Water Quality

Contact • Background • Current Research

STEERING COMMITTEE CONTACT:

• David Courtemanch, Maine DEP

BACKGROUND

• Water Quality/Chemistry
• Pollution

Penobscot River Water Quality

Water chemistry in the Penobscot is influenced by geology, atmospheric inputs, land cover, and land use (Kahl et al., 1991) in a huge watershed that drains more than one-quarter of the entire state. The Penobscot River is pH-neutral, moderately buffered, and relatively oligotrophic compared to other major rivers in eastern North America (Jackson et al., 2005). However, recent studies by the Maine Department of Environmental Protection and Penobscot Nation suggest that biological oxygen demand, nutrients, and chlorophyll-a levels in the mainstem of the river may be approaching a more eutrophic state (Mitnik, 2002; 2003).

Water quality characteristics of the mainstem Penobscot River

Acidity (pH)
The Penobscot River is well-buffered (ANC=218 ueq/L ) and near-neutral (average field pH 6.8). Geographically, the Penobscot River is at the boundary between the well-buffered, relatively clear water systems of west-central Maine and the acidic, highly colored surface waters of eastern Maine, a result of different hydrology and relative abundance of wetlands. Western tributaries Marsh Stream, Cove Brook, and Kenduskeag Stream all have an average pH above 7 (Johnson and Kahl, 2005).

Dissolved oxygen
Maine DEP and the Penobscot Indian Nation Natural Resources Department measure dissolved oxygen at sample locations on the West Branch and mainstem. Dissolved oxygen requirements are defined by the water classification assignment made to a waterbody (Class AA/A and B requires >7ppm and 75% saturation; Class C requires >5ppm and 60% saturation, with 30-day average of 6.5 ppm). The East Branch is Class AA, West Branch below Millinocket is Class C, the mainstem is Class C from the confluence with the East Branch to the Mattawamkeag River, mainstem below the Mattawamkeag is Class B to the estuary. The Penobscot attains its dissolved oxygen criteria, except that portion from Winn to the Milford Dam (48 miles) is estimated to not attain class B minimum dissolved oxygen criteria during periods of low flow and high temperature (Mitnik, 2002; Figure 1. PDF document).

Dissolved organic carbon (DOC)
Dissolved organic carbon comes from wetlands, leaf litter, and overland runoff, as well as from degradation of organic matter within the river. Waste water discharges to the river also contribute significant amounts of DOC. Large amounts of DOC can stain water tea-colored. Rivers east of the Penobscot and those draining wetland areas have more DOC/color. Average DOC in the mainstem of the Penobscot is 8.3 ppm, which is within the typical range for other large lowland Maine rivers (J.S. Kahl, unpublished data). DOC export (average annual DOC export = 5.7 t/km²/year) tends to be lowest in July and August and increases to moderately high levels during the fall, intermediate in winter, and peaks during spring snowmelt (Hunting and Aiken, 2005).

Nutrients (nitrogen and phosphorus)
Total nitrogen in the Penobscot ranges from 0.2 to 0.4 ppm (Mitnik, 2002). Nitrogen is a limiting nutrient in marine environments, so nitrogen flux to coastal waters is a potential concern. Sources of nitrogen include municipal wastewater treatment plants, pulp and paper mills, stormwater runoff, septic systems, agriculture, and atmospheric deposition.

Phosphorus is a limiting nutrient in freshwater. Average total phosphorus below the Milford Dam is 25 ppb (J.S. Kahl, unpublished data). DEP measured average total phosphorus levels below point-source discharges between 20 and 30 ppb. In the estuary, phosphorus levels increased in the seaward direction to 40 and 50 ppb. Levels of phosphorus measured in tributaries ranged from 7 to 22 ppb (Mitnik, 2002).

Chlorophyll-a
Elevated chlorophyll-a levels indicating algae blooms (8 to 13 ppb) have been detected above Dolby, Rockabema and Weldon Dams and in the estuary near Orrington (Mitnik, 2002). Mitnik (2002) concluded that "eutrophication on the Penobscot, although not severe, could be approaching levels of concern and may prove to be an issue in the future." In 2004, the Penobscot Nation tracked a massive algae bloom that originated at Dolby Pond and stretched the entire length of the river, presumed to be caused by phosphorus discharge in Millinocket.

*Steve Kahl, Ken Johnson, and David Courtemanch contributed to this article.

