In the Energy Policy Act of 2005, Congress clarified that storm water discharges from field activities associated with E&P operations, including construction activities, are exempt from NPDES permitting requirements absent a contaminated discharge. The next year, U.S. EPA completed a rulemaking codifying that statutory exemption in its regulations; and further establishing an exemption for storm water discharges containing sediment only, finding that such discharges did not constitute a violation of a water quality standard.
122.26(a)(2) The Director may not require a permit for discharges of storm water runoff from mining operations or oil and gas exploration, production, processing or treatment operations or transmission facilities, composed entirely of flows which are from conveyances or systems of conveyances (including but not limited to pipes, conduits, ditches, and channels) used for collecting and conveying precipitation runoff and which are not contaminated by contact with or that has not come into contact with, any overburden, raw material, intermediate products, finished product, byproduct or waste products located on the site of such operations.
122.26(e)(8) For any storm water discharge associated with small construction activity identified in paragraph (b)(15)(i) of this section, see 122.21(c)(1). Discharges from these sources, other than discharges associated with small construction activity at oil and gas exploration, production, processing, and treatment operations or transmission facilities, require permit authorization by March 10, 2003, unless designated for coverage before then. Discharges associated with small construction activity at such oil and gas sites require permit authorization by June 12, 2006.