Thompson (1978) has collected temperature and salinity data since 1969 in 

 conjunction with the installation of the Cowseagan Narrows Causeway and the 

 Maine Yankee Atomic Power Company plant. These data do not facilitate 

 identification of potential effects of the power plant and causeway on 

 estuarine hydrography, since they were collected during low and high river 

 runoff, which could obscure any other effects. 



Damariscotta River estuary . Although the Damariscotta estuary is narrow 

 and relatively shallow in comparison to the Kennebec estuary, its flow regime 

 is quite different, because of its very low fresh water inflow. This appears 

 in the Ketchum flushing model results, which indicate long flushing times, 

 generally low nontidal flow, and high salinity throughout most of its length 

 (figure 5-18). Tidal currents are not as strong as in the Kennebec, so that 

 some thermal stratification can be expected in the summer due to the long 

 residence time of marine waters in the estuary. Nontidal velocities are very 

 low. The model represents mean flow and it should be noted that under high 

 flow the increased fresh water discharge could modify the salinity regime and 

 flushing characteristics substantially. Most of the hydrographic data for 

 this estuary are contained in a report by McAlice (1977) and some additional 

 data are contained in Hulburt (1968). The following synopsis is taken largely 

 from the former. 



The Damariscotta estuary is an embayment with a small fresh water flow 

 entering from Damariscotta Lake via Salt Bay. The estuary is stratified near 

 the head but approaches well-mixed conditions towards the mouth, with some 

 stratification in both temperature and salinity present over most of the year. 

 The temperature stratification is maximal in summer, with warmer water towards 

 the head and surface, but is weak and reverses itself in winter, with cooler 

 water at the head. 



Strong vertical mixing occurs in the floodtide waters upstream of the Fort 

 Island and Fitch Point constrictions. The flow is two-layered. The tide 

 enters progressively and is 18 minutes later at the head than at East 

 Boothbay. The basins between the constrictions at Fitch Point, Fort Island, 

 and the head tend to fill sequentially; the ebb is similarly 24 minutes later 

 there than that at East Boothbay. Drifter studies have revealed that tidal 

 currents are basically longitudinal, with local variations. The ebb is 

 constrained to the channel, while the more diffuse flood is less so, but local 

 eddies are present in the ebb south of the Newcastle bridge. Hall Point, Merry 

 Island, and Wentworth Point. The estuary is partially mixed above Wentworth 

 Point and approaches well-mixed conditions south of that point. 



Penobscot River estuary . The boundaries of the Penobscot estuary are 

 difficult to define. The upper limit of salt water varies seasonally between 

 2 miles (3.2 km) south of the Bangor Dam (Bangor-Hampden region) and 9 to 11 

 miles (14 to 18 km) south of the dam (almost to Winterport; Haefner 1967). 

 The downstream oceanic limit is similarly difficult to define, as the estuary 

 widens gradually from Sandy Point and divides into two channels at North 

 Haven. In terms of salinity, 30 ppt water occurs at the surface as far up as 

 Sears Island and 31.9 ppt at the mouth of the bay (Seiwell 1932). For the 

 purposes of the model, the upper boundary was set at 8 miles (13 km) below the 

 dam and the lower boundary at a line connecting Rockport, North Haven, and 

 Stonington. 



5-30 



