When the DRBC was created in 1961, little or no dissolved oxygen (DO) was present in the Delaware River Estuary from Wilmington to Philadelphia for periods of up to six months each year.

To combat this serious challenge, DRBC in 1967 established designated aquatic life uses and associated numerical water quality criteria necessary to protect those uses.

The aquatic life designated use in this part of the estuary was set as "maintenance" (survival) of resident fish and movement of migratory fish through these waters to and from spawning areas.

Significant improvements in DO levels have occurred throughout this stretch of river since 1967. By the late 1980s, over one billion dollars had been spent on improving wastewater treatment facilities throughout the basin, which benefited communities along the river and strengthened fish populations.

Today, the Delaware River Estuary supports resident fish and migratory fish populations.

But, we know that the early life stages of estuarine fish species are generally more sensitive to DO levels than are the adults living in the river stretches or just passing through these waters to reach spawning areas. 

It's time for the next chapter. Can the water quality be improved in this section of the estuary to better support reproduction and juvenile fish populations, as well as the endangered Atlantic sturgeon? 

In September 2017, the DRBC approved a resolution recognizing the significant water quality improvements in the Delaware River Estuary that have occurred and affirming that continued improvement is an important goal.

View Resolution 2017-4 (pdf)

View Comment and Response Document regarding Resolution 2017-4 (pdf)

View News Release

Resolution 2017-4 also provides for a formal study to determine the appropriate designated use for a 38-mile stretch of the tidal Delaware River and to provide data and information to establish revised water quality criteria to protect that use.

This stretch of river, from Wilmington, Del. to just above the Tacony-Palmyra Bridge (connecting Phila. and N.J.), includes DRBC Water Quality Zones 3, 4, and the upper portion of Zone 5.

View Map of DRBC Water Quality Zones (pdf)

View Project Fact Sheet (pdf)

The September 2017 Resolution provides for scientific and technical studies to be performed for the following purposes:

• To conduct additional field studies of the occurrence, spatial and temporal distribution of all life stages of important resident and migratory fish species that utilize the estuary;
  
  
• To determine the DO requirements of these fish species and the oxygen-depleting nutrient loadings from point (end-of-pipe) and non-point (runoff) sources that can be discharged into the tidal river while maintaining the DO levels in the water;
  
  
• To conduct an analysis to determine the attainability of DO requirements and water quality standards that would result in an upgrade in the designated aquatic life use in this 38-mile section of the river, including technical, social and economic factors; and
  
  
• To identify and evaluate opportunities for early action to reduce discharges of oxygen-depleting wastes to this stretch of river in the short term.
  
  

To support these studies and the development of the eutrophication model, lots of monitoring is needed.

Collecting water samples to look at light extinction data.	Nutrient monitoring at the Calhoun St. Bridge (Delaware River).	Nutrient monitoring at Darby Creek, a Delaware River tributary.	Nutrient monitoring at the Falls Bridge (Schuylkill River).	Collecting water samples to study primary productivity.

DRBC is leading this groundbreaking effort through a collaborative process informed by an Expert Panel of scientists and engineers and in close consultation with its Water Quality Advisory Committee, a group representing state and federal co-regulators, NGO's, academic institutions, municipal and industrial dischargers and water purveyors.

Once the study is complete, the resolution directs the initiation of a formal DRBC rulemaking process to revise the designated aquatic life uses consistent with the results of these scientific and technical studies, as well as with the federal Clean Water Act.

The Commission will issue a final rule and an implementation strategy, with the timeframe dependent on the availability of resources to fund the effort.

In September 2020, at their 3Q Business Meeting, the Commissioners approved a Resolution for the Minutes that modified the schedule adopted by Resolution 2017-4. The change to the schedule was necessary in light of COVID-19-related mitigation measures that affected monitoring efforts, as well as funding constraints.

View Resolution for the Minutes adopted September 10, 2020 (pdf 40 KB)

It is important to note that while the work is ongoing, lots of progress has been made to date, including:

• Input obtained from an Expert Panel on modeling the water quality impacts of nutrient loadings;

• Research on the dissolved oxygen requirements of key sensitive species completed;

• Ambient nutrient monitoring and primary productivity and algal speciation studies conducted to support model calibration;

• Development of a hydrodynamic and eutrophication model;

• Identification and evaluation of the capital and operating costs required for twelve wastewater treatment plants to implement technologies for achieving higher levels of dissolved oxygen; and

• Evaluation of the physical, chemical, biological, social and economic factors affecting attainment of uses.

Check out the reports and presentations archive sections to learn more.

• Nitrogen Reduction Cost Estimation Study: Final Summary Report (pdf 10 MB; this report was submitted to the DRBC by Kleinfelder, Inc., in January 2021)
  
  
• Report to DRBC on Concentrations of Nutrients and Chlorophyll-a and Rates of Respiration and Primary Production in Samples from the Delaware River Collected in May and July 2019 (pdf 1 MB; this report was submitted to the DRBC by the Horn Point Laboratory, University of Maryland; revised Sept. 2020)
  
  
• Report to DRBC on Concentrations of Nutrients and Chlorophyll-a and Rates of Respiration and Primary Production in Samples from the Delaware River Collected in May and July 2018 (pdf 740 KB; this report was submitted to the DRBC by the Horn Point Laboratory, University of Maryland; revised Feb. 2019)
  
  
• A Review of Dissolved Oxygen Requirements for Key Sensitive Species in the Delaware Estuary (pdf 615 KB; this report was submitted to the DRBC by the Academy of Natural Sciences in November 2018)
  
