Opening Day was spoiled for several fishers at the Denman Wildlife Area after a popular spot mysteriously drained within hours, leaving investigators wondering if vandalism or a breached dam was at fault.

Opening Day was spoiled for several fishers at the Denman Wildlife Area after a popular spot mysteriously drained within hours, leaving investigators wondering if vandalism or a breached dam was at fault.

Doug Evans knew something was amiss Saturday afternoon as he watched the irrigation pond's level drop noticeably by the hour. He arrived with his family at around noon. By 4 p.m., the pond, which measures between three and four acres, was reduced to a mudhole writhing with dying carp, blue gill and catfish.

"I've been fishing here since I was 15 years old," Evans said as he watched a large carp flop in the mire. "This is terrible."

The pond sits just off East Gregory Road near Whetstone Pond. It is used to irrigate the wilderness area, said Denman Wildlife Area assistant manager Dan Eldridge.

The water, along with hundreds of fish, was disappearing through a broken dam at the northwest side of the pond used to keep the fish hole from draining into a nearby creek.

It appeared that the wood had either become so rotten that it could no longer hold back water, or someone had intentionally broken the boards sealing the culvert.

"Our first impulse is vandalism," said Oregon Department of Fish and Wildlife fish biologist Dan VanDyke. "It could be equipment failure, but if someone was seen removing boards from the site we would like to know about it."

VanDyke walked the perimeter of the pond collecting fish and mud samples to aid in the investigation.

Eldridge and VanDyke pulled on their hip waders to fight through the mud as they repaired the dam with newly cut boards. By 5 p.m. the water was stopped, but the damage was already done.

"This pond is important because it services our ditches around here," Eldridge said. "It should fill back up in a few days from the ditches above it."

Eldridge primary concern was the water holes downstream, which rely on fresh water draining in from the affected pond. Those ponds could see fish deaths if the water does not receive enough dissolved oxygen.

It seemed that many of the fish that were funneled into the culvert managed to survive the trip downstream, VanDyke said.

"I saw some of the larger fish swimming downstream," he added. "The silver lining we have here is many of the warm-water species have high reproductive rates and can come back quickly."

For Evans the sight of fish and Canada geese floundering in the mud was enough to make this Opening Day one to forget.

"It looks like we are the last ones to catch a fish out of here for a while," he said.

Anyone who saw suspicious activity at the pond late Friday or early Saturday is asked to call Oregon State Police dispatch at 776-6111.

Reach reporter Chris Conrad at 776-4471; or e-mail cconrad@mailtribune.com.