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2020 303(d) Listing and Delisting Methodology Clarifications

Requesting approval to proceed to the EMC for the proposed clarifications to the 2020 303(d) Listing and Delisting Assessment Methodology Outline. This document outlines the decision-making process for including or removing waters from the impaired waters list.

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2020 303(d) Listing and Delisting Methodology Clarifications

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  1. 2020 303(d) Listing and Delisting Methodology WQC and EMC, Sept 11, 2019 Pam Behm, DWR Modeling and Assessment Branch Department of Environmental Quality

  2. Purpose Request approval to proceed to the EMC for approval of the proposed clarifications to the 2020 303(d) Listing and Delisting Assessment Methodology

  3. Outline • Statute • History • 2020 Methodology Updates

  4. Statute 143B-282(c): The EMC shall implement the provisions of subsections (d) and (e) of 33 U.S.C. § 1313 by identifying and prioritizing impaired waters

  5. Some Terminology • 303(d) List – Refers to section of Clean Water Act (CWA). List of impaired waters where a TMDL or alternative management action is needed • TMDL – Total Maximum Daily Load – establishes maximum amount of pollutant in a waterbody and sets limits on sources • Assessment Unit (AU) – spatial description of an assessed water • Excursion – individual exceedence of a standard • Exceedence (Rate) – # of excursions, expressed as a number or a percent • Integrated Report – combines CWA sections 305(b) and 303(d), list of all assessed waters

  6. What is the 303(d) List? • List of impaired waters where a TMDL or alternative management action is needed • Established by Section 303(d) of the Clean Water Act • Public review and comment is required, minimum of 30 days • Due to EPA every even-numbered year on April 1 • EPA has final approval authority

  7. What is the 303(d) Listing and Delisting Methodology? • Documents decision making process for determining whether a water should be included OR removed from the 303(d) list • Required to submit to EPA, but EPA not required to approve • However, if EPA does not agree with a listing or delisting decision (which is based on the methodology), they can disapprove the 303(d) list

  8. What is the Integrated Report? • List of ALL assessed waters and assigned categories • Established by Sections 305(b) and 303(d) of the Clean Water Act • Not required to receive public comment • CWA requires submittal to EPA, but EPA does not approve/disapprove

  9. Integrated Reporting Categories 1 2 3 4 5 MC Meeting Criteria Data Inconclusive Exceeds Criteria (“impaired”) Integrated Report 305(b) Report DI NC Impaired Waters List EC 303(d) List

  10. 303(d) Assessment Procedures Data Window – 5 years: 2018 303(d): 2012-2016 2020 303(d): 2014-2018 2020 “New Data Years”: 2017-2018

  11. 303(d) Assessment Procedures Numerical criteria assessment (10% exceedance method with 90% statistical confidence), minimum of 10 samples Biological rating method used to assess benthic and fish community collections Pathogen criteria method to assess recreation standards Shellfish growing area assessment method to assess waters classified as “SA” Fish advice and advisories with fish tissue data method to assess fish consumption

  12. History - 2018 303(d) Assessment Changes • Changes were in response to EPA objections that held-up action, caused partial disapprovals in 2014 and 2016 • Added explicit delisting process • Added a process to evaluate small datasets • Balanced statistical criteria for meeting and exceeding decisions

  13. 2018 303(d) Results • EPA issued full approval of the 2018 303(d) list on May 22, 2019 • 50-day turnaround from submittal • 2nd fastest turnaround the state has ever received • 1st unconditional approval the state has received

  14. Methodology Updates for 2020 • Based on public comments received during 2018 review: • Added a section on assessment unit (AU) delineation* • Addressed an unintended consequence for waters not previously listed with greater than 3 excursions in new data years • Added delisting process for old total metals listings* * Not really a change, but is added to the 2020 303(d) Listing and Delisting Methodology based on public comment

  15. What is an Assessment Unit (AU)? • Spatial extent of a water quality “assessment” • Used for 303(d) / Integrated Reporting (IR) • Based on Classification Index Number • Concept of AU: • Represents an area where water quality is expected to be similar • Can have 1 or more monitoring station(s) Example: AU 9-23-14b: Cedar Creek (From SR 1008 to Cove Creek)

  16. What causes AU changes? • Monitoring stations are first assessed individually • If there are differences in resulting assessment (where there are multiple stations in 1 AU), AU is split or divided • Due to changes in water quality, or • New stations have been added, or • Methodology changes have impacted assessment decisions • Applied statewide • This has been the procedure since 2004

  17. Why is this method used? • Consistent with “not to exceed” standards Chlorophyll-a: not greater than 40 µg/l for lakes, reservoirs, and other waters subject to growths of macroscopic or microscopic vegetation • Adds transparency • Avoids having to make arbitrary decisions • Avoids having to impair or rate inconclusive larger areas than necessary • Acknowledges where waters are meeting criteria • Acknowledges where there are “hot spots”

  18. Assessment Unit Delineation • Discussed in detail in DWR’s Response to Comments from 2018 review (https://files.nc.gov/ncdeq/Water%20Quality/Planning/TMDL/303d/2018/2018303d-DWR-Response-to-Comments-final.pdf, page 72) • Added section to methodology to explain process for “splitting” assessment units • Improves transparency

  19. For waters with: Greater than 10% exceedence/less than 90% statistical confidence in exceeding criteria • Previous language: Greater than 3 excursions in new data years leads to exceed criteria determination • Unintended impact: penalizes those who collect more frequent data • Fix: • Greater than 3 excursions in new data years with 90% confidence in exceeding criteria leads to exceed criteria determination • Impact estimate ~ 10 waters compared to about 15 in 2018

  20. For waters with: Greater than 10% exceedence/less than 90% confidence

  21. Delisting Process for Total Metals • New dissolved standards replaced old total metals standards in 2015. • DWR successfully delisted 41 waterbody/parameter combinations in 2018 • Process was not explicit in 2018 methodology • Waters will be delisted for old total metal listings when new data is available for assessment under new standards • No regulatory action (e.g. TMDL) taken on old listings until impairment is confirmed under new standard

  22. Delisting Process Added to Methodology For legacy total metals impairments, where total criteria were replaced with dissolved criteria in January 2015, DWR will delist assessments for total metals only when current dissolved metals data are available for assessment.

  23. Proposed Timeline • EMC approves clarifications to methods and receive comment on methods during 303(d) public review: November 2019 • Perform assessment: 4-5 months • 30-day public comment on 303(d) list: March-April 2020 • Clean Water Act due date: April 1, 2020 • Report to EMC with an information item: July 2020 • Submit to EPA: August 1, 2020

  24. Proposed Action Recommend approval to proceed to the EMC for approval of the proposed clarifications to the 2020 303(d) Listing and Delisting Assessment Methodology

  25. Thank You! Contact Information: Pam Behm 919-707-3687 pamela.behm@ncdenr.gov

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