References:
Huntington, T.G., and G.R. Aiken. 2005. Dissolved organic carbon export from the Penobscot River Basin to the Gulf of Maine. Presented at the American Geophysical Union Fall Meeting, San Francisco, CA. EOS Transactions of the American Geophysical Union 86 (52), abstract #B53A-07

Kahl, J.S., S.A. Norton, C.S. Cronan, I.J. Fernandez, T.A. Haines, and L.C. Bacon. 1991. Controls on surface water chemistry in Maine, pp 203-236 in Regional Case Studies: Acid Deposition and Aquatic Ecosystems (D. Charles, ed.). New York: Springer-Verlag.

Jackson, J.K., A.D. Huryn, D.L. Strayer, D.L. Courtemanch, and B.W. Sweeney. 2005. Atlantic Coast Rivers of the Northeastern United States, pp. 21-63 in Rivers of North America (A.C. Benke and C.E. Cushing, eds.). Boston: Elsevier/Academic Press.

Johnson, K., and J.S. Kahl. 2005. A Systematic Survey of Water Chemistry for Downeast Area Rivers (ASCpH Survey) Final Report to the Maine Atlantic Salmon Commission. Senator George J. Mitchell Center for Environmental and Watershed Research, Orono, ME.

Mitnik, P. 2002. Penobscot River Data Report. Maine Department of Environmental Protection, Augusta, ME. DEPLW-0484.

Mitnik, P. 2003. Penobscot River Modeling Report Draft April 2003. Maine Department of Environmental Protection, DEPLW-0582.

WARNING

Fish caught in the Penobscot River are contaminated with mercury, dioxin, and PCBs.

Women who are pregnant, nursing, or may become pregnant, SHOULD NOT EAT any freshwater fish from Maine's inland waters. Except, for brook trout and landlocked salmon, 1 meal per month is safe.
Children under age 8 SHOULD NOT EAT any fish from Maine's inland waters. Except, for brook trout and landlocked salmon, 1 meal per month is safe.
All other adults and children older than 8 CAN EAT 1-2 fish per month.

For three hundred years, from the arrival of Europeans to the passage of the Clean Water Act in 1972, New England rivers were treated as sewers for human and industrial waste. The Penobscot was not spared this fate, and the river today is still recovering from centuries of human use.

Land clearing and sewage were the first sources of pollution in the river, but it wasn't until the lumbering boom of the mid-1800s and subsequent development of the pulp and paper industry that pollution became a noticeable problem in the river.

An estimated four percent of all logs driven on the Penobscot River sank before the drive reached its end. Since the first lumbering done on the river in 1772, this four percent amounted to roughly 400 million board feet of lumber left on the bottom of the river (Davies, 1972). Mills along the river and its tributaries dumped sawdust, edgings and bark into the water (a practice that was still going on as recently as the 1950s; Cutting 1959). The sawdust, fine and light, traveled down to the estuary, where the back-and-forth mixing of the tides forced fine particles to settle out. The sawdust formed a soft carpet of decomposing wood particles, up to two feet thick in some tidal flats (Meister, 1958).

At one location near Verona Island, sawdust made up 15% of river sediment (Haefner, 1967; Shorey, 1969). Frankfort Flats, across the mouth of Marsh River, is another depositional area with high concentrations of sawdust.

In addition to lumber industries, flour mills and shipbuilding predominated in 1840, and by 1860 the cotton and tanning industries had become established. The rise to eminence of the paper industry had to await the discovery of the practicability of the use of pulp wood, "a raw material with which Maine was so liberally endowed" (Goode, 1934).

With the discovery that paper could made from wood pulp, and the tree harvest shifting to smaller softwoods (since old growth was getting scarcer), the age of Big Paper began on the Penobscot. The first sulphite mill in Maine was that of the Eastern Manufacturing Company at South Brewer, which began operations in the latter part of 1889. Orono Pulp and Paper Company started that same year, and Howland Falls Pulp Co. followed in 1891 (Goode, 1934). The paper-making process discharged large amounts of organic matter and solids which rapidly depleted oxygen in the receiving water. By 1960, In addition to numerous pulp and paper mills, there were 22 leather plants and 25 textile plants in the lower Penobscot watershed (Maine Department of Economic Development, 1957). Residents began to voice concerns about pollution's effect on fisheries and drinking water supplies (Judd and Beach, 2003).

