EXTREME HIGH WATER SPRING 



MEAN HIGH WATER 



EXTREME MEAN 



SPRING TIDAL TIDAL 



RANGE RANGE 

 (largest tidal range; 



EXTREME HIGH WATER NEAP 



EXTREME 

 NEAP TIDAL" 

 RANGE *r" 



(least tidal range) 



MEAN TIDAL LEVEL 



EXTREME LOW WATER NEAP 



MEAN LOW WATER 



EXTREME LOW 



WATER SPRING 



Figure 4-7. Tidal levels and ranges. 



Daily predictions of the tide are published annually by the U.S. Department of 

 Commerce in "Tide Tables, High and Low Water Predictions." Deviations in 

 tidal predictions occur during storms with the associated winds. 



Processes influencing coastal water . Besides being influenced by 

 atmospheric temperature, temperature and salinity are affected by river 

 discharge, indrafts of offshore waters (upwelling), storms, and currents. 

 Water masses are moved by currents and upwelling. Tides are affected by 

 storms. These dynamic processes are discussed below. 



The discharge of fresh water via rivers and estuaries affects the salinity and 

 temperature of marine waters in the coastal zone. Thirteen rivers in the 

 characterization area have gaging stations where flow is recorded (see table 

 6-3 in chapter 6, page 6-7). Analysis of the effects of river discharge from 

 the Penobscot, Sheepscot, and Kennebec-Androscoggin rivers on Boothbay Harbor 

 nearshore marine waters revealed (through salinity distribution) that 

 Penobscot River water traveling westward was the most likely major source of 

 freshened water observed in Boothbay Harbor (figure 4-8). Discharge from the 

 Sheepscot and Kennebec is carried to the west, away from the Boothbay region. 

 Graham (1970a) calculated an average westward nontidal drift of 1.87 miles/day 

 (0.07 miles/hour; 3 km/day; 0.12 km/hour) for coastal water between Bucksport 

 and Boothbay Harbor. (The movement of riverine discharge in other rivers and 

 streams in coastal Maine is not well known.) 



4-20 



