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David Croxton U.S . Environmental Protection Agency Watershed Unit Manager– EPA Region 10

Incorporating Climate Change Adaptation in EPA Region 10 Programs : An example based on a newly initiated pilot in the Office of Water and Watershed’s Total Maximum Daily Load program. David Croxton U.S . Environmental Protection Agency Watershed Unit Manager– EPA Region 10.

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David Croxton U.S . Environmental Protection Agency Watershed Unit Manager– EPA Region 10

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  1. Incorporating Climate Change Adaptation in EPA Region 10 Programs: An example based on a newly initiated pilot in the Office of Water and Watershed’s Total Maximum Daily Load program David Croxton U.S. Environmental Protection Agency Watershed Unit Manager– EPA Region 10

  2. What is a TMDL? • A Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a pollutant that a water body (or segment) can receive and still meet the state/tribe’s water quality standards. • TMDLs are required by the Clean Water Act when a water body’s designated uses are determined to be impaired or threatened. • The pollutants causing or expected to cause the impairment are what are limited under a TMDL.

  3. What is a TMDL? (cont’d) A TMDL is the sum of the following: • Waste load allocation (WLA). Total amount of the pollutant from existing point sources (e.g., sewage treatment plant, industrial facility, stormwater). • Load allocation (LA).Total amount of pollutant from existing nonpoint sources and natural background (e.g., farm runoff, atmospheric mercury). • Margin of safety (MOS).Expressed as an explicit factor (e.g., percent of total, such as 10%) or an implicit factor (e.g., conservative assumption in modeling).

  4. Pilot Approach Underway • Will select a TMDL (or two) based on suggested criteria: • Timing of model development (i.e., so that new thinking can be incorporated in next six months) • Tribal involvement (i.e., clear role for EPA) • Watershed is in a location where analyses of potential changes have been conducted (e.g., vulnerability assessments) • Connection with other priorities (e.g., salmon recovery, Puget Sound) • Identify commonly occurring variables that relate to TMDL assumptions in models, analyses (e.g., T, flow) • Coordinate with EPA Region 1 on Lake Champlain phosphorus TMDL being revised to consider climate change.

  5. From Washington Technical Advisory Group Built Intrastructure Report (Dec. 2010) – Appendix C

  6. What will be Success for this Pilot? Overall our goal is to determine the science needs to support potential future changes into TMDL analyses. • Learn/adapt • Begin with one program to learn which impacts are most relevant and identify knowledge gaps; adapt this process for other programs • Identify needed tools, data sources, models, etc., and where they are available • Federal partnerships in the region, e.g., C3, will be useful • Climate Science Center and Climate Decision Support Center, Landscape Conservation Cooperatives • Identify policy issues and decisions

  7. Potential Policy Issues • Is climate change part of “background” conditions that aren’t assigned to any source category to address (e.g., lower flows)? • How much can the “margin of safety” be used to account for climate change uncertainty versus uncertainty of the models themselves? • Can /should we leverage more stringent limits or move to watershed-scale permits for point sources, to get more investments in green infrastructure in the watershed?

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