OLYMPIA — An adviser to Gov. Jay Inslee was the only one to testify Tuesday against a bipartisan riparian buffer bill that is supported by farmers and tribal leaders.

Introduced by two Democrats and two Republicans, House Bill 1720 contrasts sharply with legislation Inslee proposed last year that called for wide and mandatory buffers on farmland.

HB 1720 relies on a “fully voluntary” program run by the state Conservation Commission.

Farmers could get grants for seeds, trees, fences, manual weed control and for other expenses related to planting and maintaining strips of vegetation along waterways.

The bill does not call for buffers as wide as the tallest trees growing on riverbanks. Instead, conservation districts and farmers would work together to tailor buffers for specific sites.

Inslee senior policy adviser Ruth Musgrave told the House Agriculture and Natural Resources Committee the lack of a statewide minimum standard for buffers is a flaw in the legislation.

Inslee’s bill last year pushed for buffers 200 feet or wider. “Without a minimum standard, the investment may not meet its intended goal,” Musgrave said.

Committee chairman Rep. Mike Chapman, D-Port Angeles, said after the hearing that lawmakers will need to talk to Inslee. “He has the veto pen,” said Chapman, HB 1720’s prime sponsor.

Still, buffers should be flexible, and imposing uniform buffer widths would be out of step with what he and his co-sponsors are proposing, Chapman said.

“Statewide minimum standards quickly become regulatory. It quickly becomes contentious,” he said.

Inslee came back with another buffer bill this year, but it has again failed to move. Although it called for funding voluntary buffers, it also would have set up a task force to look at new regulations.

Inslee proposed spending $100 million to support his buffer bill. Chapman said he supported diverting the $100 million to carry out HB 1720.

Tribes say riparian buffers are needed to protect fish. Some tribes stayed neutral on Chapman’s bill Tuesday, but none outright opposed it and several indicated support.

Jamestown S’Klallam Tribe Chairman Ron Allen said tribes and farmers need to work together. He praised Washington Farm Bureau President Rosella Mosby for her role in developing the bill.

“I know some, even including the governor, would like to see more rigid requirements and mandates,” he said. “I think that with the spirit of Rosella and others, we can make this work.”

Stillaguamish Tribe of Indians Councilwoman Kadi Bizyayeva said the bill had good intentions, but the tribe wasn’t ready to endorse it.

“There is some concern the current language may not be strong enough to prevent further habitat degradation or complacency,” she said.

Several farmers testified via video in support of the bill. “This voluntary approach will gain much more traction in the farming community,” Whatcom County dairy farmer Jeff De Jong said.

To close the hearing, Chapman noted that 218 signed in to a legislative website to support the bill and four signed in to oppose it. He said he will insist the bipartisan spirit continue.

“This will be a bipartisan bill or it won’t move out of committee,” he said.

The top-ranking Republican on the committee, Rep. Tom Dent, R-Moses Lake, one of the bill’s four original sponsors, was as enthusiastic after the hearing.

“This is historic legislation,” he said.

Reps. Debra Lekanoff, D-Skagit County, and Joel Kretz, R-Okanogan County, were the other two original sponsors. After the bill was introduced, 21 other House members, across the political spectrum, signed their names to the bill.