"Today's Penobscot, with discolored waters and carrying scum and exhaling offensive odors, repels sportsmen and other recreationists. Few fishermen will wet a line in such waters and fewer still will eat fish taken from these waters. Downstream from Bangor, the Penobscot is so severely polluted that boats cannot be kept in the river because of the way the river fouls the paint." Richard E. Griffith, Regional Director, Bureau of Sport Fisheries and Wildlife, U.S. Dept. of the Interior (U.S. FWPCA, 1967).

The 1972 Penobscot River Study, conducted by the University of Maine, concluded that the Penobscot River was periodically overloaded by oxygen-demanding wastes, and as a result could not support most fish species or be used for municipal water supply (the City of Bangor stopped using the river for drinking water in 1959). The study concluded that the river had been appropriated as a flume for waste assimilation and transport and as a channel for navigation:

"From midstream to the west channel [below Great Works] there is increasing turbidity and large clumps of sewage fungus and sludge can be seen in the water. During the months of August and early September sewage fungus covers every solid object along the west bank and gives a grayish cast to the water. Submergent vegetation is scarce at midchannel and wood chips can be observed floating over the entire surface of the river. At the southern tip of Marsh Island, the particulate matter, sewage fungus, sludge, etc., is distributed from the west bank three quarters of the way to the east bank. This is apparently due to dilution and mixing effects of the extensive rapids immediately above the southern tip of Marsh Island. The water flowing around the western part of Ayers Island appears clear. The clarity of the water probably results from the deflection of the turbid Penobscot River by the water from the Stillwater River and a large gravel bar at the head of Ayers Island. From Ayers Island to the Veazie dam the channeling effect of the particulate matter is still noticeable. On a hot, still day, large sludge mats of up to 1 m or more in diameter are common on the river's surface along this entire stretch." (Penobscot River Study, 1972).

Around this same time, biologists at the University of Maine began studying aquatic life in the river, looking at macroinvertebrate communities above and below the paper mills.
Downstream of Lincoln, the riverbed was covered with sewage bacteria and the invertebrate community was restricted to worms, leeches, and pollution-tolerant midge larvae. Low dissolved oxygen and high amounts of solids contributed to "general unaesthetic conditions" in the lower river and upper estuary below Bangor (DEP 1976).

As with most of the nation's waters, the Clean Water Act is a milestone in the pollution history of the Penobscot. After passage of the Act in 1972, the Penobscot River was listed as Water Quality Limited from Millinocket to the Weldon Dam. In response to the Clean Water Act, the cities and mills began upgrading wastewater treatment. In some places like Bucksport and Winterport where raw sewage was still being discharged to the river, treatment plants were built to at least primary standards. As a result, pollutant loads to the river decreased by 85% and all of the DEP's sampling sites improved in water quality and macroinvertebrate communities (Davies and Tsomides, 1999).

The Maine Department of Environmental Protection continues to monitor the river in partnership with the Penobscot Indian Nation, which began its monitoring program in 1992. Today, there are 47 sampling sites on the mainstem and tributaries affected by pulp and paper mill effluent, including sites on the Piscataquis and Mattawamkeag rivers. Sampling occurs every five years to coincide with the NPDES licensing schedule. The Penobscot Nation has established a network of sampling sites for basic chemistry, temperature, bacteria, and dissolved oxygen.

The amount of wastewater entering the river is small compared to its total volume: for every gallon of effluent, the river has 56 gallons of clean water to dilute it. This fact, combined with the large area of the watershed that is covered in forest and natural land cover, results in good to outstanding water quality in the watershed. Even the mainstem in the most populated sections is relatively clean, especially when compared to rivers in more developed southern parts of the state and the rest of New England. However, significant challenges remain.

In 2000, the largest sources of nutrients to the Penobscot were the Great Northern Paper mills in Millinocket and East Millinocket and the city of Bangor, the largest population center in the watershed. The levels of nitrogen and phosphorus entering the river led DEP modeler Paul Mitnik to declare that "there is little, if any, assimilative capacity left in the Penobscot River." Two years later in another report, Mitnik concluded that "eutrophication on the Penobscot, although not severe, could be approaching levels of concern that may prove to be an issue in the future."

Although much of the river was upgraded to Class B in 2003, the mainstem of the river is still Class C from the confluence of the East and West branches to the confluence of the Mattawamkeag River. Sections of the West Branch, Millinocket, Combolasse, Mattawanacook, and Kenduskeag streams are also Class C. http://janus.state.me.us/legis/statutes/38/title38sec467.html

Wastewater treatment plants, pulp and paper effluent, and stormwater runoff continue to affect water quality in the Penobscot River. The estuary and bay are affected by both upstream and local sources of pollution. Toxic contamination remains a problem in some parts of the river, the legacy of the watershed's industrial history.

