quality in Escambia River and in Escambia Bay is relatively high. The river 

 runs through the major Pensacola urban area and part of it adjoins the Pensa- 

 cola Naval Air Station. In 1977-79, several water quality violations were 

 reported for total alkalinity, cadmium, lead, pH, DO, and copper. The recent 

 trends show some improvement. 



Perdido River Basin . The Perdido River flows south from the Alabama line 

 approximately 62 miles and empties into the Perdido Bay. Water quality in the 

 river is relatively good. A comparison of historic and recent water quality 

 data suggests a trend towards improvement in DO and nitrate-nitrite concentra- 

 tions. Total phosphorus also has decreased in the lower reaches of the 

 Perdido River. An apparent decrease in mean pH value throughout the river may 

 be related to hydrologic conditions within the last two years. In 1977-79, 

 several violations involving pH, DO, total alkalinity, and several metals were 

 reported. These violations do not appear to be frequent enough for serious 

 concern. 



LIKELY FUTURE TRENDS 



Section V of water quality assessment papers entitled "Statistical 

 analysis of water quality vs. point and nonpoint pollution sources" is an 

 exercise in multiple regression analysis where pollution point and nonpoint 

 sources are statistically regressed against specific water quality criteria 

 (Florida State Department of Environmental Regulation 1979a). Correlation 

 coefficients were calculated between pairs of water quality parameters and 

 pollution loading factors. The signs from the coefficients indicate whether 

 or not they are positively or negatively related and are instructive for both 

 current analysis of pollution loadings and levels, and future forecasts. 

 Correlation coefficients were reported for variable pairs with statistically 

 significant relationships at a 95% confidence level. 



The analysis suggests that a better relationship exists between water 

 quality (WQI) and watershed characteristics than one would expect. A corre- 

 lation coefficient of 0.74 indicates that point source, nonpoint source, and 

 urban centers tend to be correlated with lower water quality. The PNS water- 

 shed, which has highly concentrated pollution sources, and a low watershed 

 index (WSI), has lower water quality, and lower WQI. The degree of scatter in 

 the plot indicates that not all of the WQI is explained by watershed charac- 

 teristics alone (Figure 1). This is reasonable given the multiple casual 

 relationships involved. 



The report also develops a water quality index and a WSI that demon- 

 strates the relationships among changes in standard values of all examined 

 water quality parameters as a function of land use within the watershed area. 

 The WSI is a value reflecting the flow of point and nonpoint sources within 

 the watershed both in terms of chemical concentrations and volume flow. The 

 general relationship established between water quality and watershed pollution 

 sources was examined through a plot of WQI and WSI values (Figure 1). High 

 values of total phosphorus were associated with population centers and areas 

 of intense industrial activities such as strip-mining and industry. Forested 

 areas retain considerably more phosphorus than rangeland. PNS watersheds with 

 waters highly polluted with municipal wastes also show levels of phosphorus. 



252 



