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

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.

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).

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.

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

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

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?