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Onondaga Lake Phosphorus TMDL

On June 29, 2012 the United States Environmental Protection Agency approved the updated phosphorus Total Maximum Daily Load (PDF 2.6 MB) for Onondaga Lake. The approved TMDL reflects public comments on the draft TMDL proposed on March 28, 2012.

DEC updated the phosphorus TMDL for Onondaga Lake as allowed by the 1998 Amended Consent Judgment (see the Onondaga Lake Background Information section below for more information). Incorporating data gathered since 1998 -- when the original TMDL was approved -- and using sophisticated water quality models, the updated TMDL will better account for the variety of point and nonpoint sources of phosphorus in the Lake's 285 square mile watershed.

The following table lists sources of phosphorus in Onondaga Lake that are included in the updated TMDL. Click the links to visit DEC webpages with general information about individual sources (not specific to Onondaga Lake).

Sources of Phosphorus in Onondaga Lake
Point Sources Nonpoint Sources
Wastewater treatment plants Stormwater runoff
Combined sewer overflows (CSO) Agriculture runoff
Municipal Separate Storm Sewer Systems (MS4) Household septic system
Construction & industrial stormwater discharges Natural sources
Concentrated Animal Feeding Operations (CAFO)

Onondaga Lake Background Information

Pollution control efforts, including upgrades to the Metropolitan Syracuse Wastewater Treatment Plant (METRO), have greatly improved water quality in Onondaga Lake and ongoing cleanup work is addressing contamination left over from decades of industrial pollution. In fact, phosphorus levels in Onondaga Lake met the statewide guidance value of 0.02 mg/L in 2008 and 2009. Improvements to METRO have decreased ammonia loading enough that the Lake is meeting the ammonia standard.

Despite the substantial gains made so far in Onondaga Lake, much work remains. For example, phosphorus levels during the 2010 summer growing season exceeded the guidance value. DEC expects the updated TMDL to help the Onondaga Lake Partnership develop methods for meeting the phosphorus guidance value, while continuing the recovery process.

In addition to phosphorus and ammonia, other pollutants that negatively affect water quality in Onondaga Lake include dioxins, mercury, PCBs and pathogens.

The dioxins, mercury and PCBs left over from years of industrial pollution are being addressed by the cleanup work at the Onondaga Lake Superfund Site. Pathogens enter the Lake when combined sewer overflows (CSOs) allow untreated waste to flow into the Lake and its tributaries. The 1998 Amended Consent Judgment required Onondaga County to control and reduce CSOs. DEC expects the CSO control project to help address the pathogen pollution in Onondaga Lake.

Onondaga Lake Timeline

The following timeline describes a few important events related to the phosphorus TMDL:

  • In 1988, Atlantic States Legal Foundation (ASLF), joined by DEC, filed a lawsuit against Onondaga County for violations of the federal Clean Water Act and the New York State Environmental Conservation Law. A judgment resulted, requiring Onondaga County to perform a series of studies to determine if the wastewater treatment performance at METRO could be improved with advanced treatment techniques. Other studies focused on advanced treatment techniques to reduce pollutants from combined sewer overflows in the area.
  • By 1996, Onondaga County determined that advanced treatment techniques would improve METRO's performance. A plan addressing improvements to METRO and the CSOs was submitted to ASLF and DEC early that year.
  • In 1998, ASLF, DEC and Onondaga County reached an agreement, known as the Amended Consent Judgment (ACJ), on a timeline for the County to implement the improvements identified in 1996.
  • Also in 1998, DEC developed a phosphorus TMDL that required reductions in phosphorus inputs, focusing on METRO and CSOs, to achieve a 0.02 mg/L level of phosphorus in the Lake.
  • On June 29, 2012, EPA approved an update the 1998 phosphorus TMDL. The revision used data gathered by DEC and Onondaga County, which monitor Onondaga Lake, its tributaries, and METRO. The revision also incorporated lake and watershed models supported by the Onondaga Lake Partnership to help identify and estimate phosphorus loads from all sources in the Onondaga Lake watershed.

    Note: The 1998 Amended Consent Judgment originally set a deadline of January 2009 to update the phosphorus TMDL. In 2009, a federal judge moved the deadline to December 31, 2011. The deadline has since been extended to June 30, 2012.