Other concerns have emerged. Chemicals such as flame retardants, pharmaceuticals, caffeine, and hormones are not removed by traditional wastewater treatment, and pass unchanged into the river. The effects of these chemicals on river fish and wildlife are still unknown.

Today, the remaining pulp and paper mills and municipal wastewater treatment plants are the largest sources of pollution directly discharged to the Penobscot. Eighteen million gallons of wastewater flow out of the Bangor treatment plant every day. Winterport and Bucksport only have primary treatment plants, although their contribution to total pollutant loads is only a fraction of the larger plants (Mitnik, 2003).

As more people move to the region and industrial sources cease operation or improve waste treatment, municipal wastewater and non-point source stormwater runoff that results from development and deforestation will likely become the watershed's greatest pollution concern. If these nutrient sources are not addressed, they could shift the river towards overenrichment, since there is little capacity left in the river to assimilate — or dilute — pollution (Mitnik, 2003). Pollution from remote sources that drifts into the watershed from the atmosphere — such as persistent toxics and mercury from coal-fired power plants in the Midwest — will continue to be a concern in the Penobscot watershed.

Downstream impacts from upstream assaults: Pollution in the estuary and bay

In 1966, the Commissioner of Sea and Shore Fisheries for the State of Maine ordered the closure of the remaining shellfish beds in Searsport and Stockton Springs because of pollution, eliminating shellfish harvesting in the river and bay except for small coves around Islesboro. The closure sparked investigation by the Federal Water Pollution Control Administration, motivating industries, municipalities, and fisheries managers to finally address pollution in the Penobscot (U.S. FWPCA, 1967).

Most of the pollution in the bay came from upstream sources. Sulphite liquors discharged by pulp and paper mills could be found throughout upper Penobscot Bay, and formed stinking sludge deposits on the tidal flats. This waste depleted the oxygen in the water (in the summer of 1963, there was zero oxygen in the water between Bangor and Winterport). Bangor, Brewer, and other towns contributed the bacteria-laden raw sewage of 70,300 people to the river.

Added to the pollution in the bay that originated from upstream were local sources of waste from industrial facilities and poultry processing plants. Chicken entrails floated in Stockton Harbor. A film of animal fat and feathers coated the water around Sears Island (U.S. FWPCA, 1967). For three months in 1971, 5,000 gallons of oil leaked from an Air Force storage facility, saturating the muddy sediments and killing clams in Long Cove. Clams came out of their burrows and died on the flats. Clams that didn't die right away developed tumors. By August, 85% of the estimated 50 million marketable clams were dead. The Searsport-Stockton Springs area was one of the most productive clam habitats in the Gulf of Maine, but was closed to harvesting in 1966 as a result of pollution. The oil spill was another blow to an already burdened ecosystem.

Sampling of Penobscot Bay sediments in 1985 found PAHs, metals, and PCBs throughout the bay. Concentrations were highest at the entrance to Belfast Harbor, at Searsport, and at the mouth of the river. PAHs come from incomplete combustion of petroleum products, and drift through the air as tiny particles, falling onto the water and slowly settling to the bottom. The levels in Penobscot Bay were similar to pollution in much more populated and developed areas like New York and Massachusetts (Johnson et al., 1985). Metal concentrations also were higher at the mouth of the river, suggesting upstream sources of contamination. The levels of chromium, copper, and lead were comparable to other industrialized areas in New England. Nickel and zinc levels were even higher.

Legacies of Toxic Contamination 

Pine Tree Tannery
Pine Tree Tanning, located at the confluence of the Piscataquis and Penobscot, operated from 1957 to 1973.

Bangor Gas Works
Ten acres of the river bottom along the Bangor Waterfront are covered with coal tar, the legacy of the former Bangor Gas Works (now the site of Shaw's Supermarket and Second Street Park). From 1852 to the 1960s, Bangor Gas Works extracted gas from coal, supplying the gas to the city for electricity and storing the thick tar that remained in large tanks. The facility closed in 1963. The tar deposit begins at an old sewer pipe and extends 1,400 feet downstream. The City believes the old Gas Works is the source of the coal tar. The company that now owns the property claims they are only partly responsible, since there were many other potential sources along the waterfront, including two tar distribution facilities at Dunnett's Cove, one of which was operated by the city. In the 1950s and 60s, local residents reported fumes backing up through the sewers and tar sheens on the river. The gas works plant was demolished in 1978. The case is currently in court, but a $12 million proposed cleanup plan would cap and stabilize the sediment to prevent migration of contaminants. The tar deposit is eroding very slowly, but on hot summer days blobs of tar may bubble to the surface, and an oily sheen may be visible. For more information, contact Kathy Howatt, project manager for the site at DEP, 287-4861.

