SALEM — A proposal to allow Oregon farmers to clean more sediment from ditches without a permit has encountered opposition from environmentalists who warn of unintended consequences.

Under House Bill 2437, farmers could dig out up to 3,000 cubic yards of dirt per mile of drainage ditch in wetland areas over five years without a state fill-removal permit, up from the current limit of 50 cubic yards per year.

The work could be conducted only when the channels are dry unless the landowner obtains a variance from the Oregon Department of Agriculture, which would oversee the program.

Farmers argue that removing 50 cubic yards per year isn’t enough to prevent ditches from clogging, interfering with field drainage while filling channels inhabited by fish with dirt.

“Both farmers and fish suffer if people can’t get in to do this work as often as it’s needed,” said Mary Anne Cooper, vice president of public policy for the Oregon Farm Bureau, during a Jan. 31 legislative hearing.

Several environmental groups urged the House Committee on Agriculture and Land Use against recommending the bill for approval, claiming that allowing an “exponential” increase in the amount of dirt removed from ditches could adversely affect fish.

Ditches can serve as important winter habitat for salmon and steelhead as well as a “nursery” for juvenile fish but HB 2437 would let farmers dredge these channels with scant oversight from wildlife regulators, said Brian McLachlan, a volunteer with the Association of Northwest Steelheaders.

“These habitats are part of what used to be a vast off-channel floodplain complex,” he said.

While the bill would require Oregon State University to complete a study of dredging effects over five years, that may encourage farmers to remove as much sediment from ditches as possible before the report is complete, McLachlan said.

“We think that’s putting the cart before the horse,” he said.

The Nature Conservancy would prefer if the bill recognized that ditches in certain geographies and landscapes may need to be treated differently, such as coastal streams occupied by coho salmon. Other streams can be cleared aggressively without detriment to fish, said Jena Carter, the group’s Oregon coast and marine director.

The organization recommends that “essential salmonid habitat” be excluded from the increased removal limit and requiring a “waiting period” during which the state government can review planned ditch-cleaning activities, she said.

Trout Unlimited believes the volume cap under HB 2437 should be reduced to 300 cubic yards per linear mile, which could be modified once the study of the law’s impacts was finished, said Chandra Ferrari, senior policy advisor with the group.

Under current rules, only about 20 farmers have actually sought fill-removal permits to dig out more than 50 cubic yards of dirt from ditches, which indicates growers are not using the permit process and the state isn’t enforcing the rules, said Rep. Susan McLain, D-Hillsboro, who led a work group that developed the proposal.

The bill is intended to implement a system that’s actually used by farmers and can be enforced by the state government, she said.

Until now, the Department of State Lands — which oversees fill-removal permits — has provided inconsistent and sporadic enforcement based on complaints, since the agency doesn’t have the resources to monitor every ditch being cleaned in the state, said Dave Hunnicutt, president of the Oregonians in Action property rights group.

“A rule that is universally ignored doesn’t really do any good,” Hunnicutt said.

Since flood-control measures prevent waters from rapidly rising and falling on the Willamette River, systems have filled with sediment and new fish habitat isn’t being created, said Peter Kenagy, a Benton County farmer whose property abuts a river.

The state government needs to provide landowners with an efficient way to maintain channels so they remain clear for fish to travel to colder waters in spring, Kenagy said. “One of the biggest threats is the fish can’t get out.”