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STATE OF WASHINGTON DEPARTMENT OF ECOLOGY P[) Ha% 47600 •Olympia, WA 98504-7600 •360-407-6000 711 h)r Waihingtem belay Service • Persons with a speech disahility can call 877-83.3-6341 January 17, 2007 Petition Criteria The process to get additional areas covered under the permits The factors Ecology will consider in evaluating municipal separate storm sewers include, but are not limited to, the factors listed below. Ecology's evaluation will be on a case by case basis, and in the exercise of its discretion Ecology may rely on other factors to evaluate municipal separate storm sewers. The factors listed below are provided to give potential petitioners guidance regarding the factors Ecology will typically consider, but are not intended to restrict Ecology's exercise of its discretion. Factor 1: Does the municipal separate storm sewer discharee stormwater to impaired or sensitive waters? Ecology will consider whether the municipal separate storm sewer discharges to impaired or sensitive waters that need protection to maintain or restore uses. • "Impaired waters" are Clean Water Act section 303(d) -listed water bodies. • "Sensitive waters" include public drinking water intakes and their designated protection areas; designated public swimming areas; shellfish beds; State - designated Outstanding Resource Waters; National Marine Sanctuaries; State Aquatic Reserves; and waters determined to be critical habitat for threatened or endangered species. Ecology will also consider whether stormwater management practices are likely to contribute to the necessary protective and/or restoration measures for the water body of concern, e.g. if the impairment is due to a constituent of concern in stormwater. Constituents of concern in stormwater typically include: arsenic, cadmium, copper, chromium, lead, zinc, heat, oil and grease, organic toxins, oxygen -demanding organics, nutrients, sediments, bacterial/viral agents and other pathogens. Factor 2: Is the municipal separate storm sewer a significant contributor of pollutants to waters of the United States? Ecology will consider whether the activities that take place in the municipal separate storm sewer contribute a loading of pollutants that are considered to be sufficient to cause or exacerbate the deterioration of receiving water quality or instream habitat conditions. This consideration will be based on best available science and readily available information. The types of information or metrics that may be considered and applied include, but are not limited to: • Water quality monitoring data; • Landscape metrics such as total impervious surface area, road network density, or number of stream crossings by roads; Modred Oclober 13, 2014