Bangor International Airport/Maine Air National Guard
Bangor International Airport and Maine Air National Guard are located on the former site of Dow Air Force Base. Military and airport use of the property resulted in contamination from fuel spills, hazardous waste dumping, and fire training activities. Most of these areas of contamination have been cleaned up through DEP and EPA activities. The majority of the airport property, as well as the heavily commercialized Union Street/Griffin Road area, drain to Birch Stream, a tributary of the Kenduskeag Stream. Birch Stream does not meet minimum water quality standards and the DEP is currently drafting a TMDL/watershed management plan. Today, accidental spills of jet fuel and deicing chemicals continue to threaten Birch Stream, which drains to the Kenduskeag just over one mile upstream from its confluence with the Penobscot.

HoltraChem
From 1967 to 2000, the HoltraChem facility in Orrington, Maine used mercury to make chlorine and other chemicals for the paper industry. 82 tons of mercury were stored on the site at any one time. The plant legally and illegally discharged mercury in a series of spills to the air, water, soil and the Penobscot River. The state knew the plant was discharging mercury to the Penobscot River, to unlined brine sludge pits, and to the air in 1970, but the site was not investigated until the 1990s. In April 2000, the Maine Peoples Alliance (MPA) and the Natural Resources Defense Council (NRDC) filed a lawsuit to force the site's owner to address the downstream mercury contamination. The levels of mercury found in fish from the Penobscot River near the plant are dangerous to humans; a pregnant woman could not eat a single Penobscot fish from near Holtrachem without endangering fetal health. Concentrations of mercury found in Penobscot River sediments from Frankfort Flats and Fort Point Cove were above 0.15 parts per million (ppm), the level that can have an adverse affect on bottom-dwelling organisms. Concentrations as high as 4.6 ppm have been found in Frankfort Flats (Livingston, 2000). Lobsters caught near Verona Island and Fort Point Cove in the mid-1990s had the highest levels of tomalley mercury in Maine. The court ruled in favor of MPA and NRDC, stating, "the Court concludes that the methylmercury downriver of the plant, resulting, in part, from Mallinckrodt's actions at the plant site, may present an imminent and substantial endangerment to public health and the environment…The evidence clearly demonstrated that the Penobscot River is contaminated with mercury through the mouth of the river and into the bay." The court ordered that Mallinkrodt, operator of the plant from 1967 to 1982, pay for a study of mercury contamination downriver of the plant site (U.S. District Court of Maine, 2002; see also Schmitt, 2004).

References:

Cutting, R.E. 1959. Penobscot River Salmon Restoration. Maine Atlantic Sea-Run Salmon Commission, Augusta, ME.

Davies, R.S. 1972. History of the Penobscot River: Its use and abuse. M.S. Thesis, University of Maine.

Davies, S.P., and J.L. Tsomides. 1999. Biomonitoring Retrospective: Fifteen Year Summary for Maine Rivers and Streams. Maine Department of Environmental Protection, Augusta, ME. PDF
Biomonitoring Retrospective - Introduction, Summary, Map, Table.

Goode, R.D. 1934. The economic growth of the pulp and paper industry in Maine. M.S. Thesis, University of Maine.

Haefner, P.A. 1967. Hydrography of the Penobscot River (Maine) Estuary. J. Fish. Res. Bd. Canada 24:1553-1571. PDF

Johnson, A.C., P.F. Larsen, D.F. Gadbois, and A.W. Humason. 1985. The distribution of polycyclic aromatic hydrocarbons in the surficial sediments of Penobscot Bay (Maine , USA) in relation to possible sources and to other sites worldwide. Marine Environmental Research 15:1-16.

Judd, R.W., and C.S. Beach. 2003. Natural States. Resources for the Future.

Livingston, R.J. 2000. Mercury Distribution in Sediments and Mussels in the Penobscot River Estuary, March 2000.

Maine Department of Economic Development. 1957. Development resources of the Penobscot region. Augusta, ME.

