Top 10 Water Quality Issues in NYS
The NYSDEC Water Quality Assessment Program has identified the top ten most prevalent causes/sources of water quality impact/impairment in the assessed waters of New York State, as listed below:
- Urban Stormwater Runoff
- Aging/Inadequate Wastewater Treatment Infrastructure
- Nutrient Eutrophication
- Atmospheric Deposition and Acid Rain
- Legacy Pollutants in Sediments and Fish
- Atmospheric Deposition of Mercury
- Habitat/Hydrologic Modification
- Nuisance Aquatic Weed Growth and Invasive Species
- Pathogen Contamination of Shellfish
- Inadequate Onsite Wastewater Treatment
The graph below shows the frequency for which a specific cause/source is noted as a significant contributing factor in New York State waters. It illustrates the occurrence of each cause/source as a percentage of all waters assessed as impaired (red) or impacted (yellow).

Frequency of the top 10 water quality issues in New York
This information is drawn from the NYS Waterbody Inventory and Priority Waterbodies List. The WI/PWL is compiled by the NYSDEC Division of Water using monitoring data and information from a number of programs and sources, both within and outside NYSDEC. It contains water quality assessments for just over half of the nearly 5,000 waters identified in the statewide Waterbody Inventory. While not all waters of the state have been fully assessed, the percentages shown by the graph are considered to be representative of the causes/sources of water quality impairment throughout the state.
Each of these causes/sources is discussed in greater detail on the linked web pages and downloadable fact sheets (see below for links). These fact sheets outline the nature of the specific problem, the significance of the problem, which New York State waters are most susceptible to the problem and what is being done to address the problem.
Other Observations and Comments on Causes/Sources
- Impairments and impacts due to Atmospheric Deposition/Acid Rain may be underestimated due to the large number of smaller (under 6.4 acre) ponds in the Adirondack and Catskill regions that have not been individually assessed but are vulnerable to acid rain.
- Minor impacts and threats (yellow bar) due to Legacy Pollutants in Sediment/Fish and to Atmospheric Deposition of Mercury are considered to be underestimated as a result of a precautionary statewide fish consumption advisory for these substances that is not easily reflected in this assessment.
- Inadequate Onsite Wastewater Treatment includes impairments and impacts due to the failure of installed systems, as well as the absence of systems that result in the direct discharge of wastewater from residences in communities where a municipal wastewater system is not available.
More about Top 10 Water Quality Issues in NYS:
- Urban Stormwater Runoff - Urban stormwater runoff is a major contributing factor to the contamination of New York's waters. A downloadable fact sheet is available.
- Aging Wastewater Treatment Infrastructure - Aging wastewater treatment infrastructure is a major source of pollution of NYS water. A downloadable fact sheet is available.
- Nutrient Loadings and Eutrophication - Stormwater runoff, wastewater treatment plant discharges and agricultural activities are just some of the sources of nutrient loading in NYS waters. A downloadable fact sheet is available.
- Atmospheric Deposition and Acid Rain - Information on acid rain's effect on the waters of New York State. A downloadable fact sheet is available.
- Legacy Pollutants and Fish Consumption - Information on fish contamination from polluted sediment. A downloadable fact sheet is available.
- Atmospheric Deposition of Mercury - Most mercury in NYS waters comes from the air. A downloadable fact sheet is available.
- Habitat and/or Hydrologic Modification - Changes to streams (erosion, depth change, barriers, etc...) can cause many problems. A downloadable fact sheet is available.
- Aquatic Weeds and Invasive Species - Aquatic weeds and invasive species are a top cause of impaired water in NY. A downloadable fact sheet is available.
- Pathogen Contamination of Shellfish - Pathogen contamination of shellfish causes temporary, emergency closures of shellfish beds. A downloadable fact sheet is available
- Inadequate Onsite Wastewater Treatment - Water quality can be degraded by onsite treatment systems that do not work properly. A downloadable fact sheet is available.





