Thirteen acres of land surrounding a critical stretch of a Washington County trout stream will be shielded from development under a conservation agreement approved Tuesday.

The purchase by Washington County of what’s known as the Lauenstein property will protect a portion of Brown’s Creek near its headwaters in Grant, just west of Stillwater. The 4-0 vote by the Washington County Board is the latest action taken to counter impairments to the creek, a St. Croix River tributary.

“I appreciate any opportunity we get to enhance Brown’s Creek,” said Commissioner Gary Kriesel, who represents the Stillwater area.

The land, to be acquired for $254,400, sits just south of the Brown’s Creek headwaters and west of the Gateway State Trail. It was listed as one of the county’s top acquisition priorities under its voter-approved Land and Water Legacy program.

The undeveloped parcel includes a 1,300-foot stretch of Brown’s Creek and 2.4 acres of wetlands.

The county will pay half the cost with funds from the state’s Land and Water Legacy program. The other half will come from the Brown’s Creek Watershed District, which will reimburse the county in annual installments over five years.

The watershed district will own the property and develop a management plan for it.

In a Brown’s Creek land buy a year ago, Washington County and the city of Stillwater agreed to create public park space and protect a stretch of the creek and its wetlands on the southeast corner of Hwy. 96 and Manning Avenue.

The county bought that land, known as the Palmer property, for $200,000. The County Board spent $84,000 in Legacy funds to place a conservation easement on the property and sold it to Stillwater for the balance of the investment at $116,000.

Since Minnesota voters approved the Land and Water Legacy fund in 2006 to preserve open spaces and water quality, Washington County has used the fund to purchase more than 20 properties totaling more than 400 acres. That doesn’t include the largest potential land conservation project yet: up to 700 acres of woods and meadows north of Stillwater known as Wilder Forest.

A coalition of local governments, foundations and nonprofit organizations is negotiating a purchase of that land, which hosts rare and threatened birds and species such as turtles, snakes, hawks and bald eagles. It includes 12 miles of hiking and cross-country ski trails and 3.2 miles of easement for a future Gateway State Trail extension.