Department of Environmental Conservation

D E C banner

Aquatic Habitat Protection

The Hudson River near the Hudson River Highlands
Several power plants withdraw large quantities
of cooling water from the Hudson River

There are several programs within the Division of Fish, Wildlife and Marine Resources that focus on the protection of aquatic habitat including the Protection of Waters program, the Instream Habitat Protection program, and the work of the Bureau of Ecosystem Health's Steam-Electric Unit to minimize the adverse aquatic impact from cooling water use by power plants and other industrial and commercial facilities. Staff in these programs evaluate the impact of existing and proposed construction, development or water use on streams, rivers and other waterbodies.

Final Policy on Determination of Best Technology Available (PDF 70 KB)

This policy, established in July 2011, describes the reductions in impingement mortality and entrainment required to minimize the adverse environmental impact caused by industrial facilities operating a cooling water intake structure (CWIS) in connection with a point source thermal discharge. The operation of CWIS causes injury and mortality to fish and other aquatic organisms through impingement at the intake and/or entrainment through the cooling system. Through this policy, the Department identifies closed-cycle cooling or its equivalent as the performance goal for best technology available (BTA) pursuant to Section 704.5 of 6NYCRR, and Section 316(b) of the federal Clean Water Act in State Pollutant Discharge Elimination System (SPDES) permits issued by the Department in accordance with ECL Article 17, Title 8, and Part 750 of 6NYCRR.

The Department made a Determination of Non-Significance (PDF) (71 KB) which means that the policy does not have a significant adverse impact on the environment and a draft impact statement was not required. Furthermore, the many public comments on the draft policy were summarized and addressed in a Response to Public Comments (PDF) (94 KB) document.

Cooling Water Impact Mitigation

The Dunkirk Generating Station is located on Lake Erie
The Dunkirk Generating Station, located on the
shores of Lake Erie

The Bureau of Ecosystem Health's Steam-Electric Unit (SEU), is made up of biologists who work to mitigate the adverse aquatic impacts resulting from the operation of industrial and commercial cooling water intakes. Steam-electric stations such as fossil fuel and nuclear generating plants use by far the greatest volume of cooling water from our lakes, rivers and marine district and as such, their impacts on aquatic ecosystems are greater. For this reason, the Department focused its limited resources on mitigating the aquatic impacts from the steam-electric industry. However, the impacts from other users of cooling water in New York such as commercial offices (air conditioning) and the cement, salt and sugar industries are now being addressed.

As a consequence of withdrawing water for cooling, fish and other aquatic life may be drawn into the facility and killed when larger individuals become impinged on the intake screens (designed to keep debris in the water from entering the plant), or when early life stages of fish such as eggs and larvae and other small aquatic life pass through the screen mesh and into the station (a process called entrainment). In 2005, the United States Geological Survey (USGS) estimated that New York ranks 3rd among the nation in using once through cooling water for steam electric power generation (USGS 2005 water use report) . Based on data collected by the Steam Electric Unit, New York steam electric plants use over 6 trillion gallons of cooling water annually, resulting in the impingement and entrainment of more than 17 billion fish of all life stages each year. A technical report (PDF) (928 KB) evaluating the relationship between cooling water use, electrical generation, and impingement and entrainment impacts has been produced by the Department and is available here. Adverse impacts to aquatic life can also occur through the discharge of cooling water (the temperature often raised by 10 to 20 degrees F) back to the lake or river, a process known as thermal pollution. Thermal pollution can kill fish outright, block fish migrations, cause the growth of nuisance species, and create other problems as well.

Fish killed due to impingement on a power plant intake screen
These fish were killed due to impingement
on a cooling water intake screen

The goal of the SEU is to minimize the mortality to fish caused by the operation of cooling water intakes. Both Section 316(b) ( of the federal Clean Water Act and New York State regulations (6NYCRR Part 704) (link leaves DEC's Website) provide the legal basis for our program. These laws and regulations protect our waters from thermal pollution, and require that cooling water intake structures make use of the best technology available (BTA) to minimize adverse environmental impacts. Staff review proposals for the construction of new power plants and periodically assess the operational impacts of existing stations located throughout the State. New power plants are required to use the most protective intake technologies. For existing stations, studies are conducted to determine the magnitude of impact and the actions necessary to minimize those adverse effects. BTA can be implemented through a number of ways, and each power plant, whether new or old, presents its own conditions and problems which require site specific assessment. BTA determinations can include many different mitigative technologies and often more than one technology is required at a single facility. Mitigation is aimed at minimizing adverse environmental impacts, but not at a social and economic cost that is wholly disproportionate to the related environmental benefit.

