Bibliography Background About KRIS

Water Quality in Gulf of Maine Atlantic Salmon DPS Watersheds


As noted in the Nutrients section, elevated pH can be a concern in rivers that are nutrient enriched, but low pH or acid conditions are a more widespread threat to the health of Atlantic salmon in the DPS Gulf of Maine rivers (Dill et al., 2002; NRC, 2004). Dill et al. (2002) note that "There are episodic declines in pH and increases in aluminum in Maine rivers that are sufficient to adversely affect sensitive life stages of salmon." Exposure to levels of pH under 6.2 is harmful to Atlantic salmon (Kroglund and Staurnes, 1999). Sensitive life history phases include the egg and alevin phase, fry at swim up and onset of feeding, and the smolt phase (Dill et al., 2002).

Smolts may be the most vulnerable because of the challenge posed by transition to salt water. The National Research Council (2004) specifically noted effects on smolts from acid rain as one of the most significant factors limiting Atlantic salmon recovery. "The problem of early mortality as smolts transition from freshwater to the ocean and take up residence as post-smolts needs to be solved" (NRC, 2004). Alkalinity is a useful measurement in judging risk from acid rain because it is an index of a streams buffering capacity (Whiting, 2002).

Whiting (2002) noted that "pH and alkalinity (or Acid Neutralizing Capacity, ANC) were moderate (pH range 5.72-8.23, ANC range 25-2,350 ueq/L) and within ranges known to be healthy for Atlantic salmon and other aquatic life. There was no evidence of chronic acidification or extreme nutrient or organic loading." Arter (2004) noted that, although the Sheepscot River did not normally have pH values that pose a threat to Atlantic salmon, the lowest value of 5.7 was registered during high flows such as winter storm events or spring runoff. Several studies have shown patterns of pH problems in Atlantic salmon DPS rivers (Haines and Akielaszek, 1984; Haines et al., 1990; Beland et al., 1995; Whiting, 2002; Arter, 2004). River systems east of the Penobscot have soil and geologic conditions which make them more vulnerable to acid precipitation and runoff (Table 4). "The rivers most vulnerable to acidification are: Narraguagus, Pleasant, Machias, East Machias, and Dennys" (Dill et al., 2002). Tributary basins seem to be more vulnerable than mainstem rivers and the Pleasant River registered the lowest values.

Table 4. Minimum pH levels for various DPS Atlantic salmon rivers from various studies.

Stream Minimum pH Level Study
Narraguagus/Machias <5-6 Haines and Akielaszek (1984) 
Narraguagus River 5 Haines et al. (1990) 
Narraguagus (Mainstem) 5.6-5.7 Beland et al. (1995) 
Narraguagus (Tributaries) 4.3 Beland et al. (1995) 
Pleasant River 4.1 Beland et al. (1995) 
Pleasant River 5.2 Whiting (2002)
Tunk Stream 4.7 Whiting (2002)
Sheepscot River 6.32 Arter (2004) from ASC data
Sheepscot River  6.0 Arter (2004) from NOAA data


There are records of fish mortality and studies indicating levels of impairment of Atlantic salmon in DPS rivers due to acid precipitation and runoff. Haines et al. (1990) found mortality of pre-smolts in the winter of 1986-87 in Sinclair Brook, a tributary of the Narraguagus. While the Tunk Stream is not a listed DPS river, Whiting (2002) documented mortality of alewives in conjunction with two storm events in October and November 2002: "The cause of death was asphyxiation and is consistent with acid rain toxicity." Magee et al. (2001) showed that river-resident smolts from the Narraguagus River delayed emigration and had inferior osmoregulatory function, when compared to hatchery-reared smolts. Dill et al. (2002) noted that this could indicate inhibition of successful smolting and recommended more studies.

A potential contributor to acid conditions in streams may come from blueberry and cranberry production: "Application of elemental sulfur to low bush blueberry fields to reduce soil produce a soil pH of 4.2" (Dill et al., 2002). 

See the general KRIS background page for more information about pH, Alkalinity and Conductivity


Arter, B. S., 2004. Sheepscot River Water Quality Monitoring Strategic Plan: A guide for coordinated water quality monitoring efforts in an Atlantic salmon watershed in Maine. Prepared for the Project SHARE: Research and Management Committee. 84 pp. [975kb]

Beland, K., N. Dubé, M. Evers, R. Spencer, S. Thomas, G. Vander Haegen, and E. Baum.1995. Atlantic salmon research addressing issues of concern to the National Marine Fisheries Service and Atlantic Sea Run Salmon Commission. Maine Atlantic Sea Run Salmon Commission Final Project Report NA29FL0131-01.

