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Scientific Investigations Report 2007–5188

Prepared in cooperation with the National Park Service

Nutrient Enrichment in Estuaries from Discharge of Shallow Ground Water, Mt. Desert Island, Maine

By Charles W. Culbertson, Thomas G. Huntington, and James M. Caldwell

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Abstract

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park because of the potential problem of water-quality degradation and eutrophication in its estuaries. Water-quality degradation has been observed at the Park’s Bass Harbor Marsh estuary but not in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, but the importance of shallow ground water that may contain nutrients derived from domestic or other sources is unknown. Northeast Creek and Bass Harbor Marsh estuaries were studied to (1) identify shallow ground-water seeps, (2) assess the chemistry of the water discharged from selected seeps, and (3) assess the chemistry of ground water in shallow ground-water hyporheic zones. The hyporheic zone is defined here as the region beneath and lateral to a stream bed, where there is mixing of shallow ground water and surface water. This study also provides baseline chemical data for ground water in selected bedrock monitoring wells and domestic wells on Mt. Desert Island. Water samples were analyzed for concentrations of nutrients, wastewater compounds, dissolved organic carbon, pH, dissolved oxygen, temperature and specific conductance. Samples from bedrock monitoring wells also were analyzed for alkalinity, major cations and anions, and trace metals. Shallow ground-water seeps to Northeast Creek and Bass Harbor Marsh estuaries at Acadia National Park were identified and georeferenced using aerial infrared digital imagery. Monitoring included the deployment of continuously recording temperature and specific conductance sensors in the seep discharge zone to access marine or freshwater signatures related to tidal flooding, gradient-driven shallow ground-water flow, or shallow subsurface flow related to precipitation events.

Many potential shallow ground-water discharge zones were identified from aerial thermal imagery during flights in May and December 2003 in both estuaries. The occurrence of ground-water seeps was confirmed using continuous and discrete measurements of temperature and specific conductance in selected seeps and in the adjacent estuaries that showed salinity anomalies reflecting the input of freshwater in these complex tidal systems. Analysis of water samples from shallow ground water in the hyporheic zone and from ground-water seeps indicated the presence of elevated concentrations of dissolved nitrogen, compared to concentrations in the adjacent estuaries and surface-water tributaries draining into the estuaries. These findings indicate that shallow ground water is a source of dissolved nitrogen to the estuaries. Orthophosphate levels were low in ground water in the hyporheic zone in Bass Harbor Marsh, but somewhat higher in one hyporheic-zone well in Northeast Creek compared with the concentrations in both estuaries that were at or below detection limits. Household wastewater-related compounds were not detected in ground water in the hyporheic zone. Analysis of water samples from domestic and bedrock monitoring wells developed in fractured bedrock indicated that concentrations of dissolved nitrogen, phosphorus, and household wastewater-related compounds were typically at or below detection, suggesting that the aquifers sampled had not been contaminated from septic sources.

Contents

Figures

1–3. Maps showing—

1. Shaded-relief site locations of study areas that include Northeast Creek and Bass Harbor Marsh watersheds on Mt. Desert Island, Maine

2. Locations of water-quality sampling and continuous monitoring sites in the Northeast Creek watershed on Mt. Desert Island, Maine

3. Locations of water-quality sampling and continuous monitoring sites in the Bass Harbor Marsh watershed on Mt. Desert Island, Maine

4–5. Aerial photographs showing—

4. Thermal seeps identified using aerial infrared digital imaging in Northeast Creek watershed in December 2003

5. Thermal seeps identified using aerial infrared digital imaging in Bass Harbor Marsh watershed in December 2003

6–8. Graphs showing—

6. Precipitation, streamflow, specific conductance, and stage from July 20 through September 12, 2001. (A) Precipitation (rainfall) at McFarland Hill, Acadia National Park, Mt. Desert Island, Maine; (B) daily streamflow for the Narraguagus River near Cherryfield, Maine, plotted with specific conductance at station No. 104 in Northeast Creek; and (C) stage (tide) at station No. 101 in Northeast Creek, Maine

7. Seep water quality, precipitation, and ocean tide and water temperature for the period June through September 2004. (A) Temperature and specific conductance at 50 cm below sediment surface in seep 43a Bass Harbor Marsh; (B) rainfall at McFarland Hill, Acadia National Park, Mt. Desert Island, Maine; and (C) tide at Bar Harbor, Maine, and water temperature at 50 cm below sediment surface in seep 43a Bass Harbor Marsh

8. Total dissolved nitrogen in various waters

Tables

1. Constituent name, U.S. Geological Survey National Water Information System parameter codes, and minimum reporting limits for temperature, specific conductance, dissolved oxygen, pH, nutrients, and dissolved organic carbon

2. Constituent name, U.S. Geological Survey National Water Information System parameter codes, and minimum reporting limits for trace wastewater-related compounds (USGS water-quality analytical schedule 1433)

3. Constituent name, U.S. Geological Survey National Water Information System parameter codes, and minimum reporting limits for major ions and trace metals

4. Thermal anomalies identified during the flight on 5/28/2003 3:31–4:39. Municipalities included Bar Harbor, Southwest Harbor, and Tremont, Maine

5. Thermal anomalies identified during flight on 12/3/2003 23:45 to 12/4/2003 04:30. Municipalities included Bar Harbor, Southwest Harbor, and Tremont, Maine

6. Water quality in the hyporheic zone in wells in Northeast Creek

7. Water quality in the hyporheic zone in seeps in Bass Harbor Marsh

8. Water quality in Northeast Creek and Bass Harbor Marsh estuaries

9. Water quality in domestic wells

10. Water quality in bedrock monitoring wells

Suggested Citation

Culbertson, C.W., Huntington, T.G., and Caldwell, J.M., 2007, Nutrient enrichment in estuaries from discharge of shallow ground water, Mt. Desert Island, Maine: U.S. Geological Survey Scientific Investigations Report 2007–5188, 34 p. ONLINE ONLY


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For further information, contact:

Director
U.S. Geological Survey,
Maine Water Science Center
196 Whitten Road
Augusta, Maine 04330

dc_me@usgs.gov

or visit our Web site at:  http://me.water.usgs.gov/.

 

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