The Sierra Club Legal Defense Fund is scratching the bottom of the barrel for issues in its claim that Grand Canyon National Park is soft on polluters, the park superintendent says.

"This is just absolutely nothing," Jack Davis said of the fund's allegation Thursday that a hot-dog-and-lemonade stand eight miles west of the canyon village was dumping untreated sewage over the South Rim."The sewage is kitchen wastewater from the Fred Harvey Hermit's Rest concession," the fund said in a prepared statement issued through its Denver office.

Mark Hughes, a fund attorney in Denver, said in a telephone interview no refernce to human waste was intended.

"It's probably the stuff they use to wash the floor," he said.

Nevertheless, he said, such water commonly contains "fairly toxic solids."

He estimated that the concessionaire may have dumped 30,000 gallons over the past five years, and the group considers it enough of a problem that it mailed a letter of 60-day notice Wednesday that the stand is in violation of the federal Clean Water Act.

The fund will follow up with a lawsuit if action is not taken, Hughes said.

Davis said he and the state Department of Environmental Quality, which is responsible for enforcing the Clean Water Act in Arizona, became aware of the Fred Harvey outlet pipe over the rim four to five months ago.

He said the state agency was testing the water, estimated to amount to less than 20 gallons a day but had told him after preliminary analysis that it was "a minor matter."

"They can pursue it," he said of the fund, "but it is being dealt with appropriately. I don't know what legal cause they would have."

The concessionaire may be eligible for a waiver, Davis said. If not, he said, the stand will have to collect its dishwater and truck it away from the rim each day.

The water discharges directly into the ground in the Hermit Creek drainage, Davis said.

"They wash out their pots and pans at the end of the day," Davis said. "All the instruments with which people eat or drink are thrown away, so there are not a lot of dishes to clean."

He said the stand began operating in the 1920s, providing welcome hot chocolate in the winter and lemonade in the summer. Hot dogs are at the top end of the menu.

Davis criticized the fund's mention of sewage and reference to sinking automobile batteries in Lake Powell on the Colorado River upstream.

The Interior Department's inspector general issued a report last week which found that a concessionaire had disposed of batteries, paint and used boating equipment by throwing it into the lake.

"They don't like some of the things we were doing in relation to the concessionaires, and this is all part of that game," Davis said.

Hughes said there were few matters of small pollution.

"I think the American people think the national parks are some of the most precious places on Earth and think that they, like everywhere else, are being threatened by pollution," Hughes said. "I think when those parks are menaced by pollution, the public is very interested in it."

He suggested his organization was looking into other water-related problems but declined to discuss them.