timberland and livestock range. The area is 

 sparsely populated. 



Station 1 was located at the outfall of the canal, which discharges 

 into a small preliminary cooling pond ~1 km from the generating 

 plant. The temperature at Station 1 approximated the temperature 

 of the effluent as it left the plant. Station 2 was in a cove of the lake 

 ~2.5 km by water from Station 1. Because of the construction of a 

 dike, these two stations were separated by land by about 15 m. This 

 permitted almost simultaneous sampling and incubation. The 

 temperature of Station 2 approximated the temperature of the water 

 at the intake screen. 



METHODS 



Sampling 



Sample collections were made from September 1976 to August 

 1977. To minimize the errors inherent in sampling the heteroge- 

 neously distributed phytoplankton, we took one large water sample 

 from the surface to a depth of 30 cm at each station. Portions of the 

 large sample were used for chemical analysis, primary productivity 

 measurements, and phytoplankton cell counts. 



