Three more tracts of land are under review in Washington County for possible open space preservation.

One of them is a strip of 16 acres along the St. Croix River just north of downtown Stillwater, adjacent to the new Browns Creek State Trail corridor. The owner, Elayne Aiple, has told the county that she prefers to see her land preserved through public ownership.

Farther south, in Denmark Township, rural properties of 143 acres and 75 acres will be considered as well.

"All three projects represent either the county's priority areas or a priority within a local community," said Jane Harper, the senior planner who coordinates the Land and Water Legacy Program.

The county will arrange appraisals of land values on all three proposals, Harper said. No decisions have been made on whether to buy the land, and negotiations typically take months and sometimes years.

The most recent purchases came in August and September, when the County Board voted in favor of buying two tracts of land at Big Marine Lake to preserve as green space. The acquisitions were the eighth and ninth major transactions under the umbrella of Land and Water Legacy, a voter-approved county initiative to protect natural areas against development. The county thus far has spent $3.7 million to preserve 236 total acres, Harper said.

Here's the most recent lineup of candidates:

• The Aiple Property in Stillwater. This strip of land, flanking the new Browns Creek State Trail, includes 4,000 feet of St. Croix River shoreline. Four undeveloped acres outside the gate of a personal residence remain in a natural state. The developed portion of the property includes a house, a long driveway, a man-made trout pond and large docks.

Despite the property's prime location and riverfront appeal just north of downtown Stillwater, various government agencies haven't reached agreement on how it could be managed, Harper said.

The National Park Service cannot acquire the property because it's just south of the St. Croix National Scenic Riverway boundary. The City of Stillwater hasn't taken a position on a possible purchase, Harper said, and the Metropolitan Council has said the land is too small to qualify as a regional park.

Another prospective owner, the Minnesota Department of Natural Resources, has reservations as well, Harper said. "They were concerned about this property because it has considerable shoreline modification and it does have a house on it," she said.

• The Shirley Keegan Conservation Easement in Denmark Township. This property, situated between St. Croix Bluffs Regional Park and the Lost Valley Prairie and Scientific Area, would create a "critical habitat corridor" along the St. Croix River near the south end of Washington County.

"In itself it's a lovely piece of property," County Commissioner Gary Kriesel said. The current proposal would allow farming to continue if the county bought a conservation easement on the property to protect it from further development.

Some members of the County Board questioned the purpose of investing in the land unless public access was assured.

"Agriculture is very important to the area," Kriesel said. "I certainly don't want to be punitive to people who are growing crops."

The estimated market value is $1.2 million.

The property includes rare Bedrock Bluff Prairie. It also has ravines with wooded slopes critical to controlling runoff and maintaining the water quality of the St. Croix River, Harper said.

• The Carpenter Nature Center Conservation Easement in Denmark Township. This tract of orchard, wooded bluff land, restored oak savannah and restored prairie also has 3,000 feet of St. Croix River shoreline. The property includes abandoned railroad right of way along the river that someday could become part of the planned St. Croix Valley Regional Trail.

The estimated market value is $1.4 million.

Purchase of the land would save it from development and maintain a natural buffer along the river to avoid further runoff contamination, Harper said.

Washington County voters approved the Land and Water Legacy effort in 2006. The referendum allows the county to spend up to $20 million to protect drinking water resources, purchase parkland, preserve wetlands and woodlands, and protect land along water bodies from development.

Kevin Giles • 651-925-5037 Twitter: @stribgiles