New Power Plants

The SEU is at the national forefront in applying state of the art technology to achieve BTA for mitigating impacts from cooling water intakes. For new power plants, these include requiring the use of evaporative, air cooled and hybrid cooling towers to reduce cooling water use by 95% or more, fine wedge wire intake screening and/or aquatic filter barriers to prevent fish impingement and minimize the entrainment of early life stages of fish.

The deregulation of the electric industry in New York State resulted in more than 60 proposals to build new power plants, primarily along the Hudson River estuary, the New York City harbor area, and in Long Island. Although only a few of these proposed plants were ever built, they all use a closed cycle cooling system and protective intake structures, or equivalent mitigation, to minimize impacts on aquatic resources. The Athens Generating Station, in Greene County near the Hudson River was the first major power plant to come on line under the NYS Public Service Commission's Article X siting law. The 1,080 MW station began operating in the later part of 2003. The station uses dry cooling towers and withdraws only 180,000 gallons of water per day. The withdrawal of this water results in very little impact on the aquatic organisms of the Hudson River.

In December 2001, EPA issued final regulations under Section 316(b)of the federal Clean Water Act, establishing location, design, construction and capacity standards for cooling water intakes at new (Phase I) facilities. All new electrical generating stations that withdraw more than 2 million gallons per day (MGD) of cooling water are regulated. In New York State, those subject facilities must comply with both 316(b) and NYCRR 704.5 requirements.

Existing Power Plants and Other Cooling Water Intakes

Older cooling water intakes in many ways present the most difficult challenge. Retrofitting new technologies on old systems that were never designed for such use can present difficulties. A careful site specific assessment of the station's impacts and the feasibility and costs of alternatives are required before a decision on BTA can be made. Technologies that have been required to mitigate impacts at existing facilities include:

  1. Modified Ristroph-type intake screens and return systems designed to reduce impingement stresses and safely return fish to the waterbody installed at the Dunkirk (Lake Erie) and Huntley (Niagara River) Generating Stations in 1998. In addition, installation of fine mesh screens to reduce entrainment of early life stages of fish at the Dunkirk Station were completed in 2013, and compliance testing began in the first quarter of 2014;
  2. An acoustic deterrent system installed at the J. A. FitzPatrick Nuclear Generating Station (Lake Ontario) to keep alewife from entering the cooling water intake;
  3. Forced generation outages to reduce cooling water use during fish spawning periods at Hudson River plants;
  4. A barrier net installed at the Bowline Station (Hudson River) to exclude adult fish from the intake structure;
  5. Operational restrictions to reduce cooling water flow during the winter period at several stations;
  6. Deployment of an aquatic filter barrier to exclude all life stages of fish from the water intake at the former Lovett Generating Station (Hudson River - station now retired and demolished);
  7. Installation of variable speed pumps and scheduling of unit outages, to minimize cooling water use and reduce fish mortality, completed at the Ravenswood Generating Station (East River). Compliance monitoring began in 2012, with biological sampling occurring from January 2013 to December 2014;
  8. Variable speed pumps and a fish deterrent system installed at the Danskammer Generating Station (Hudson River);
  9. At the Astoria Station located on the East River, installed variable speed pumps at all units (December 2009) and modified Ristroph-type intake screens/fish return system at Unit 50 (March 2012) and at Unit 30 (December 2013). Evaluation of the use of fine mesh intake screens also required;
  10. Installed modified fine mesh Ristroph-type intake screens and a low stress fish return system at the Arthur Kill Generating Station (Arthur Kill tidal strait). Compliance monitoring (impingement and entrainment sampling) began in the Spring of 2013.
  11. Installation of fine mesh (0.6 mm) modified Ristroph-type intake screens were completed at the East River Station (East River) in December 2013. Compliance testing (impingement and entrainment sampling) began in April 2014.
  12. Installation of variable speed pumps and modified Ristroph-type intake screens and low stress fish return system at Port Jefferson Station (Port Jefferson Harbor/Long Island Sound) by December 2014.

