A host of pesticide and agricultural interests is lobbying for a farm bill amendment that would permit farmers and others to spray pesticides near U.S. waters without seeking a Clean Water Act permit first.

The Pesticide Policy Coalition, CropLife America, Syngenta Corp. and Dow AgroSciences are among the organizations listed as clients in new lobbyist registrations last month by John H. Thorne, according to Sunlight's lobbying registration tracker. Thorne recently joined the firm Bergeson & Campbell, which describes itself as an environmental law firm that helps "companies that make and use chemicals commercialize their products, maintain compliance, and achieve competitive advantage as they market their products throughout the world." The other organizations registered by Thorne are: Syngenta Corp, Bayer CropScience, SQM North America Corporation, and the National Agricultural Aviation Association.

Thorne, who represented some of these same entities at his old firm, Crowell & Moring, confirmed that the groups want Congress to approve an amendment proposed by Sens. Kay Hagan, D-N.C., and Mike Crapo, R-Idaho, designed to loosen regulations governing pesticides in water. The amendment would incorporate House-passed legislation, H.R. 872, to overturn a 2009 U.S. Court of Appeals decision that said that Clean Water Act permits are required for all pesticide applications that leave a residue in waters regulated under that law. The bill passed the House by a vote of 292 to 130, with 57 Democrats voting in favor, many of them from farm states. No Republicans voted against it.

"The court overturned an express EPA regulation reflecting the agency's more than 30 year policy that…[a Clean Water Act permit] was not required for…pesticide applications," says the letter. The letter emphasizes that these pesticides are already regulated under another law, the Federal Fungicide and Rodenticide Act (FIFRA), charging that the new regulatory scheme is duplicative.

Not so, say environmental groups, who have rallied in opposition. In an alert sent last weekend, the group Beyond Pesticides wrote that the legislation would allow pesticides in water "without any oversight, leaving you to swim, fish and boat on waters that are contaminated with endocrine disruptors, carcinogens, and neurological toxicants that are not monitored by federal or state officials."  Clean Water Action included the amendment in a list of "dirty water" amendments it's opposing in the farm bill.

A coalition of environmental groups wrote in a letter to senators sent last June that while pesticides are regulated under FIFRA, that law is primarily a vehicle for registration and labeling, and has not protected water and wildlife from harm.

Overall, the agricultural and chemical industries pack more campaign money and lobbying clout than do environmental organizations. In the 2012 cycle,  agribusiness has reported $39.2 million in federal campaign contributions; the chemical industry, $28.7 million, according to the Center for Responsive Politics. Meanwhile, environmental groups report $1.7 million in contributions.

With more than 250 proposed amenments to the farm bill, it's not clear yet whether the Hagan-Crapo amendment will get a vote, as the Senate continues to negotiate on how to structure the debate.