EPA Proposes Federal Water Quality Standards to Protect Fish Propagation in the Delaware River

January 18, 2024
Brenda H. Gotanda, Esq.
MGKF Special Alert - 2024 Federal Forecast

As we head into 2024, the United States Environmental Protection Agency (EPA) is seeking to establish federal water quality standards for certain zones of the Delaware River in Pennsylvania, New Jersey, and Delaware in order to increase protection of fish and aquatic life. In particular, EPA is proposing to add a new designated use of aquatic life propagation and to establish associated water quality criteria to raise the dissolved oxygen levels in the waterbody.  The proposed federal water quality standards would apply to the areas of Delaware River designated as Zone 3, Zone 4, and the upper portion of Zone 5, which stretches roughly from the Philadelphia, PA and Camden, NJ area down to Wilmington, DE (river miles 108.4 to 70.0).

On December 21, 2023, EPA published a proposed rule in the Federal Register to elevate the designated use of the covered waters from “maintenance” and ‘passage” of fish and other aquatic life to a designated use that includes “propagation” of resident and migratory aquatic life. EPA views propagation as the production, growth, and survival of early life stages of aquatic species that result in the addition of new individuals to the population. The proposal, if finalized, would also establish water quality criteria for dissolved oxygen that EPA believes are necessary to support propagation. According to EPA, it based the proposed new criteria on the oxygen needs of the most oxygen-sensitive fish species in the covered waters, the Shortnose Sturgeon and the Atlantic Sturgeon, both federally listed endangered species.

EPA’s regulatory action follows an Administrator’s Determination issued by EPA on December 1, 2022 in which it concluded that the broader designated use of “propagation,” and corresponding dissolved oxygen criteria to support that use, are necessary to meet the requirements of the Clean Water Act. EPA’s Determination was issued in response to a petition submitted by a group of non-governmental organizations (NGO) that sought to bypass an ongoing rulemaking process that was already underway at the Delaware River Basin Commission (DRBC). DRBC had adopted a resolution in 2017 (Resolution 2017-4) directing its staff to initiate a rulemaking process on propagation, but to first undertake necessary scientific and technical studies to determine what would be the highest attainable use and associated dissolved oxygen criteria. DRBC undertook a multi-year analysis that involved, among other things, 3-D water quality modeling and a series of studies to evaluate the physical, chemical, biological, social and economic factors affecting the attainment of uses. In September 2022, DRBC released its draft report entitled Analysis of Attainability: Improving Dissolved Oxygen and Aquatic Life Uses in The Delaware River Estuary. The NGO petition sought to put EPA in the lead on rulemaking. Following issuance of EPA’s Determination, DRBC suspended its own rulemaking process and deferred to EPA, stating that it will work with EPA and the affected states and stakeholders with respect to implementation of new standards.

In the proposed rule, EPA states that its proposed designated use of “protection and propagation of resident and migratory aquatic life” would apply in addition to any designated uses already established by the states for areas under their jurisdiction. According to EPA, this federally established designated use would apply in Pennsylvania and New Jersey, which do not already have propagation as a use in the zones but would not apply in Delaware since that state already has water quality standards that include propagation and apply to the waterbody.

EPA is proposing to establish federal dissolved oxygen water quality criteria that would replace existing criteria for the affected zones of the Delaware River in all three states. The proposed criteria, shown in Table 1 below, include magnitude, duration, and exceedance frequency elements that would be set for three distinct seasons. The magnitude element indicates the required minimum level of dissolved oxygen in the waterbody and the duration element indicates the time period over which dissolved oxygen levels are averaged for comparison with the magnitude percentage. The exceedance frequency element indicates how often each magnitude level can be exceeded during the season while still ensuring that the designated use is protected. EPA notes that a dissolved oxygen exceedance occurs when the oxygen level in the water is below the criterion value. EPA has proposed to use a single dissolved oxygen criterion value in two seasons (Spawning and Larval Development season and Overwintering season) and to use two individually applicable criteria (both levels must be attained) in the third season (Juvenile Development season).

Table 1: EPA’s Proposed Dissolved Oxygen Criteria



(Percent Oxygen Saturation)

Duration Exceedance Frequency

Spawning and Larval Development

(March 1 – June 30)

66% Daily Average

(12 Days Cumulative)

Juvenile Development

(July 1 – October 31)



Daily Average

Daily Average

(12 Days Cumulative)

(61 Days Cumulative)


(November 1 – February 28/29)

66% Daily Average

(12 Days Cumulative)

If finalized, the new standards may form the basis for new limits in NPDES discharge permits issued by the states to dischargers with a reasonable potential to exceed the new standards. However, EPA also notes that states may also consider alternative regulatory approaches for implementation such as the use of variances and permit compliance schedules where appropriate under the Clean Water Act.

EPA anticipates that additional pollution control technologies will be required at certain wastewater treatment plants to reduce effluent ammonia nitrogen concentrations and raise effluent dissolved oxygen concentrations in order to meet the new water quality standards. It has estimated annualized compliance costs to be over $137 million (applied over a 30-year period with a 3 percent discount rate) in total.

Noting that it is only proposing to establish federal water quality criteria addressing dissolved oxygen in specified zones, EPA recommends in its proposal that the states of Delaware, Pennsylvania and New Jersey undertake an evaluation to determine whether any aquatic life water quality criteria for other pollutants or parameters should be added or revised for the specified zones or other zones of the Delaware River in order to ensure they are sufficient to support the designated use that EPA establishes as part of a final rulemaking.

EPA is accepting comments on the proposed rulemaking through February 20, 2024.

If you have questions concerning the proposal or are seeking assistance in preparing comments, please contact Brenda Gotanda at 484-430-2327.