BOULDER — A proposal that Boulder County pay $6.7 million to buy 190 acres of irrigated farmland straddling East County Line Road southeast of Longmont got the support of Boulder County’s Parks and Open Space Advisory Committee on Thursday night.

That land, which the county staff has designated the Ross Property, lies within an existing region of county-owned open-space parcels and private properties covered by conservation easements between Oxford and Pike roads. Committee members voted unanimously to recommend that the Board of County Commissioners proceed with the purchase.

The Ross Property includes 80 acres in Boulder County, which the county would retain as open space and probably lease out for continued agricultural use, as well as 110 acres in Weld County that the county intends to eventually sell. The purchase price includes the value of water rights and a small house, a small barn and several sheds on the Boulder County side of East County Line Road, and a small barn on the Weld side.

Mel Stonebraker of the Parks and Open Space Department said the 80 acres that lies within Boulder County “is the last piece in a beautiful mosaic of protected open space that covers nearly 5,000 acres” in that area.

“The Ross Property and much of the surrounding open space is arguably the best agricultural land in Boulder County,” Stonebraker told county committee members. “The preservation of the Ross Property has always been a high priority, and the county has tried for years to purchase it.”

County purchase of the property would help extend a buffer of undeveloped land along the Boulder-Weld county line, Stonebraker said, even after the Weld County portion is sold to a new private owner. When Boulder County finds a buyer “willing to pay a reasonable price” for the Weld acreage, Boulder County would retain a conservation easement that would restrict or prohibit that buyer’s ability to put new buildings on the Weld portion.

Boulder County expects to offset some of the $6.7 million overall price tag of the acquisition with the sale of that 110 acres in Weld County, as well as the sale of all or a a portion of the Northern Water Conservancy District Big Thompson shares that Boulder County is getting as some of the water and ditch rights that will come with the total 190-acre purchase. The county would keep some of the less expensive water rights it’s getting in the transaction.

Also, the county could eventually make an estimated $400,000 by sell off some of the rights that a private owner might otherwise have to develop the 80 acres of the Ross Property that lie within in Boulder County, transferring those rights to a buyer who wants to build in another part of the county. And Boulder County has a grant from the federal Farm and Ranchland Protection Program to help pay for the value of the conservation easement it would retain after selling the Weld portion of the Ross Property to a new owner.

Meanwhile, the current owners of the Ross Property, which Stonebraker said is “a complicated ownership” that includes a number of related individuals, would retain ownership of the property’s mineral rights and continue to collect royalties on a number of oil and gas wells that are there now.

Boulder County would pay for the portion of property located in this county, including water rights, with $2.8 million open-space sales-tax funds.