DISSOLVED OXYGEN 



TRINITY BAY 



UPPER GALVESTON BAY 



MID-GALVESTON BAY 



LOWER GALVESTON BAT 



reniPHERAL - 



OPEN WATER - 

 CHANNEL 



Figure 14. Mean concentrations of dissolved oxygen 

 by date and habitat within each bay area of the 

 Galveston Bay system, 1964-66. 



Comparison Between Bay Areas 



Comparisons of dissolved oxygen values be- 

 tween bay areas are shown in Table 12. In the 

 peripheral habitat, oxygen values were gen- 

 erally higher in mid-Galveston Bay than in the 

 other bays. In the channel, however, oxygen 

 values were lowest in Upper Galveston Bay and 

 increased toward Lower Galveston Bay. Dis- 

 solved oxygen concentrations, as shown by 

 mean values, were relatively stable throughout 

 the open-water habitat in 1964-65 but were 

 depressed in Upper Galveston Bay in 1966. 



Table 12.— Comparisons of annual mean concentrations 

 of dissolved oxygen (ml/liter) between bay areas 

 within each habitat in the Galveston Bay system, 

 1964-66. 



Comparison Between Years 



Seasonal trends in the concentrations of 

 oxygen were similar between years (Figure 15). 

 Oxygen values were maximum during the 



5 10- 

 5 5- 



I96< - 



1965 



[966- 



OPEN WATER 



10 20 K) 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 

 JAN FEB Mflfl APR MAY JUN JUL AUG SEP OCT NOV DEC 



Figure 15. Mean values of dissolved oxygen by date, 

 habitat, and year in the Galveston Bay system, 

 1964-66. 



winter, decreased through the spring and 

 attained an annual low in the summer. Oxygen 

 levels then increased during the fall and 

 attained an annual maximum again during the 

 following winter. This trend was inversely 

 correlated to temperatures as indicated by 

 r-values of -0.44, d.f. = 343 in 1964; -0.23, d.f. 

 = 686 in 1965; and -0.52, d.f. = 409 in 1966. 

 The channel habitat had greatest variations in 

 oxygen concentration between years. 



DISCUSSION 



Several major alterations that are expected 

 to affect the hydrography of the Galveston Bay 

 system are contemplated or under construc- 

 tion. An electric generating plant is being con- 

 structed on Cedar Bayou, which empties into 

 Upper Galveston Bay, by the Houston Lighting 

 and Power Company (Figure 1). A maximum 

 of about 63.7 m^/sec of water will be taken 

 into the intake canal located 14.5 km up Cedar 

 Bayou, warmed about 5° C, and discharged 

 into Trinity Bay through an excavated channel. 

 This amount of water flow is about 24% of the 

 average annual flow from the Trinity and San 

 Jacinto watersheds combined. The water being 

 drawn from Upper Galveston Bay through the 

 mouth of Cedar Bayou will flow predom- 

 inantly upstream. Passage of large volumes of 

 water through the generating plant is expected 

 to increase temperature, salinity, dissolved 

 organic nitrogen, and total phosphorus in some 

 areas of Trinity Bay. 



The proposed Texas Basin Project is one of 

 many plans to develop water resources of 

 Texas (Diener, 1964; Chapman, 1966). Reser- 

 voirs would supply water to a trans-Texas canal 

 which would intercept tributary discharge to 



11 



