of the main stream channel also usually 

 approximated dissolved oxygen levels of the 

 flowing stream, except in areas underground- 

 water influence and during low stream levels 

 when interchange was minimized. 



On the other hand, within the gravel of the 

 bar, both temperature and dissolved oxygen 

 content of water varied widely depending on 

 stream level. The bar was covered with water 

 on high stream levels (the bar became a part 

 of the main stream channel at a stream gage 

 reading of 2.20 or more) and uncovered on 

 low stream levels (stream gage reading of 

 1.90 or less). Dissolved oxygen content of water 

 in the gravel of the bar increased with an in- 

 crease in stream level. This is shown in 

 figure 9. The shapes of the curves representing 

 the increase of dissolved oxygen with stream 

 level at individual standpipes differ because 

 (1) some of the standpipes were located at 

 points where the gravels were more permeable, 

 hence more interchange occurred, (2) some of 



1.0 



.5 2.0 



GAGE HEIGHT IN FEET 



Figure 9. --Increase in dissolved oxygen levels of 

 water in the gravel bar with increase in stream 

 water levels, Indian Creek, August 1958. (Numbers 

 correspond to standpipe locations shown in figure 2. 

 Relative depths of pipes shown in figure 3.) 



the curves represent points closer to ground- 

 water outflows, and (3) standpipes were not 

 all at the same depth below the water table. 



When stream level was above 2.2 feet and 

 stream water ran over the bar, there was a 

 fairly good relationship between temperature 

 and dissolved oxygen (upper fig. 10). 



At a lower stream level sampling points 

 showed a different temperature-dissolved oxy- 

 gen relationship (lower fig. 10). First, dis- 

 solved oxygen levels were generally lower 

 than they were on a higher stream level. 

 Second, although dissolved oxygen and tem- 

 perature at points 3, 43, 6, and 66 have re- 

 mained generally low, the water at points 

 which were previously high in dissolved oxy- 

 gen (64, 29, 9, 2, 20, 30, 67, and 63) shows 

 a marked decrease in dissolved oxygen con- 

 tent, but either remains the same or in- 

 creases in temperature. 



8/20/58 

 Gage height 2.4' 



© © 



© 



® 



8/22/58 

 Goge height 1.9' 



® 



© 



(3) 



© 



e 



© 



© 



© © 



® 



50 57 52 53 54 55 56 57 58 59 

 TEMPERATURE IN m f 



Figure 10.- -Dissolved oxygen levels plotted against 

 water temperatures on two different gage heights, 

 Indian Creek, August 1958. (Numbers correspond 

 to standpipe locations shown in figure 2. Relative 

 depths of pipes shown in figure 3.) 



16 



