TABLE 45. (concluded) 



AGRIC ULTURA L AN D INDUSTRI AL WATER SUPPLY 



pH: 6.0-8.5 



6.5-8.5 for estuarine and salt waters 



Temperatures: 90 °F maximum (32.2 °C) 



5 °F maximum rise in streams, lakes, and reservoirs 



DO: 3.0 mg/1 



Turbidity: 50 Jackson units 

 INDUSTRIAL OPERATIONS 



Same as Agricultural and Industrial Water Supply 



NA VIGATION 



Same as Agricultural and Industrial Water Supply with the following 

 exception: 



DO: 2.0 mg/1 



near Mt. Vernon has a calcium-magnesium bicarbonate-type water at both low 

 and high flows (Table 48). Most other chemical constituents increase at low 

 flows (Ricco et al . 1973). 



The Mobile River is affected by saltwater intrusion from Mobile Bay, 

 occurring as a wedge of saltwater on the bottom of the river which, at times, 

 extends more than 20 mi upstream from the river mouth. The wedge occurs 

 because of the difference in temperature and densities of freshwater and 

 saltwater. The length and amount of the intrusion is influenced by stream 

 flow and tidal actions. At high tides and low stream flow the wedge is more 

 extensive and salinities are higher. At high stream flow or flood conditions 

 the wedge may be pushed out into Mobile Bay and the bay waters may become 

 more riverlike (Moser and Chermock 1978). Although most streams flowing into 

 saltwater bodies are affected by intrusion, as it is a naturally occurring 

 phenomenon, the navigation channel in the Mobile River increases the effect. 



The average and low-flow conditions of the Mobile River system will be 

 altered upon completion of the Tennessee-Tombigbee Waterway. Projections 

 indicate that with full development of the waterway, the average flow could 

 be increased as much as 1,560 ft 3 /s, with low flows increasing as much as 250 

 ft 3 /s (U.S. Army Corps of Engineers 1983). This could influence saltwater 

 intrusion in the Mobile River and may also affect salinities in the Mobile 

 River and in Mobile Bay. Apparently, the most probable effect would be to 

 lower salinities in both the river and the bay. 



159 



