280 



The Chalk Point nuclear power plant on the Patuxent River estuary 

 in Maryland has altered the temperature regime considerably. The 

 Contra Costa and Pittsburg, Calif., plants have created a new tem- 

 perature environment on the San Joaquin River in the delta area of 

 San Francisco Bay, Cooling water from Turkey Point plant in Bis- 

 cayne Bay, Fla., and the Morrow Bay plant in southern California 

 has created thermal structures that may be as high as 10°F above 

 ambient temperature. 



These examples represent only a few of the many thermal discharges 

 from power plants. Other industrial manufacturing processes utilize 

 considerable quantities of cooling water and may cause the same type 

 of environmental changes in addition to generating wastes. 



LAND USE AND RUNOFF 



Indiscriminate use of land areas contiguous to estuaries has resulted 

 in severe water quality problems (IV-5-10). There are many docu- 

 mented cases of pollution from land runoff. One of the most serious is 

 the tremendous impact created by the widespread application of in- 

 secticides to control fire ants in the southeast. The spraying programs 

 were apparently initiated without consideration of the potential un- 

 sought consequences, and the heavy toll of birds, fish, and other mam- 

 mals was phenomenal. 



Runoff from such uninhabited areas is not the only culprit. In 1968, 

 Endrin released in storm sewers found its way into Northeast Cape 

 Fear River in North Carolina. Thousands of fish, including many ana- 

 dromous species, were killed (IV-5-10) . 



Studies of the pollutional effect of storm runoff in Boston Harbor 

 have shown significant increases in deoxygenating substances, as well 

 as bacterial indicator organisms. Control of storm runoff is extremely 

 costly, but it is a very real part of pollution control. 



Runoff from phosphate mining areas in North Carolina and Florida 

 has added large quantities of nutrients to estuarine systems. The phos- 

 phate material combined with sewage and other nutrient sources forms 

 a unique, enriched aquatic environment with a real nuisance potential. 



STREAM FLOW REGULATIONS 



Stream flow regulation structures have been built on many of the 

 rivers directly tributary to estuarine systems. For the most part these 

 structures have had a beneficial influence on estuarine water quality. 

 The regulated stream flow provides a more uniform source of fresh 

 water with fairly constant quality which allows the estuarine system 

 to reach a dynamic equilibrium. In addition, the reservoirs act as set- 

 tling basins, reducing the sediment load in the estuaries. In a few cases 

 the flow regulation has so restricted the fresh water inflow that the 

 estuarine salinity structure has changed. 



Water quality changes resulting from the construction of flow regu- 

 lation structures are demonstrated in the following examples: 



(1) In the San Francisco Delta, upstream salinity intrusion is 

 controlled by releases from reservoirs on the Sacramento River. 

 Conversely, regulation of flow in the San Joaquin River is par- 

 tially responsible for recurring quality problems in the Stockton 

 area of the Delta ; and 



