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St. Lawrence River Watershed

A brief overview of this watershed and its water quality is presented below. For more detailed information about the St. Lawrence River Watershed, published NYSDEC reports are also available. General information about watersheds is available at the "We All Live in a Watershed" webpage.

Facts about this Watershed

Map of NYS identifying the Saint Lawrence River Watershed
Click to view a detailed map of this watershed

The Saint Lawrence Watershed lies at the border of New York State and Canada. The Saint Lawrence River serves as the gateway between the North Atlantic and the Great Lakes. At its most downstream point in the Unites States the Saint Lawrence drains an area of nearly 300,000 square miles. Within New York State the watershed drains the northern and western Adirondack Mountains and the lake plain region of the Saint Lawrence Valley.

Location: Northern New York State

  • All of Saint Lawrence County,
  • Most of Franklin County,
  • Much of northern Jefferson, Lewis, Herkimer and Hamilton counties, and
  • Small parts of western Essex and Clinton Counties.

Size: 5,600 square miles of land area in New York State.

Rivers and Streams: 11,371 miles of freshwater rivers and streams. Major tributary watersheds to the 185 miles of Saint Lawrence River shoreline include:

  • Oswegatchie River (3,590 river/stream miles)
  • Raquette River (2,016 miles)
  • Saint Regis River (1,734 miles)
  • Grass River (1,607 miles)
  • Indian River (1,222 miles, included within the Oswegatchie watershed)

Lakes, Ponds and Reservoirs: 376 significant freshwater lakes, ponds, and reservoirs (85,723 acres), including:

  • Black Lake (7,754 lake/reservoir acres)
  • Cranberry Lake (6,795 acres)
  • Raquette Lake (5,194 acres)
  • Tupper Lake (4,858 acres)
  • Long Lake (4,094 acres)

Great Lakes Shoreline: 185 miles of Great Lakes (Saint Lawrence River) shoreline.

How is the Water?

Water Quality in The Saint Lawrence River Watershed

In the Saint Lawrence Watershed, about 40% of river/stream miles, 68% of lake, pond and reservoir acres, and 100% of Great Lakes (Saint Lawrence River) shoreline have been assessed (see Assessment Report).

Water quality Pie Chart. Rivers: 25% good, 11% Satisfactory, 5% Poor, 60% unassessed. Lakes: 14% good, 4% satisfactory, 50% poor, 32% unassessed. Shores:100% poor
Good water quality: Fully Supports designated activities and uses
Satisfactory: Fully supports designated activities and uses,
but with minor impacts
Poor (Impaired): Does not support designated uses and activities
Unassessed: Insufficient data available

Water quality in the Saint Lawrence Watershed is dominated by atmospheric deposition of pollutants that originate largely outside the basin. Acid rain and mercury deposition are the most widespread issues in the watershed. Impacts from agricultural activities are also frequently cited in this vary rural and agriculturally intensive area. Hazardous wastes and other industrial impacts associated with resource extraction are also a concern in specific areas.

Major water quality concerns in the watershed are:

  • Acid Rain which limits the fish community and aquatic life
  • Atmospheric Deposition of Mercury which restricts fish consumption
  • Agricultural Activities and Associated Runoff which contributes nutrients and sediments to waters
  • Hazardous Wastes and Legacy Industrial Impacts in the Massena Area of Concern

About Water Quality in New York State

Water chemistry sampling in a NYS stream
Water Chemistry Sampling

Each waterbody in NYS has been assigned a classification, which reflects the designated "best uses" of the waterbody. These best uses typically include the ability to support fish and aquatic wildlife, recreational uses (fishing, boating) and, for some waters, public bathing, drinking water use or shellfishing. Water quality is considered to be good if the waters support their best uses. NYSDEC routinely monitors and assesses water quality throughout the state and publishes detailed reports of these findings. For more information on these monitoring and assessment programs, see Water Quality Monitoring, Assessment and Planning.

What You Can Do!

Each of us lives in a watershed. On our Watershed Stewardship page are some tips on actions that you and your friends can take to help your watershed.

Water Information for Public Officials and Municipal Employees

On this page you will find information on: announcements, meetings, hearings, training schedules, applications, regulations, permits, guidance, and more.

Biological kick sampling in a NYS stream
Biological Kick Sampling

Published Water Quality Monitoring and Assessment Reports


More about St. Lawrence River Watershed: