2020 303(d) Listing Methodology Workgroup Kick-off meeting – September 14, 2018 CDPHE - C1A, 9-11 am
Agenda Time Agenda Topic Lead 9:00 am Introductions Skip Feeney 9:15 am 2020 Listing Methodology Workgroup Purpose Skip Feeney Scope/Introduce Topics All 9:30 am 10:00 am Lower Confidence Level Assessment of Iron, Skip Feeney / Sarah Manganese and Sulfate Wheeler 10:30 am Pollution vs Pollutant and M&E List Introductory Lorie Petersen Language in Regulation 93 10:50 am Adjourn 2 303(d) Listing Methodology
Introductions 3 303(d) Listing Methodology
Overview of Workgroup Regulation #93 • Section 303(d) of the Clean Water Act. – Requires states to identify waters where effluent limitations are not stringent enough to attain water quality standards. • 303(d) List of Impaired Waters. – Waterbodies exceeding standards and/or not attaining uses. • Monitoring and Evaluation List Waterbodies – where we suspect problems. • Approved through a rulemaking hearing every 2 years. 4 303(d) Listing Methodology
Overview of Workgroup 303(d) Listing Methodology • Framework for determining attainment. • Establishes listing requirements. • Explains: – the processes for adoption of LM and 303(d) List. – how data are assessed and interpreted. – how impairments are determined. – how priorities are established for TMDL development. • Revised every two years through a public workgroup process. • Approved through an administrative action hearing since 2003. 5 303(d) Listing Methodology
Work Group Administration Workgroup Chair: Skip Feeney skip.feeney@state.co.us 303.691.4928 Workgroup Coordinator: Caroline Byus caroline.byus@lrewater.com 303.455.9589 http://colowqforum.org/workgroup- 303d-listing-methodology.html 6 303(d) Listing Methodology
Overview of Workgroup Meeting Schedule October 16, 2018 1:00 - 3:00 pm CDPHE C1A – Topic 3 – How 303(d) and M&E listings are carried over when water body re-segmentation occurs. – Topic 4 - Update the Listing Methodology to remove the temperature excursion allowance for lakes and reservoirs. November 16, 2018 9:00 - 11:00 am CDPHE C1A – Wrap up on all topics and final adjustments to 2020 Listing Methodology. 7 303(d) Listing Methodology
Overview of Workgroup Important Dates 303(d) LISTING METHODOLOGY MILESTONE APPROXIMATE DATE 2 nd week in Jan. 2019 Draft proposal deadline 4 th week in Jan. 2019 Written comments due 3 rd week in Feb. 2019 Rebuttal comments due 4 th week in Feb. 2019 Revised proposal due March 11 th , 2019 Administrative Action Hearing (AAH) 8 303(d) Listing Methodology
Overview of Workgroup Ground Rules Mission: To achieve solutions to Colorado water quality issues through communication and understanding, balancing use and protection of the resource. Ground Rules: – Come to each meeting prepared for the scheduled discussion, e.g. having reviewed any relevant draft documents that have been circulated prior to the meeting. – Avoid personal attacks. Be respectful of others’ perspectives and responsibilities. – Respect the process by letting others know if differences remain that will be pursued in other venues. 9 303(d) Listing Methodology
Agenda Time Agenda Topic Lead 9:00 am Introductions Skip Feeney 9:15 am 2020 Listing Methodology Workgroup Purpose Skip Feeney 9:30 am Scope/Introduce Topics All Lower Confidence Level Assessment of Iron, Skip Feeney / Sarah 10:00 am Manganese and Sulfate Wheeler 10:30 am Pollution vs Pollutant and M&E List Introductory Lorie Petersen Language in Regulation 93 Adjourn 10:50 am 10 303(d) Listing Methodology
Update the Listing Methodology to remove the temperature excursion allowance for lakes and reservoirs • Until 2016, Regulation #31 allowed for excursions of both the dissolved oxygen (DO) and temperature standards if adequate refuge was available. • In 2016, the language that allowed for temperature exceedances, despite the presence of adequate refuge, was removed from the regulation. • The 2018 Listing Methodology still allows for temperature excursions and need to be updated. 11 303(d) Listing Methodology
Agenda Time Agenda Topic Lead 9:00 am Introductions Skip Feeney 9:15 am 2020 Listing Methodology Workgroup Purpose Skip Feeney Scope/Introduce Topics All 9:30 am 10:00 am Lower Confidence Level Assessment of Iron, Skip Feeney / Sarah Manganese and Sulfate Wheeler 10:30 am Pollution vs Pollutant and M&E List Introductory Lorie Petersen Language in Regulation 93 10:50 am Adjourn 12 303(d) Listing Methodology
