flows inside sumps. The latter method requires a water 

 stage recorder float, an engineer's tape, and a stopwatch 

 (Figure 8) . 



ji0^- ~- 



•» . ,|| 



*f'i 



■j*^ 



FIGURE 8. "FLOAT METHOD" FLOW MEASUREMENT 



Other methods employed under certain conditions included a 

 velocity meter, the "V" notch weir, pump rating and meter 

 readings, a parshall flume, and other combinations. 



Nutrient Sampling . Samples were collected in plastic pint 

 bottles directly from tile outlets, sunqs pump discharge 

 pipelines (Figure 9), or from Inside the sump and stored in 

 ice chests to inhibit possible denitrification during 

 transport to the laboratory. 



Nutrient samples were collected on a weekly basis from all 

 the tile drainage systems included in the intensive investi- 

 gations (1966-68). Several "satellite" stations which were 

 located in the Byron-Westley and Gustine-Mendota areas were 

 sampled monthly during I968. Isolated tile systems were 

 ssunpled weekly for eight months in the same year. Prior to 

 1966, occasional samples were collected at random from 

 several stations. A definite sampling frequency was not 

 established until I966. 



35 



