Data Analysis 



Estuary Segmentation 



Concentration 



of 



Chemical 



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Figure 3.3 Estuary segmentation permits reducing the variability 

 from hundreds of data points to a simplified picture of 

 estuary trends. 



In addition to providing a means for summarizing data for geo- 

 graphic stretches of the estuary, segmentation is important for the 

 development of water quality models and the subsequent allocation 

 of waste discharges into the estuary. Future management actions 

 will most likely set pollution load reduction goals segment by 

 segment. The impact of this scheme on the affected dischargers 

 may be significant. Therefore, a segmentation scheme will need to 

 consider political boundaries and the locations of the dischargers, 

 as well as physical features and hydrography of the estuary. 



Once the data are screened, they can be analyzed by scientists to 

 answer specific questions about the relationships among pollu- 

 tants, pollutant loadings, and their effects on water, sediment, and 

 living resources. The general objectives of these analyses are to: 



• Determine the temporal trends and spatial patterns related to 

 the most pressing problems of each estuary; 



• Determine possible causes of these problems; 



• Provide an integrated description of the conditions encountered 

 in each estuary; and 



• Identify significant, missing data that warrant additional monitor- 

 ing or sampling. 



The identification of temporal trends — or changes over time — is 

 important for recognizing problems and suggesting potential 

 causes. The landings of a particular species of fish in an estuary, 

 for example, may continuously decline over a 40-year period 

 (Figure 3.4). This trend suggests that the species may be adversely 

 affected within the estuary, but it does not suggest the potential 

 cause. Nevertheless, the temporal trend of interrelated, suspected 

 causes, such as overfishing, pollution, or habitat loss, can be 

 compared with the overall trend in fish landings. If there are 



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