Chizmas, J. S. 1999. Study of pesticide levels in seven Maine rivers. Maine Board of Pesticides Control. 14 pp [6.2 Mb]

Dill, R., C. Fay, M. Gallagher, D. Kircheis, S. Mierzykowski, M. Whiting, and T. Haines. 2002, Water quality issues as potential limiting factors affecting juvenile Atlantic salmon life stages in Maine rivers. Report to Maine Atlantic Salmon Technical Advisory Committee by the Ad Hoc Committee on Water Quality. Atlantic Salmon Commission. Bangor, ME. 28 pp. [162kb]

Goldman, C.R. and A.J. Horne. 1983. Limnology. McGraw-Hill, Inc. New York . 464 pp.

Halsted, M., 2002. Effects of stream flow on the stream temperature, E. coli concentrations and dissolved oxygen levels in the West Branch of the Sheepscot River. Alna, ME. 15 pp. [450kb]

Haines, T., and J. Akielaszek. 1984. Effects of acidic precipitation on Atlantic salmon rivers in New England. U.S. Fish and Wildlife Service FWS/OBS-80/40.18.

Haines, T., S. Norton, J. Kahl, C. Fay, S. Pauwels, and C. Jagoe. 1990. Intensive studies of stream fish populations in Maine. U.S. Environmental Protection Agency, Office of Acid Deposition, Environmental Monitoring and Quality Assurance, EPA/600/3-90/043.

Kroglund, F., and M. Staurnes. 1999. Water quality requirements of smolting Atlantic salmon (Salmo salar) in limed acid rivers. Can. J. Fish. Aquat. Sci. 56: 2078-2086.

Magee, J. 2001. Agrochemical monitoring and potential effects on Atlantic salmon in eastern Maine rivers. National Marine Fisheries Service Report.

Maine Department of Agriculture. 2002. Report on activities in Atlantic Salmon Conservation Plan Rivers 2002. Maine Dept. of Ag. 

Maine Department of Environmental Protection. 2002. Water quality concerns and effects from state fish hatchery discharges. Unpublished Report. Augusta, ME.

Maine Department of Environmental Protection. 2004. 2002 Section 303(d) Report: Total Maximum Daily Load (TMDL) Waters. Augusta, ME.

National Research Council, 2003. Atlantic Salmon in Maine. The Committee on Atlantic Salmon in Maine, Board on Environmental Studies and Toxicology, Ocean Studies Board, Division on Earth and Life Sciences. National Research Council of the National Academies. National Academy Press. Washington, D.C. 260 pp. [3.5Mb]**

Pugh, L., 2002. Analysis summary of water quality monitoring data, 1994-2001. Sheepscot Valley Conservation Association . Alna, ME. 6 pp. [225kb]

Robinson, K. W., J. P. Campbell, and N. A. Jaworski, 2003. Water quality trends in New England rivers during the 20th century. United States Geologic Service. Water-Resources Investigations Report 03-4012. Pembroke, NH. 29 pp. [950kb]

State of Maine. (1998). Maine Section 303(d) Waters list.

U.S. Environmental Protection Agency, 1986. Quality criteria for water 1986: EPA 440/5-86-001. Office of Water Regulations and Standards,  Washington D.C.

U.S. Fish and Wildlife Service and National Oceanic and Atmospheric Administration, 2000. Endangered and Threatened Species; Final Endangered Status for a Distinct Population Segment of Anadromous Atlantic Salmon (Salmo salar) in the Gulf of Maine. Federal Register Notice Vol. 65, No. 223 / Friday, November 17, 2000 / Rules and Regulations. Pages 69459-69483 [225kb]

Whiting, M., 2001a. Year 2000 Progress Report for DEP Water Quality Monitoring Plan - Maine Atlantic salmon rivers. Maine DEP, Bangor Regional Office. Bangor, ME. 4 pp. [25kb]

Whiting, M., 2001b. Progress report: A summary of water quality monitoring results from Spring 2001, Maine Atlantic Salmon Rivers Project. Maine DEP, Bangor Regional Office. Bangor, ME. 6 pp. [775kb]**

Whiting, M., 2002. Maine Salmon rivers water quality monitoring progress report for 2002 field season. Maine DEP, Bangor Regional Office. Bangor, ME. 22 pp. [2.25Mb]**

Williams, S. 2002. Maine Volunteer Lake Monitoring Program Annual Report 2002. Maine Volunteer Lake Monitoring Program, Auburn, Maine. 52pp. [7 Mb]

Williams, S. 2003. Maine Volunteer Lake Monitoring Program Annual Report 2002. Maine Volunteer Lake Monitoring Program, Auburn, Maine. 52 pp. [8 Mb]