Great Flats Aquifier

The Great Flats, or the Schenectady Aquifer, is a unique groundwater resource and is one of the most productive aquifers in New York State.  The Great Flats Aquifer serves as a reliable source of high quality drinking water for nearly 150,000 residents of both Schenectady and Saratoga Counties.  On an average day, approximately 25 million gallons of water are withdrawn from the aquifer by the five Schenectady County municipalities listed below: 

City of Schenectady
Village of Scotia
Town of Glenville
Town of Niskayuna
Town of Rotterdam

Aquifer Location

The Great Flats Aquifer is located in the Mohawk River Valley in Schenectady County, New York.  In total, the aquifer comprises approximately 25 square miles in Schenectady County.  The municipal boundaries for the City of Schenectady, Village of Scotia, and the Towns of Glenville, Niskayuna, and Rotterdam all rest atop the aquifer system making this a true intermunicipal resource.   The map below shows the location of the Great Flats Aquifer.  The four colored zones correspond to a series of aquifer protection zones.  Zone 1, or the green shaded area, represent that aquifer’s watershed.  Zone 3, or the darker blue, corresponds to the approximate boundaries of the actual Great Flats Aquifer system. 

Geologic Origin of the Great Flats Aquifer

The Great Flats Aquifer, is a large deposit of saturated (filled with water) coarse sand and gravel that provides drinking water to the residents of Schenectady County.  The sand and gravel was deposited approximately 10,000 years ago as continental glaciers were retreating northward out of New York State.  Specifically, a large glacial lake referred to as Glacial Lake Iroquois and the precursor to the current-day Lake Ontario drained down the Mohawk Valley from west to east.  Some researchers estimate that the flow in the Mohawk Valley was over 100 times greater than the current flow of the Mohawk River.  This incredible flow of water provided the energy required to transport and ultimately deposit the large cobbles, coarse gravel, and sand that make up the aquifer system. 


In 1897, the City of Schenectady developed the first municipal well field utilizing the Great Flats Aquifer (shown in image to the right).  The well field consisted of three large diameter circular dug wells.  The wells were an impressive 47 feet in diameter and 50 feet deep.  This first well field was located along the current Rice Road near NYS Canal Lock 8.

Today, the City of Schenectady, Village of Scotia, and Towns of Glenville, Niskayuna, and Rotterdam operate six well fields and are permitted by the New York State Department of Health (NYSDOH) to withdraw approximately 65 million gallons of water daily from the aquifer.  The City has the largest permitted capacity of 35 million gallons of water daily.  It is rare that the municipalities approach their capacity.  Instead, on an average day, the combined groundwater withdrawal is approximately 25 million gallons.  

Occasionally the municipalities will impose lawn-watering restrictions.  Typically, these restrictions are commonly activated because of transmission limitations of the large quantities of water and not because the aquifer cannot meet the demands during dry periods.    

Aquifer Protection Program – The Schenectady County Intermunicipal Watershed Rules and Regulations Board

The Schenectady County Intermunicipal Watershed Rules and Regulations Board (Watershed Board) formed on the 11th day of July, 1991.  The Watershed Board is an intermunicipal agency consisting of the five communities that rely on the aquifer system as a drinking water supply. Together, the five communities and Schenectady County work together to protect the Great Flats Aquifer; one of the County’s most important natural resources. 

The chief elected officials for each municipality represent the Watershed Board members.  Each Watershed Board member appoints a Technical Committee member.  The Technical Committee provides technical support to the Watershed Board.  These Technical Committee members represent engineering, planning, and public works department staff members. Schenectady County provides additional technical support through the Groundwater Management Planner position.  The table below lists both the current Watershed Board members and the Technical Committee members.

The four aquifer protection zones include:

Aquifer Protection Zone 1 – This Zone is also referred to as the Wellhead Protection Area.  Zone 1 immediately surrounds a wellfield and is the most restrictive in terms of land use.  Essentially in the aquifer protection zone, land use is restricted to activities related to the production of drinking water.  This is the light-blue shaded area on the map above.

Aquifer Protection Zone 2 – This Zone is also referred to as the Primary Recharge Area and immediately surrounds and includes Zone 1. This is the light-orange shaded area on the map above.

