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Supreme Court: Polluted water flowing in improved waterway is not a regulated ‘discharge’

Last month the United States Supreme Court issued a key decision defining what is the “discharge of a pollutant” under the federal Clean Water Act. The decision has broad economic and wastewater management implications in Idaho and throughout the West.

In Los Angeles County Flood Control District v. Natural Resources Defense Council, the court held that the flow of water from improved concrete-lined portions of a navigable waterway (the Los Angeles and San Gabriel rivers) into unimproved portions of the same waterway does not qualify as a discharge of pollutants under the Clean Water Act.

The Supreme Court reversed a previous Ninth Circuit Court of Appeals ruling holding the Los Angeles County Flood Control District liable for alleged pollutant discharges. In the Ninth Circuit’s view, the detection of polluted water at monitoring stations in unimproved river segments below the concrete-lined sections of these rivers established the discharge.

Environmental groups brought the L.A. County case, alleging that the district was discharging polluted and untreated stormwater collected by the district’s municipal separate storm sewer systems (also known as MS4s) in violation of the district’s National Pollutant Discharge Elimination System permit. It was undisputed that water quality monitoring stations on unimproved sections of the Los Angeles and San Gabriel rivers, downstream from the concrete-lined sections of the rivers, measured repeated exceedances of the water quality standards in the district’s NPDES permit. However, numerous dischargers other than the district also put wastewater into the rivers upstream of the monitoring stations. The district asserted that there was no evidence as to the source of the water quality violations.

The Clean Water Act defines the term “discharge of a pollutant” to mean “any addition of any pollutant to navigable waters from any point source.” The Supreme Court stated that under the common understanding of the word “add,” no pollutants are “added” to a water body when water merely is transferred from one portion of that water body to another portion of the same water body. In a previous case from 2004, South Florida Water Management District v. Miccosukee Tribe, the court held that polluted water removed from a canal, transported through a pump station, and then deposited into a nearby reservoir would be a discharge of pollutants under the Clean Water Act only if the canal and the reservoir were “meaningfully distinct water bodies.” In this instance, the court stated, following from Miccosukee, that no discharge of pollutants occurs when water merely flows from one portion of the water body to another.

The L.A. County decision demonstrates that despite the generally broad reach of the Clean Water Act, not every water transfer or discharge amounts to a regulated “discharge of a pollutant.” Also, in situations where different wastewater flows or discharge streams may be commingled or joined in the same waterway or water body, the L.A. County decision supports the federal Environmental Protection Agency’s previously adopted view that the mixing of such flows does not create a separate discharge or regulated event.

Under EPA’s perspective, because the different discharge streams existed prior to their becoming mixed or commingled, that mixing would not alter the respective permitted or exempt status of the separate discharges once they are commingled. In Idaho, EPA is the NPDES permitting authority because Idaho does not have a state-delegated Clean Water Act permitting program.

The L.A. County case’s conclusion is an important consideration for Idaho MS4 operators, including many Idaho cities, counties and highway districts. There are 15 different MS4 permits for the state’s larger metropolitan areas, all state highways and roads, and several highway districts. The Clean Water Act permitting process is both lengthy and costly, taking two to three years or more and costing hundreds of thousands of dollars. Penalties for Clean Water Act violations can run up to $37,500 per day for each violation, and penalties are often stacked when an action is considered in violation of multiple permit provisions, such as, for example, an unpermitted discharge coupled with exceeding a pollutant limit.

As in the L.A. County example, Idaho MS4s may have permitted discharges that mix with other exempt or permitted discharge flows in man-made waterways, such as canals, irrigation or drainage ditches, or conduits, before reaching a natural waterway. Under the L.A. County decision, this mixing within a man-made waterway should not be a regulated discharge nor affect the permitted status of the mixing discharge streams.

This guidance then should benefit Idaho’s MS4 dischargers in documenting compliance with the Clean Water Act, as well as benefit those maintaining and operating man-made waterways including canals, drainage ditches, and channelized stream segments.

Murray Feldman is a Boise attorney and environmental law partner at Holland & Hart LLP. He can be reached at 208-342-5000 or mfeldman@hollandhart.com.

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