  
• A Methodology for Evaluating Dissolved Oxygen Requirements of Species in the Delaware Estuary (pdf 244 KB; this report was submitted to the DRBC by the Academy of Natural Sciences in March 2018)
  
  
• Existing Use Evaluation for Zones 3, 4, & 5 of the Delaware Estuary Based on Spawning and Rearing of Resident and Anadromous Fishes (pdf 8.3 MB; September 2015)
  
  
• Report to DRBC on Concentrations of Nutrients and Chlorophyll-a and Rates of Respiration and Primary Production in Samples from Delaware Bay Collected in May and July 2014 (pdf 2 MB; this report was submitted to the DRBC by the Horn Point Laboratory, University of Maryland in May 2015; revised Jan. 2019)

• Analysis of Attainability Part I: A Strategy to Determine Potential Designated Uses in the Delaware Estuary (pdf 1.9 MB; presentation given at the PDE Science and Environmental Summit, March 2021)
  
  
• Analysis of Attainability Part II: Linking Aquatic Life Uses with Dissolved Oxygen Condition in the Delaware River Estuary (pdf 1.2 MB; presentation given at the PDE Science and Environmental Summit, March 2021)
  
  
• DRBC Resolution for the Minutes: Sept. 2020 - Revised Schedule for Aquatic Life Designated Use Project (pdf 620 KB; presentation given at the joint WQAC/Expert Panel Meeting, Oct. 2020)
  
  
• Expert Panel Report to DRBC's WQAC (pdf 4 MB; presentation given at the joint WQAC/Expert Panel Meeting, Oct. 2020)
  
  
• Studies to Determine the Attainability of Aquatic Life Uses and Associated DO Conditions in the Urbanized Portion of the Delaware Estuary (pdf 2.4 MB; given at the Delaware Watershed Research Conference, Oct. 2020)
  
  
• A Fishable, Swimmable (and Drinkable) Delaware River Estuary (pdf 6.7 MB; given at the 8th Annual Delaware River Watershed Forum, Sept. 2020)
  
  
• Status Update: Aquatic Life Designated Use Program (pdf 890 KB; given to the WQAC on 7/28/20)
  
  
• Nutrient Monitoring 2020 (pdf 580 KB; given to the MACC on 5/12/20)
  
  
• "Analysis of Attainability": A Strategy to Determine Highest Attainable Dissolved Oxygen Condition (pdf 1.3 MB; given to the WQAC on 4/30/20)
  
  
• Eutrophication Model Development Monitoring (pdf 1.2 MB; given to the MACC on 12/18/19)
  
  
• Meeting of the Model Expert Panel with DRBC Staff (pdf 2.7 MB; given to the WQAC on 12/5/19)
  
  
• Update given at the WQAC Meeting, November 2019 (pdf 2 MB) 
  
  
• Update on Engineering Evaluation and Cost Estimates Contracted Work (pdf 1.5 MB; given at the Delaware Watershed Research Conference, November 2019)
  
  
• Modeling Eutrophication Processes in the Delaware Estuary to Link Watershed Efforts to Control Nutrient Impacts (pdf 1.6 MB; given at the Delaware Watershed Research Conference, November 2019)
  
  
• Eutrophication Model Development Monitoring Updates 2019 (pdf 736 KB; given to the MACC on 6/17/19)
  
  
• Tributary Ultimate BOD Monitoring (pdf 338 KB; given to the MACC on 6/17/19)
  
  
• Other DRBC Monitoring Surveys (pdf 330 KB; given to the MACC on 6/17/19; see light extinction and primary productivity slides) 
  
  
• Update on Eutrophication Model Development (pdf 374 KB; given to the WQAC on 5/14/19)
  
  
• Additional Review of Existing DO Data (pdf 2.2 MB; given to the WQAC on 5/14/19)
  
  
• Meeting of the Model Expert Panel with DRBC Staff - A Report to the WQAC (pdf 4 MB; this presentation was given to the WQAC on 3/20/19)
  
  
• The Next Chapter in the Story of Restoring Clean Water to the Delaware River Estuary (pdf 2.4 MB; given at the AWRA Annual Conference, November 2018)
  
  
• Dissolved Oxygen, Aquatic Life Uses, and the Delaware Estuary (pdf 2.2 MB; given at the WRADRB Annual Fall Conference, November 2018)
  
  
• Updating Major Wastewater Treatment Infrastructure for Delaware Estuary Aquatic Life Uses: Technical, Economic, and Social Impacts (pdf 2 MB; given at the Delaware Watershed Research Conference, November 2018)
  
  
• Modeling Eutrophication Processes in the Delaware Estuary to Link Watershed Efforts to Control Nutrient Impacts (pdf 1.6 MB; given at the Delaware Watershed Research Conference, November 2018)
  
  
• Eutrophication Model Development Monitoring 2018 (pdf 1.2 MB; given at the March 29, 2018, WQAC Meeting)
  
  
• Additional Monitoring Evaluation for Delaware Estuary Point Discharges (pdf 1 MB; presented at the August 2017 WQAC Meeting)
  
  
• DRBC to Review Aquatic Life Uses in Delaware River Estuary in Recognition of Improved Water Quality (pdf 1 MB; presented at the April 7, 2017 public hearing)

Resolution 2017-4 (pdf)

Resolution 2018-6 (pdf)

Resolution for the Minutes adopted September 10, 2020 (pdf)

Resolution 2021-5 (pdf)