Aquifer Protection Zone 3 – This Zone is also referred to as the General Aquifer  Recharge Area and is the land outside of the Primary Recharge Area (Zone 2).  Aquifer Protection Zone 3 generally corresponds to the boundaries of the Great Flats Aquifer.  Within this zone, runoff and precipitation flow directly and rapidly into the ground; thereby recharging the aquifer, but not necessarily a specific wellfield.  This is the darker-blue shaded area on the map above.

Aquifer Protection Zone 4 – This Zone is also referred to as the Tributary Watershed and is the land outside of the aquifer area that contributes runoff overland and/or through surface streams for groundwater recharge. This is the green shaded area on the map above.

Role of the Watershed Board

The Watershed Board is responsible for implementing the aquifer protection program in Schenectady County.  In cooperation with the Schenectady County Ground Water Management Planner and the Schenectady County Department of Health, the Watershed Board:

  • Educates and advises the local governments, residents, and citizen groups about the Great Flats Aquifer and the need for aquifer protection;
  • Review development proposals of regional impact within the aquifer boundaries relative to the Watershed Rules and Regulations and issue comments to approval authorities;
  • Apply for grants that support the aquifer protection program;
  • Implement a long-term water level monitoring program to evaluate aquifer performance;
  • Pursue legal action against property owners that are in violation of the Watershed Rules and Regulations;
  • The Watershed Board meets periodically, but at a minimum one to two times per year to elect a chairman, approve the operating budget, and discuss issues related to the aquifer system.  A quorum of the Board consists of at least three members of the Board for the transaction of business.  

The Technical Committee typically meets more frequently to discuss, in more detail, individual projects or issues related to the aquifer.  The Technical Committee commonly invites applicants to meetings to present development proposals.  The Ground Water Management Planner serves as the chairperson for the Technical Committee, prepares the meeting agenda, and meeting minutes. 

Funding for Watershed Board activities is based on the total amount of water withdrawn from the aquifer on an annual basis.  Although the Watershed Board does not rely on grants, the awarding of grants serve as a secondary funding source to support aquifer-related activities.

Why Was the Watershed Board Created

The Schenectady County communities recognized the importance of protecting the Great Flats Aquifer system.  The size, importance, susceptibility, and intermunicipal use of the Aquifer system necessitated the formation of an intermunicipal agency to protect the resource.  The following timeline shows some of the major milestones in the formation of the Watershed Board:

  • August 29, 1982 Mayor Frank Duci (City of Schenectady) petitioned the EPA to designate the Great Flats Aquifer, or Schenectady Aquifer, as a Sole Source Aquifer; 
  • February 1985 United States Environmental Protection Agency designates the Great Flats Aquifer as a Sole Source Aquifer;
  • 1985 Schenectady County forms an Aquifer Protection Committee and prepares an aquifer protection strategy;
  • February 1989 Critical Aquifer Areas mapped in a report prepared by a local consulting firm;
  • July 11, 1991 an Intermunicipal Agreement in signed by the five communities creating the Watershed Board;
  • 1992 the Watershed Board hires a Ground Water Management Planner as a Schenectady County staff person

A Sampling of Work Activities and Accomplishments

The Watershed Board has been a strong advocate for legislation to increase penalties for violations of the public health law aimed at protecting drinking water supplies.  Early in 2008, the legislation was passed by the Senate and must now be acted on by the Assembly.

  • Watershed Board staff are currently implementing an EPA Wetland Assessment Grant.  The grant focuses on better understanding the relationship between the aquifer system and the overlying wetlands.
  • Identifying funding sources/options in order to support the purchase of critical properties that represent a threat to the drinking water resources.
  • Meeting with the major rail lines that pass through Schenectady County and above the aquifer system to discuss emergency response procedures and to make the rail lines aware of the sensitive aquifer areas.
  • Routinely reviewing development applications of regional impact within the aquifer system.
  • Currently reviewing the Watershed Rules and Regulations to determine if an update is warranted.





Dept. of Economic Dev. & Planning
Schaffer Heights, Suite 303
107 Nott Terrace
Schenectady NY 12308
(518) 386-2225 (p)
(518) 382-5539 (f)

Ray Gillen

Jason Pelton
Schenectady County Groundwater
Management Planner