EPA Approves Chemical Control of Aquatic Weeds

Published June 1, 2005

Local governments and private individuals should not be required to obtain a special environmental permit prior to applying chemicals to control invasive aquatic weeds and other pests, ruled the U.S. Environmental Protection Agency in a January 25 interpretive statement.

The guidance, if adhered to by the courts, will eliminate confusion that ensued after a federal appellate court in 2001 ruled a local water agency violated federal law by failing to obtain a National Pollutant Discharge Elimination System (NPDES) permit prior to applying a chemical to an irrigation canal for the purpose of controlling invasive aquatic weeds.

Chemicals Control Weeds, Insects

Local governments have long used chemicals to control nuisance aquatic weeds and aquatic pests such as mosquito larvae. A small number of private individuals make similar aquatic chemical applications, but local governments, which care for most bodies of water, make the vast majority of chemical applications.

In May 1996, the Talent, Oregon Irrigation District applied a chemical herbicide to an irrigation and drainage canal to clear the canal of excessive aquatic weeds and vegetation. By not following the application directions on the herbicide’s EPA-approved label, the Irrigation District exposed local fish to excessive levels of the chemical, resulting in thousands of fish deaths.

In response, a pair of environmental activist groups sued the Irrigation District. According to the activist groups, the Clean Water Act required the district to obtain an NPDES permit for the chemical application, but the district had failed to obtain such a permit.

A federal district court ruled the Irrigation District was not required to obtain an NPDES permit. According to the district court, the application of aquatic pest control chemicals is adequately regulated by the Federal Insecticide Fungicide and Rodenticide Act (FIFRA). So long as chemicals that are addressed by FIFRA are properly applied, there is no need to obtain a NPDES permit, the court ruled.

The Ninth Circuit Court of Appeals, however, reversed the district court’s decision, saying the Clean Water Act requires an NPDES permit prior to applying “pollutants” into irrigation canals exchanging water with natural streams and lakes.

EPA Clarifies Proper Applications

In the wake of the Ninth Circuit decision, local governments were confused regarding their obligations under FIFRA and NPDES.

To settle the confusion, EPA issued its January 25 interpretive statement. According to that statement, the application of pesticides to waterways, if conducted in accordance with the directions found on an EPA-approved label, is consistent with all relevant requirements of FIFRA and therefore does not require a special permit under NPDES and the Clean Water Act.

Central to EPA’s interpretation is the fact that when a chemical is used in accordance with its approved purpose, its application does not “pollute” waterways. NPDES permits are necessary only for the discharge of pollutants.

Explained the interpretive statement, “Many of the pesticide applications covered by this memorandum are applied either to address public health concerns such as controlling mosquitos or to address natural resource needs such as controlling non-native species or plant matter growth that upsets a sustainable ecosystem or blocks the flow of water in irrigation systems.

“Under FIFRA, EPA is charged to consider the effects of pesticides on the environment by determining, among other things, whether a pesticide ‘will perform its intended function without unreasonable adverse effects on the environment,’ and whether ‘when used in accordance with widespread and commonly recognized practice [the pesticide] will not generally cause unreasonable adverse effects on the environment.'”

Reconciling its interpretation with the Ninth Circuit’s decision, EPA noted the Talent Irrigation District did indeed violate the application instructions found on the herbicide’s label. Under such circumstances, noted EPA, the Ninth Circuit was correct in finding the Irrigation District was required to obtain an NPDES permit.

James M. Taylor ([email protected]) is managing editor of Environment & Climate News.

For more information …

The U.S. Environmental Protection Agency’s January 25 interpretive statement is available online at http://www.epa.gov/npdes/pubs/pesticides_memo_interpretive_statement.pdf.