Where impacts are large, the optimal approach from our standpoint is to repower an existing facility into a state-of-the-art power plant. The facility can thus be redesigned into an efficient new station (e.g. using combined cycle technology) that will reduce fuel use, greatly increase thermal efficiency and minimize impacts to air and water. By incorporating BTA in the design phase, the projects can more easily accommodate technologies such as closed cycle cooling, and the most protective intake structures. In addition, this approach results in the re-use of an existing industrial site rather than disturbance to a greenfield site. The old 400 MW Albany Steam Generating Station, a once through cooled plant was successfully repowered into the Bethlehem Energy Center (BEC), a 750 MW highly efficient, combined cycle station. Through use of the combined cycle process and mechanical draft cooling towers, cooling water was reduced from approximately 500 MGD to less than 10 MGD. The new BEC began commercial operation in mid 2005. Almost twice as much electricity is now being produced at far lower impacts to the aquatic resource.

In September 2004, final regulations under Section 316(b) of the Clean Water Act became effective for cooling water intakes at existing power plants that withdraw a minimum of 50 MGD of cooling water. Staff incorporated elements of this regulation, commonly referred to as the Phase II rule, into the BTA decision making process, to be used in conjunction with NYCRR Part 704.5. However, in January 2007, the U.S. Circuit Court of Appeals for the Second Circuit remanded most provisions of the Phase II rule on grounds which included inconsistency with the Clean Water Act. EPA later suspended the rule, effective July 9, 2007. By this action, however, EPA did not suspend the provision which directs permitting authorities (such as DEC) to establish BTA requirements for existing facilities on a case by case basis, using best professional judgment. On April 20, 2011, EPA again proposed a rule to establish requirements to achieve BTA under section 316(b) of the CWA. Public comments on the draft rule were received until August 18, 2011. A final rule was scheduled to be issued by no later than July 27, 2012. However, under a modified settlement agreement, this date has been extended to June 27, 2013.

For more information on the unit's activities please contact Chuck Nieder at 518-402-9216.

In-Stream Habitat Protection

The Bureau of Ecosystem Health's Instream Habitat Protection Unit primarily functions to mitigate the adverse environmental impacts from the operation of hydroelectric stations. The operation of hydroelectric plants can cause serious ecological impacts. Fish can be killed directly as they pass through the turbines used to produce electricity. Water impounded by hydroelectric dams may cause downstream river sections to completely dry up, turn flowing rivers into ponds, and prevent upstream spawning migration of fish.


There are currently over 200 hydroelectric projects in New York State. Once every 30 to 50 years these projects are relicensed by the Federal Energy Regulatory Commission (FERC). Since the FERC relicensing process is governed by federal regulations, state laws are preempted except that we must issue a 401 Water Quality Certificate. This certificate contains conditions that will ensure water quality standards for the protection of aquatic resources are met by the project. The manner in which the project is operated can have a dramatic effect on the fish and wildlife resources. Many projects historically operated by using large drawdowns in the impoundment to release large flows through their turbines, and then shutting off flows to the river. The drawdowns in the impoundment and the shutting off of flow to the river cause serious impacts to aquatic resources. DEC staff participates in the federal process where we request studies needed to evaluate the impacts of the project and then recommend mitigation. A large group of hydroelectric projects (most owned by Niagara Mohawk Power Corp.) that were due to be relicensed in 1993 (the Class of '93) are nearly all completed. After many years of discussion and disagreement on how the projects should be operated, DEC, NMPC and a host of other interested parties have completed settlement agreements on all but one of these projects.

Aquatic Base Flow

The Instream Habitat Protection Unit also evaluates non-hydroelectric projects proposing stream base flow alterations that may result in adverse impacts to aquatic resources such as water withdrawals for snowmaking or reservoir releases. This work is conducted under the authority of Article 15 and the 401 Water Quality Certificate portion of the Clean Water Act.

For further information on the activities of the Instream Habitat Protection Unit, contact Mark Woythal at 518-402-8847.

More about Aquatic Habitat Protection: