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The Aquaduct - Summer 2011

  NJDEP Adopts Changes to its Nutrient Regulations


By Thomas W. Amidon, Senior Associate, Omni Environmental, LLC.


The New Jersey Department of Environmental Protection (NJDEP) has been active over the last couple of years in proposing and adopting changes to its nutrient criteria and the manner in which it assesses nutrient impacts.  Here is a quick summary of activities.


Nutrient Criteria Enhancement Plan – NJDEP published a draft Nutrient Criteria Enhancement Plan (NCEP) in January 2009, which it finalized in April 2009.  The NCEP summarized NJDEP’s overall strategies in terms of nutrient regulation, and signaled its intent to address actual use impairments rather than regulating to arbitrary nutrient levels. 


Integrated Water Quality Monitoring and Assessment Methods – NJDEP proposed a draft 2010 Integrated Water Quality Monitoring and Assessment Methods Document (a.k.a. Methods Document) in April 2009, followed by a revised draft 2010 Methods Document in December 2009.  The Methods Document summarizes the approaches the Department proposes to use to evaluate designated use attainment, including the methodology for assessing nutrient impacts and the applicability of the instream numeric phosphorus criterion for freshwaters.  NJDEP finalized is 2010 Methods Document in September 2010, formalizing significant changes to its nutrient assessment methodology.


Surface Water Quality Standards (SWQS) – NJDEP proposed amendments to its nutrient criteria and policies in April 2009; these were revised and re-proposed in December 2009.  The proposed changed to nutrient policies and criteria were adopted in December 2010 and are now incorporated within the SWQS.


Here are a few of the regulatory improvements made by NJDEP relating to the manner in which it assesses nutrient impacts:

  • The 2010 Methods Document now states unequivocally: “The Department believes that cause/response relationships are better indicators of adverse nutrient impacts on the aquatic ecosystem than an assessment of the in-stream concentration of total phosphorus alone.”
  • The 2010 Methods Document assesses nutrient impacts only when aquatic life use impairment has first been confirmed independent of nutrients.  NJDEP begins its assessment of nutrient impacts with diurnal dissolved oxygen measurements, and applies periphyton density measurements as a seasonal average and only when the dissolved oxygen data are inconclusive. 
  • NJDEP formalized its nutrient policy as a narrative nutrient criteria, and clarified the language to make it clear that changes in aquatic ecosystems or diurnal DO swings must be deleterious in order to be considered a contravention of the narrative nutrient criteria. 

NJDEP has signaled its intent to propose additional revisions in the future so that the numerical phosphorus criteria are no longer expressed as not-to-exceed values. 


More information on NJDEP’s initiatives relating to nutrient regulation can be found here:

Nutrient Criteria Enhancement Plan:


Revised SWQS:  


Final 2010 Methods Document:  



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