Rep. Mike Thompson, D-St. Helena, introduced a measure in Congress Tuesday aimed at protecting thousands of acres of agriculture and open space.

The bill would offer tax deductions to landowners who choose to place conservation easements on their property. Property owners could deduct up to 100 percent of their adjusted growth income for 15 years.

Thompson’s bill has broad support from a grassroots coalition of farmers and conservationists. Conservation easements  historically have been used as a tool to protect farm land and open space, and Thompson said he expects this bill to enable more farmers to conserve their land.

“We’ve seen a 50 percent increase in conservation easements since Congress passed my provisions to enhance these tax benefits on a temporary basis in 2006,” Thompson said in a  statement. “If current development trends continue in California, another two million acres will be paved over by 2050. It’s time we made these protections permanent. By making sure that landowners can count on this program, we’ll take a big step forward in preserving our agricultural lands and open spaces.”

In August 2006, Congress passed provisions written by Thompson to strengthen tax incentives for property owners to donate conservation easements by allowing them to deduct a larger share of their income over a longer period of time. With these provisions, 535,000 additional acres were put into trusts in the last two years, according to the Land Trust Alliance, which is leading the national effort to make the easement incentive permanent.

“The Land Trust Alliance thanks Congressmen Thompson (and a co-sponsor, Rep. Eric Cantor, R-Va.) for their leadership on this incentive, which helped land trusts conserve 535,000 more acres in 2006 and 2007 than in the two years prior to its enactment,” Land Trust Alliance President Rand Wentworth said. “Their efforts to make this important conservation tool permanent in the 111th Congress are welcomed by America’s 1,700 land trusts and their two million supporters.”

The first land protected by Thompson’s provisions was local vintner Andy Beckstoffer’s Oakville vineyard. Beckstoffer Vineyards gave a conservation easement on

89 acres of the historic To Kalon vineyard in Oakville five days after the measure was signed into law.

John Hoffnagle, executive director of the Land Trust of Napa County, said he is “thrilled that Congressman Mike Thompson will lead the charge to champion conservation easement legislation again this year.”

“It’s a blessing to have a leader like Congressman Thompson representing our wildly diverse district,” Hoffnagle said. “He has seen firsthand the dramatic impact that the incentive has had in helping landowners permanently conserve farmlands and vineyards, wildlife habitat and open space in Napa and across the nation.”

Hoffnagle has worked with Thompson for years on various issues. His land trust has conserved more than 50,000 acres of land in the county.

The bill has 93 cosponsors. Thompson is a member of the House Ways and Means Committee, which has jurisdiction over all tax measures in Congress.