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Total Maximum Daily Loads (TMDLs)

A Total Maximum Daily Load (TMDL) may be viewed as a pollutant budget for an impaired waterbody. It is the maximum amount of a pollutant that a waterbody can receive and still meet surface water quality standards

Waters of the State are regularly assessed to determine if surface water quality standards are met and designated uses are supported. Waters that do not meet the applicable standard(s) or support the applicable designated use(s) are placed on the 303(d) List of Water Quality Limited Waters. Section 303(d) of the federal Clean Water Act requires development of a TMDL for the pollutant(s) responsible for each impairment. The TMDL must be calculated so that standards will be attained in consideration of critical conditions and seasonal variation and must include a margin of safety (MOS) to account for uncertainty.  The TMDL is allocated among all of the sources of the pollutant, including point sources, nonpoint sources, and natural background. Point sources are those regulated under the federal Clean Water Act, such as wastewater treatment facilities, combined sewer overflows and stormwater, and receive wasteload allocations (WLAs). Nonpoint sources are diffuse sources, not regulated under the Clean Water Act, such as overland runoff and air deposition, and receive Load Allocations (LAs).  The MOS can be an explicit part of the TMDL equation or can be accounted for through conservative assumptions in calculating the TMDL.

A TMDL implementation plan is developed to identify the suite of measures that are needed to reduce loads from each source to levels that will meet surface water quality standards.  The measures include both regulatory and non-regulatory actions.  Regulatory measures typically include effluent limitations or additional measures that are incorporated into wastewater or stormwater permits issued pursuant to the New Jersey Pollutant Discharge Elimination System (NJPDES).  Non-regulatory measures include best practices for agricultural land use, riparian restoration, and promoting watershed stewardship activities such as rain gardens and rain barrels.      

Federal regulations concerning TMDLs are contained in USEPA's Water Quality Planning and Management Regulations (40 CFR 130,7(c)), and New Jersey’s rules are set forth in the Water Quality Management Planning rules at N.J.A.C. 7:15-6.

The identified water quality impairments are ranked and prioritized for TMDL development as part of the development of the 303(d) List of Water Quality Limited Waters.  The factors considered in ranking TMDLs are contained in the Integrated Water Quality Monitoring and Assessment Methods (Methods Document).   

Many of the listed impairments are caused primarily by nonpoint sources and regulated stormwater sources.  For these impairments, development of a watershed restoration plan can be an effective alternative to a formal TMDL to characterize pollutant sources, the reductions needed to attain standards, and the means to achieve the reductions.  When adopted as an amendment under the Water Quality Management Planning rules, a watershed restoration plan can be implemented using measures such as those that would appear in a TMDL implementation plan (refer to N.J.A.C. 7:15-5.25(g)). BEAR is pursuing this approach for impairments where stormwater and nonpoint sources are believed to be dominant.

Status of New Jersey TMDLs:

The status of all TMDLs that have been developed by the Department can be obtained from the link below.

New Jersey TMDLs

The link opens an Excel spreadsheet, which may be sorted or filtered as needed using the tools provided by the software application. Please note the following explanation of terms used in this spreadsheet: A TMDL is "proposed" when the Department publishes the TMDL Report as a proposed Water Quality Management Plan (WQMP) amendment in the New Jersey Register (NJR) for public review and comment. Following the public comment period, the Department prepares a response to comments and any required revisions to the TMDL. The revised document with response to comments is “established” upon submittal to EPA for review. Following EPA’s review and approval process, the TMDL is deemed “approved” and can then be “adopted” as an amendment to the WQMP. The notice of adoption is published in the NJR. The Department is in the process of adopting each of the TMDLs shown as "approved."

Additional Information About TMDLs:

New Jersey Integrated Water Quality Monitoring and Assessment (NJDEP Web site)
USEPA TMDL Tracking Web Site (ATTAINS)
Stormwater in New Jersey (NJDEP Web site)
Mercury Research (NJDEP Office of Science Web Page)

For more information, please contact Barbara Hirst, Chief, Bureau of Environmental Analysis and Restoration, at (609) 633-1441.

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