Maine Department of Environmental Protection. 1976. Penobscot River Basin water quality management plan. Augusta, ME.

Meister, A.L. 1958. The Atlantic salmon, Salmo salar Linnaeus, of Cove Brook, Winterport, Maine. M.S. Thesis, University of Maine.

Mitnik, Paul. 2003. Penobscot River Draft Modeling Report April 2003. DEPLW-0582, Maine Department of Environmental Protection, Augusta , ME. http://www.state.me.us/dep/blwq/comment.htm#mod PDF

Penobscot River Study Team. 1972. Penobscot River Study, Vol. 1. University of Maine.

Schmitt, C. 2004. Mercury, a River, and a Few People Who Cared. Northern Sky News, Issue 26.

Shorey, W.K. 1973. Macrobenthic Ecology of a Sawdust-Bearing Substrate in Penobscot River Estuary (Maine). J. Fish. Res. Bd. Canada 30:493-497. PDF

U.S. District Court of Maine. Memorandum of Decision and Order, Maine Peoples Alliance and Natural Resources Defense Council, Inc., v. Holtrachem Manufacturing Company, LLC and Mallinckrodt Inc. Civil no. 00-69-B-C United States District Court of Maine, July 29, 2002. PDF

U.S. Federal Water Pollution Control Administration. 1967. Proceedings: Belfast, Maine April 20, 1967, Conference in the Matter of Pollution of the navigable waters of the Penobscot River and Upper Penobscot Bay and their Tributaries.

Contacts:

• Dave Courtemanch, Maine DEP (general water quality)
• Susan Davies, Maine DEP (aquatic life criteria)
• Dan Kusnierz, Penobscot Nation (water quality north of Milford )
• Barry Mower, Maine DEP (toxic contaminants, fish contamination

CURRENT RESEARCH

Tracking Stormwater Quality Using Real-Time In-Situ Fluorescence
John Peckenham, University of Maine

Aluminum levels in downeast Maine watersheds. McCormick, S., USGS. Conte Anadromous Fish Laboratory. Diffuse gradient in thin film (DGT) samplers deployed in Maine rivers in 2006 to measure ambient, cumulative aluminum levels in Maine rivers. Sample locations in the Penobscot drainage include Cove Brook, Pleasant River, Piscataquis River, and the mainstem in Bradley and Eddington.
Contact: Trent Liebich

Mercury in water and sediment in the Penobscot estuary south of Orrington.
Aria Amirbahman, University of Maine.

Water quality monitoring at over 100 sites in the Penobscot River and its tributaries (north of Indian Island).
Dan Kusnierz, Penobscot Indian Nation, 207-817-7361.

Dioxin monitoring program and Surface Water Ambient Toxics (SWAT) monitoring program.
Barry Mower, Maine DEP (with Penobscot Nation). These programs include approximately 12 sites on the Penobscot River. Parameters include contaminants in fish tissue, semi-permeable membrane devices, and caged freshwater mussels, 1990-present. Annual reports are available.

Water quality modeling
DEP is reconstructing their water quality model for the river for the purpose of allocating waste loads and discharge licenses. The model had to be revised because of changes in industry along the river and to support development of a TMDL. The TMDL is required by EPA because some sections of the river do not meet water classification standards. Sampling took place in July 2007 for DO, TSS, BOD, conductivity, bacteria, TP, and chlorophyll-a. The EPA assisted with sampling for sediment oxygen demand in August. The draft model and report are expected in December 2007.
Contact Don Albert,Maine DEP, 207-287-7767.

Water quality monitoring at Eddington
The U.S. Geological Survey has installed equipment to continuously measure water column velocity, suspended sediment, pH, temperature, specific conductance, and dissolved oxygen at the Eddington stream gage.

Organic carbon export from the Penobscot watershed

Collin Roesler of the University of Maine School of Marine Sciences is leading a team of scientists who are studying optical properties of Penobscot river water in relation to land coverage and terrestrial inputs of organic carbon. Chlorophyll, solar radiation, ocean color, and particle scattering are measured at GoMOOS buoy F. Sensors in the lower river and estuary monitor dissolved and particulate organic carbon, particulate C:N, and fluorophores entering the bay. These data are supplemented with grab samples from throughout the watershed. The project is funded by NASA and will continue through 2009.

Hazardous waste sites and spills are listed by town and are contained in a DEP database/GIS of potential threats to groundwater. DEP is working to make this information available and searchable online.