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Allegheny River Watershed

A brief overview of this watershed and its water quality is presented below. For more detailed information about the Allegheny 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 Allegheny Watershed
Click image to view detailed map of watershed

The Allegheny River originates in north central Pennsylvania and flows west across southwestern New York State. The Allegheny River Watershed is part of the headwaters of the larger Ohio River Basin (204,000 square miles). Some of the larger tributaries of this watershed join the Allegheny River outside New York State and eventually empty into the Gulf of Mexico.

Location: Southwestern New York State

  • Most of Cattaraugus and Chautauqua Counties, and
  • Portion of southwest Allegany County.

Size: 1,920 square miles of land area within New York State.

Rivers and Streams: 4,086 miles of freshwater rivers and streams. Major tributary watersheds to the Allegheny River in New York State include:

  • Conewango Creek (1,406 river/stream miles)
  • Cassadaga Creek (586 miles, within Conewango Watershed)
  • Olean Creek (487 miles)
  • Great Valley Creek (357 miles)
  • French Creek (186 miles)

Lakes, Ponds and Reservoirs: 23 significant freshwater lakes, ponds, and reservoirs (26,335 acres), including

  • Allegheny Reservoir (10,987 acres)
  • Chautauqua Lake (13,427 acres)

How is the Water?

Water Quality in The Allegheny River Watershed

In the Allegheny Watershed, about 53% of river/stream miles, and 55% of lake, pond and reservoir acres have been assessed (see Assessment Report).

Water quality Pie Chart. Rivers: 31% good, 22% Satisfactory, 1% Poor, 47% unassessed. Lakes: 0% good, 3% satisfactory, 53% poor, 45% unassessed
Good water quality: Fully supports designated activities and uses
Satisfactory: Fully supports designated activities, but with minor impacts
Poor (Impaired): Does not support designated activities and uses
Unassessed: Insufficient data available

Water quality in much of the Allegheny River Watershed (outside Chautauqua Lake) can be characterized as satisfactory or good. Virtually all the poor water quality in the basin is the result of nutrient loads and invasive species in Chautauqua Lake, which represents half the lake acres in the watershed. Agricultural and other nonpoint sources contribute nutrients and sediment to the waters. Urban and industrial sources have also been identified in the Jamestown-Falconer area.

Major water quality concerns in the watershed are:

  • Agricultural and Other Nonpoint Sources of nutrients and various other pollutants
  • Invasive Aquatic Species which discourage recreation uses
  • Urban Stormwater and Industrial Runoff in urban areas
  • Protection of Municipal Water Supply in the Olean Creek watershed.

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.

DEC staff taking a kick sample in a stream
Biological Kick Sampling

Published Water Quality Monitoring and Assessment Reports

Watershed Management Plan

More about Allegheny River Watershed: