Table 6. — Analysis of variance of four 3 by 3 

 Latin squares in Indian Creek study area 1. 



^Significant at the 1-percent level. 



II- 



\ 



<a 10- 



5 

 a 





8- 



7- 



6- 



5- 



:/ 



T 



5 



10 



— r 

 15 



20 



DEPTH IN GRAVEL IN INCHES 



Figure 5. --Decrease in 

 in streambed gravel, 

 Indian Creek. 1958. 



dissolved oxygen with depth 

 experiments 1, 2, and 3, 



Temperature data from the two 4 by 4 Latin 

 squares (table 8) show little variation in 

 ground- water temperatures with time or depth 

 in water table at the time of sampling. 



Tracing Ground-Water Seepage 



In Indian Creek, riffle ground water flows 

 from the bank into the streambed because of 

 a pressure gradient formed by the slope of 

 the water table (fig. 6). Ground water was 

 traced from the streambank into the stream- 

 bed by means of dye and through dissolved 

 oxygen and temperature differences. These 

 differences were first determined in 1956 

 through routine sampling of points throughout 

 the riffle. Figure 7 shows gradual increase 

 in dissolved oxygen content of water 10 inches 

 under the gravel with distance away from the 

 bank. 



In 1959 three sampling stations were in- 

 stalled (location shown as A in figure 2) to 

 obtain specific data on oxygen and temper- 

 ature differences. At the three stations, water 

 within the gravel was sampled at points 1 foot 

 apart extending from the bank 8 feet into the 

 stream. Measurements showed that at the time 

 of sampling (September) both temperature and 

 dissolved oxygen increased (fig. 8) with dis- 

 tance away from the ground-water source 

 until influence of ground-water seepage was no 



11 



