Reports on all coastal towns west of Milbridge have been published. Reports 

 on all coastal towns east of Milbridge will be published in 1980. 



All major rivers and streams, great ponds, and tidal waters have been 

 classified according to their water quality status (Maine Department of 

 Environmental Protection 1977). The classification of coastal Maine surface 

 waters is presented in appendix B. 



Areas in coastal Maine with critical water quality problems have been 

 identified (U.S. Environmental Protection Agency 1978). Included are 15 

 sections of 13 rivers and estuaries in the characterization area (figure 3-1; 

 table 3-5). Critical water quality problem areas have such severe pollution 

 loading and/or minimal assimilative capacities that f ishable/swimmable water 

 quality will be below standard even after all point sources are under control. 

 The primary causes, either singly or in combination, for the critical water 

 quality problems remaining in coastal Maine are: combined sewer outflows (all 

 15 areas); municipal discharges (2 areas); industrial discharges (2 areas); 

 and low flow caused by flow regulation (1 area) . 



Other related factors are nonpoint source loadings (agricultural and urban 

 runoff) and toxic substances. The amount of information available on toxic 

 substances is limited. 



Water pollution has been traditionally, and continues to be, of concern in 

 coastal Maine. The ecological impacts of water pollution include bacterial 

 contamination of commercial clam flats, low dissolved oxygen, increased 

 turbidity, eutrophication, and temperature alteration in water bodies, and 

 pollution by oil, hazardous wastes, PCBs , and heavy metals. 



Bacterial pollution . Bacterial pollution has accounted for the closure 

 of 56% of the clam flats in the State of Maine. It has a severe economic 

 impact on the clam fishery and a potential effect on public health. However, 

 effects of bacterial contamination on clams, invertebrates, and other 

 organisms in the food chain are not evident (personal communication from P. F. 

 Larsen, Bigelow Laboratory for Ocean Sciences, Boothbay Harbor, ME; February, 

 1980). 



Dissolved oxygen . The utilization of organic wastes by microorganisms in 

 aquatic systems requires large amounts of oxygen (Clark 1977). An increase in 

 demand for oxygen because of organic wastes sometimes may lead to dangerously 

 low levels of oxygen in the sediments or in the water column above the 

 sediments (Clark 1977). If low levels of dissolved oxygen persist, most 

 animals die. Deoxygenated areas are recolonized by less desirable species 

 that are tolerant of low levels of oxygen (Grassle and Grassle 1974). 



Serious oxygen depletion in sediments is often caused by effluents from pulp 

 and paper mills. The floating components of the effluent prevent light from 

 reaching the phytoplankton and thereby reduce the amount of oxygen that is 

 produced photosynthetically . During summer the biodegradation of the pulp 

 fibers, sawdust, wood chips, and other organic wastes of the wood products 

 industry can deplete the dissolved oxygen in the sediment and in the deeper 

 layer of the water column (Poole et al. 1977), adversely affecting fish, 

 invertebrates, and other aquatic organisms. 



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10-80 



