Notes on Application of EPAs 304(a) Aquatic Life Saltwater D.O. - - PowerPoint PPT Presentation

Office of Research and Development

Notes on Application of EPA’s 304(a) Aquatic Life Saltwater D.O. Criteria to NH coastal waters

James Hagy and Brenda Rashleigh US EPA Office of Research and Development (ORD) December 5, 2019

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The views expressed in this presentation are those of the author(s) and do not necessarily represent the views or the policies of the U.S. Environmental Protection Agency.

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EPA’s Aquatic Life Criteria Guidance is one reference point for D.O. criteria in NH

Acute threshold (CMC) - D.O. below this level causes acute mortality of juveniles and adults Chronic threshold (CCC) - D.O. above this level expected to protect aquatic life

Recruitment curve – effects

• n sensitive larvae

Duration

• “Virginian Province Approach” is EPA’s

Saltwater Aquatic Life D.O. criteria guidance.

• Acute (2.3 mg/L) and Chronic (4.8

mg/L) criteria are based on lab exposure tests for most sensitive juveniles and adults.

• In practice, states have made

adjustments for local species, temperature, or other factors.

• New science has identified additional

considerations, such as interaction of low D.O. and low pH effects.

• EPA guidance also specifies that D.O.-

sensitive threatened and endangered species should be considered separately when criteria applies to habitat.

Three-part criteria approach in EPA guidance

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Larval Recruitment model estimates impairment of fish recruitment by low D.O.

• Larval recruitment model portion of

saltwater guidance utilizes life history and D.O. sensitivity parameters.

• Estimates overall impact of low D.O.
• n seasonal recruitment
• 6 resident species were evaluated as

requested by NHDES

• Used LC50 = 3.15 mg/L for all species
• Long spawning season length is

relevant for exposure of Atlantic sturgeon larvae to low oxygen.

Fish Species Start day Spawning season length (days) Larval Development Time (days) Atlantic sturgeon 127 90 28 Shortnose sturgeon 118 45 12 Alewife 120 45 30-40 Blueback herring 125 61 30 American shad 136 75 2-7 Rainbow smelt 95 61 30-45

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Existing D.O. levels at Lamprey River may impact Atlantic sturgeon recruitment

• Most spawning is estimated to
• ccur before low D.O. events.
• EPA guidance targets <5%

impairment.

• With uniform spawning,

Atlantic sturgeon at Lamprey River overlap low D.O. events, suggesting possible recruitment impacts.

• Future shift toward earlier low

D.O. events or extended spawning could cause greater

• verlap and larger effects.

1 2 3 4 5 6 200 400 600 800 1000 1200

D.O. (mg/L) Cohort Size Month

F M J A M J J A S O N D CCC

Fish Species GRBGB GRBSQ GRBLR Atlantic sturgeon 7.5% Shortnose sturgeon Alewife Blueback herring American shad Rainbow smelt Spawning Activity

Low D.O. Events

D.O. vs. pH in D.O. Exposure Tests differed from D.O. vs. pH in natural waters

• EPA tests in 1990s

maintained ambient pH.

• In natural waters, low pH

and low D.O. occur together.

• Recent studies show adverse

effects of low pH and D.O. can be additive.

• Laboratory thresholds may

underestimate D.O. levels needed to prevent impacts in natural waters subject to co-occuring low pH.

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Narragansett Bay Long Island Sound EPA Tests

6.9 7.1 7.3 7.5 7.7 7.9 8.1 8.3 2 4 6 8 10

DO (mg/L) pH

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Question or Comments?

James Hagy US EPA / Office of Research and Development Center for Environmental Measurement and Modeling hagy.jim@epa.gov Brenda Rashleigh US EPA / Office of Research and Development Center for Public Health and Environmental Assessment rashleigh.brenda@epa.gov