Water Quality


The harvest of shellfish within the Town of Southold is regulated by NYSDEC and the Town of Southold Trustees. The NYSDEC conducts regular sampling of shellfish growing areas for fecal coliforms and other water quality indicators in strict accordance with the National Shellfish Sanitation Program. Shellfish growing areas may be classified as certified, seasonally certified or uncertified based on water quality indicators or for administrative reasons. Administrative certifications may be based on potential or suspected pollution sources and are not necessarily indicative of poor water quality.

The 303(d) List and Total Maximum Daily Loads

Waters that are not suitable for supporting their best classified uses due to poor water quality are typically added to the NYS Section 303(d) list of impaired waters. Once added to the Section 303(d) list, the NYSDEC may develop a Total Maximum Daily Load (TMDL) based on a study of pollutant input to an impaired body of water. TMDLs may be used as the basis for regulation of municipal, industrial, commercial and/or private pollutant discharges to the impaired water. Both the initial listing of an impaired water on the 303(d) list and the subsequent development of a TMDL are subject to EPA review and approval.

Classification of Water Quality in the Town of Southold

The Draft 2020-2022 Clean Water Act (CWA) Section 303(d) List of Impaired/Total Maximum Daily Load (TMDL) Waters has been released by the NYSDEC.  The Town submitted comments on this list to NYSDEC on February 2, 2022.

The Town continuously reviews all information relevant to waterbodies currently subject to shellfishing restrictions, including the most current sanitary surveys and the information contained in the NYSDEC Priority Waterbodies List. If, after reviewing this information, it is determined that water quality in a particular body of water has improved sufficiently to remove water quality related shellfishing restrictions, the Town will request that the water body be removed from the 303(d) list. If additional water quality testing is needed to support an upgrade in the classification of a shellfish growing area, certified testers from the Town of Southold Trustees and the Shellfish Advisory Committee will work with the NYSDEC to acquire the necessary samples and deliver them to the NYSDEC lab for analysis.

The following map shows water bodies within the Town that are subject to shellfishing restrictions or water quality related regulatory requirements. Please note that this map can not be used to determine the certification status of shellfishing waters. Commercial and residential shellfish harvesters should consult the NYSDEC website prior to harvesting shellfish from Town or State waters.

Town of Southold Water Bodies with Shellfishing Restrictions or Water Quality Impairments