Lower Confidence Limit Methodology for Secondary WS Standards • Background information – Mineral Creek COSJAF09 – Lower Confidence Limit Methodology – Water Supply Standards • Issue Summary / Example • Proposed action – Listing Methodology Language Changes 13 303(d) Listing Methodology
Background – 2018 303(d) List Assessment Background: • Assessment of Mineral Creek COSJAF09 indicated exceedance of the dissolved iron secondary water supply standard. • Animas River Stakeholders Group demonstrated attainment of iron utilizing the lower confidence limit methodology (Appendix B of the Listing Methodology). • Approved by Commission in 2018. • Division is proposing to expand approach for all similar cases. 14 303(d) Listing Methodology
Background – Lower Confidence Limit Methodology First developed to assess ambient-based standards • Ambient-based standards: – Water quality doesn’t meet standard(s) • Natural source • Irreversible man-induced cause • Define standard based on ambient (existing) water quality. For dissolved pollutants: – Chronic std= 85th percentile – Acute std= 95th percentile 15 303(d) Listing Methodology
Background – Lower Confidence Limit Methodology • Face value assessment approach. • Challenges: – Seasonal variation – Sampling and analytical error • Expected variation in data will lead to differing attainment conclusions. • Wanted to improve confidence that impairment conclusions are based on significant water quality change. 16 303(d) Listing Methodology
Background – Lower Confidence Limit Methodology • Ambient-based standards are now assessed with lower confidence limit (LCL) methodology. • Exceedance indicates impairment with 95% confidence. • 303(d) Listing Methodology Section IV.F, pg. 21. • Listing Methodology Appendix B. • Quantity of samples equates to a LCL percentile. • Compare LCL percentile of current data to ambient-based standard. 17 303(d) Listing Methodology
Background: Assessment of Iron, Manganese and Sulfate Water Supply Standards The least restrictive of the following two options apply: • Existing quality as of January 1, 2000; or • Table value criteria – Iron 300 ug/l (dissolved) – Manganese 50 ug/l (dissolved) – Sulfate 250 mg/l • Regulation 31.11(6) 18 303(d) Listing Methodology
Background: Assessment of Iron, Manganese and Sulfate Water Supply Standards How do we set the value for existing quality as of 2000? • Data from 1995-2009 from available data sources. • Compiled by segment. • Per segment, the 85th percentile of the concentration data is used to calculate the water quality as of the year 2000 value. • This value is compared to TVS to determine least restrictive value. • All of this information is stored in WS data library. 19 303(d) Listing Methodology
Issue Summary: • Existing quality as of the year 2000 value is created in similar fashion as an ambient-based standard. • Trying to capture conditions from a certain time period and protecting against conditions becoming worse in the future. • Variability in data used to set the standard and variability in data used to characterize ambient conditions. • Same challenge as assessing ambient-based standards. • Different assessment conclusion based on expected variation within the data. 20 303(d) Listing Methodology
Issue Summary: • 2018 303(d) Hearing - ARSG recommended that the division use the LCL approach for Fe, Mn and SO4 WS standards when 2000 is less restrictive. • Commission agreed that these WS standards are similar to ambient standards and so the LCL method is appropriate. Division’s proposal: Use the lower confidence limit approach for assessing Fe, Mn and SO4 water supply standards when existing quality from 2000 is the least restrictive value for assessment. 21 303(d) Listing Methodology
Real World Example Mineral Creek COSJAF09 Parameter Existing Quality as Current Water Number of Quality (85 th of 2000 Samples percentile) Dissolved Iron 3200 µg/L 3304.6 µg/L 73 Assessment conclusion: Impaired 22 303(d) Listing Methodology
Lower Confidence Limit Table • From Appendix B of the 2018 Listing Methodology. • 85 th percentile is used for secondary water supply assessments. • Sample size is 73. • The LCL is 0.766 which equates to the 76.6 th percentile. 23 303(d) Listing Methodology
Real World Example Mineral Creek COSJAF09 Existing Lower Confidence Limit Methodology Method Parameter Existing Current Water Number of Current Water Quality (85 th Quality (76.6 th (dissolved) Quality as of Samples 2000 percentile) percentile) Iron 3200 µg/L 3304.6 µg/L 73 3050.7 µg/L Assessment conclusion: Attains 24 303(d) Listing Methodology
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