The Raritan River Basin encompasses 1,105 square miles in north-central New Jersey draining to the Raritan Bay at Perth Amboy. The study area for the Raritan River Total Maximum Daily Load Report and Watershed Protection Plan focuses on the non-tidal portion of the watershed, which includes Watershed Management Area (WMA) 8 (North and South Branch Raritan) (excluding the watershed of Spruce Run Reservoir), part of WMA 9 (Lower Raritan, South River, and Lawrence) and all of WMA 10 (Millstone). The study area (830 square miles) is shown in Figure 1.
The New Jersey 2004 Integrated Water Quality Monitoring and Assessment Report identified 30 waterbodies in the non-tidal Raritan basin as high priority for TMDL development to address phosphorus impairments.
DEP funded a basin-wide study to identify in-stream critical locations and determine the pollutant load reductions needed to attain the total phosphorus, dissolved oxygen, pH, and total suspended solids criteria specified in the Surface Water Quality Standards for the multiple stream classifications present in the non-tidal Raritan River basin. The TMDL study was conducted by Kleinfelder/Omni and resulted in two reports, one summarizing the monitoring work that served as the foundation for the modeling and the other presenting the model development and outcomes.
These studies were reviewed by the Rutgers New Jersey EcoComplex TMDL review panel which found the model to be appropriate for use in developing the TMDLs. Using these studies, DEP addressed 42 assessment unit/impairment combinations for total suspended solids and total phosphorus (as well as 3 for pH and one for dissolved oxygen), as described in the TMDL report (2014), listed in Appendix A and shown in Figure 2.
Figure 2
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The Kleinfelder/Omni reports (2005, 2013) describe the development of integrated hydrodynamic and water quality models used to develop the TMDLs. The water quality model used was Water Quality Analysis Simulation Program 7.1 (WASP 7.1), and the hydrologic model used is called HydroWAMIT. The latter component provides hydrodynamic and nonpoint source inputs to WASP 7.1.
Due to the large spatial extent of the watershed, the non-tidal Raritan River basin was modeled by dividing the basin into five sub-basins, with each sub-basin having its own model: North and South Branch Raritan River; Upper Millstone River; Stony Brook; Beden Brook/Lower Millstone River; and Mainstem Raritan River. The watersheds of the Spruce Run Reservoir, Round Valley Reservoir, and the Delaware and Raritan Canal were not modeled as part of this study, but were included as boundary inputs.
The models were constructed and calibrated for nutrients, dissolved oxygen and total suspended solids, accounting for critical conditions and seasonal variations. The linked models were used to simulate water quality and flow in the non-tidal Raritan River under various scenarios and to calculate the pollutant load reductions needed to meet the critical water quality end point that would ensure attainment of Surface Water Quality Standards for the subject parameters throughout the study area.
The TMDL report for the non-tidal Raritan River watershed, approved by EPA on May 9, 2016, is applicable to attaining the Surface Water Quality Standards for the 46 assessment unit/pollutant combinations addressed by the TMDL.
Additionally, in 2018 a Raritan River Watershed Protection Plan was developed by DEP that extends the coverage of the TMDL implementation plan, with some additional actions, as the means of maintaining water quality in the 66 assessment units where Surface Water Quality Standards for total phosphorus and/or total suspended solids were attained according to the 2014 Integrated Report (listed in Table 1). A combination of regulatory and non-regulatory tools that result in reductions in total phosphorus and total suspended solids loading and lead to future attainment of Surface Water Quality Standards in the TMDL Hydrologic Unit Codes, as well as assuring continued protection of the Hydrologic Unit Codes which currently attain criteria for total phosphorus and/or total suspended solids will further help this “Feature TMDL” and watershed.
DEP is moving science into action in the Barnegat Bay watershed. The Barnegat Bay Restoration, Enhancement, and Protection Strategy is built upon the data, modeling results, and research of the Phase One Barnegat Bay Ten-Point Plan that was announced in 2010.
The strategy provides four major components that specify short term, mid-term, and long term actions and objectives based on the findings from the Ten-Point Plan. The four major components are restoration, enhancement, protection, and assessment.
Work on a Barnegat Bay-related TMDL will occur as part of the Restoration section of the Strategy. For more information, visit the Barnerget Bay page.
For more information, please contact Kimberly Cenno, Bureau Chief, Bureau of Environmental Analysis, Restoration and Standards at (609) 633-1441.
