A hard-fought battle over a proposal to designate thousands of acres of rural land south of Chatfield Reservoir for urban development roared to an end Monday, with landowners winning the first of several battles sure to come.

The Douglas County Planning Commission voted 7-2 to update the county's 2030 Master Comprehensive Plan, clearing the way for future residential and retail development in the rural, scenic Chatfield Valley basin.

"There will be a series of long drawn events before one shovel is turned," said Commissioner Marvin Taxar. "But we have an opportunity to do something special with this area."

The move could add more than 11,000 homes to fast-growing Douglas County, which has a population of 280,000.

The planning board's vote caps off three weeks of heated debate that drew a standing-room- only crowd Monday of 300 to 400 people.

Homeowners and developers have squared off over a proposal by 18 landowners to designate 5,150 acres of land suitable for urban development.

Opponents argued Monday that clearing the way for high density development puts at risk the natural environment of Chatfield Valley and the rural lifestyle many now enjoy.

"I see people jumping in and creating a situation that is not good," said Commissioner Steve Wilson. "If there is part of the county that shouldn't be developed, this is one of them.

Taxar argued that the new urban designation won't necessarily lead to high-density development. The master plan puts a number of restraints on developers, including a requirement that they preserve open space and a sustainable source of water.

A majority of the land is owned by Sterling Ranch LLC.

Taxar and others contend the change to the master plan makes it possible to bring needed infrastructure to the area, including roads, schools and water to neighboring subdivisions where wells are in danger of running dry.

"There is no way we will increase water, road and schools and other needed services without a cost," said Roger Partridge, chairman of the planning board.

Harold Smethills, managing director of Sterling Ranch, estimates that it could cost $220 million to construct a water-treatment facility to serve the Chatfield Valley.

Commissioner Charlotte Mirabella, who voted against the plan, contends the proposed development comes at too high a cost.

"We're putting at risk a large area that is going to change drastically from what it is today," she said. "We'll lose the opportunity to preserve a lot of natural land here."