SALEM (AP) — U.S. Sen. Gordon Smith’s frozen foods processing company faces a potential state fine for discharging wastewater from its Eastern Oregon plant into a nearby creek, the most recent of several spills at the plant.

The state Department of Environmental Quality said Tuesday that Smith Frozen Foods Inc. contacted the agency last month to report that corn processing water from the company’s plant at Weston had flowed into Pine Creek.

Joanie Stevens-Schwenger, spokeswoman for the state agency, said the incident was still under investigation and that no fine has been proposed yet against the company owned by Smith, who’s facing a tough re-election campaign this fall.

Asked to characterize the seriousness of the wastewater discharge, Stevens-Schwenger called it a relatively minor environmental mishap.

“The company took immediate remedial action” to fix the spill, she said. “There was no ecological damage. We didn’t have a fish kill.”

Smith’s company has been fined for past spills.

In the most serious one, in 1991, wastewater flowed into the creek for 15 days, killing fish and drawing a $100,000 fine from the state.

That spill became a campaign issue when Smith made his first run the Senate in 1995. Democratic opponent Ron Wyden, who defeated Smith in that race, ran advertising that attacked him as a “chronic corporate polluter.”

A year ago, Smith Frozen Foods paid a $3,000 fine for a smaller spill similar to the one that occurred in July.

Smith’s Democratic challenger, Oregon House Speaker Jeff Merkley, took aim Tuesday at the latest spill.

“It reflects a larger pattern, which is his company’s record of polluting Oregon’s waterways and his votes in Washington to roll back environmental regulation,” Merkley spokesman Matt Canter said.

The Republican senator owns Smith Frozen Foods along with his wife Sharon, although they turned over day-to-day operations to others after Smith was elected to the Senate in 1996.

Tom Lindley, the company’s lawyer, defended its environmental record. He also said last month’s spill involved five to 20 gallons of a mixture of water and corn residue that leaked through soil at the plant, into an old storm drain and then into Pine Creek.

A worker discovered the spill less than 24 hours after it began, and the company immediately began efforts to stop the spill and put three pumps into the stream to collect what was left of the milky-looking corn processing water, he said.

Lindley dismissed the Merkley campaign’s criticism as election-year rhetoric.

“This is one of the most closely watched companies in the Pacific Northwest, because it is owned by a U.S. senator,” he said. “We know that in every election campaign, someone is going to try to make something out of any event, no matter how small.”