Map of regional haze sources Regional haze has reduced scenic views in national parks and wilderness areas from an average of 140 miles down to 35-90 miles in the Western U.S. In 2010, we revised the regional haze State Implementation Plan (SIP) to identify key sources of air pollution and define a strategy to improve visibility in Washington's Class 1 areas.

The next plan — for the period 2018-2028 — is due to EPA by July 31, 2021. The documents listed below are part of developing that plan.

Regional haze State Implementation Plan revision

Pulp and paper mills


Glass manufacturing


Contact information

Colleen M. Stinson
Environmental Planner

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