The proposed development at the former Napa Pipe site is looking more attractive to county officials as it becomes clear that pressure from the state to build affordable housing isn’t going to let up any time soon.

On Tuesday, the Napa County Board of Supervisors unanimously approved a long-term housing strategy that acknowledges the mixed-use Napa Pipe proposal as a reasonable solution to the county’s housing dilemma.

The county’s housing plan features 10 strategies, including a promise to continue lobbying for changes to the state law that imposes new housing requirements every seven years on counties and cities. Meeting affordable housing mandates has long been Napa County’s Achilles’ heel.

But the board-approved plan mentions only one development by name: Napa Pipe.

Supervisor Mark Luce said the state housing mandate is in “direct conflict with our General Plan goals of protecting agriculture and open space, but it’s, nonetheless, state law. … Another couple thousand units has to be zoned somewhere in the next 20 years, and that’s where Napa Pipe just stands out as a wonderful solution to that problem.”

The mixed-use development proposed at the south-county Napa Pipe site features 2,580 townhomes phased in over about 20 years.

“If we could actually have an agreement with the (state) that the county would satisfy its next three housing (allotments) through project approval here, “ Luce said, “then we basically have avoided the need to zone any land for residential use outside of city limits, apart from Napa Pipe.”

The housing plan approved on Tuesday allows for four possible scenarios regarding Napa Pipe..

First, the county will negotiate a development agreement with Napa Pipe developers to phase in residential development over the next 20 to 25 years. Twenty percent of the homes must be affordable.

The county will also negotiate a three-party agreement with Napa Pipe developers and the state. Under this option, the county would get credit toward future housing requirements for participating in a pilot program to monitor workforce housing and greenhouse gas emissions at Napa Pipe.

The county will also see if a deal can be struck with the city of Napa in which the city would take on the county’s housing requirements. In return, the county would agree to support placing the Napa Pipe site in the city’s sphere of influence — a key step toward annexing the site into the city.

Similar talks between the city and county failed last year, but Napa Mayor Jill Techel said she looks forward to resuming negotiations with the county.

“I am pleased that we’re part of the strategies that they’re looking at and I think it’s probably time for us to start these conversations up again,” Techel said.

The fourth scenario approved by the board Tuesday includes considering the Napa Pipe project without any sort of development agreement.

Napa Pipe developer Keith Rogal said he is pleased with the outcome of Tuesday’s vote.

“A long-term housing strategy that includes Napa Pipe — the largest, centrally-located, already-paved piece of property ever to become available in the county — is a wise public policy choice for the county,” Rogal said.

Supervisors said that while the county included Napa Pipe in its overall housing strategy, the move does not necessarily signal approval of the project, which is expected to come up for public hearings and a vote in the next several months.

“It’s an indication that we’re trying to get our housing numbers solved in whatever way we possibly can,” said Supervisor Brad Wagenknecht. “I don’t think there’s a real change in direction in this.”

Supervisor Keith Caldwell agreed. “I think that we sent a clear message that (Napa Pipe) is certainly one of the options that the Board of Supervisors has available to meet its overall program needs. … (but) I think that there are other options within those 10 that are just as important as the Napa Pipe option.”

Other strategies approved Tuesday include working with private property owners such as nonprofits to add housing stock, and looking for ways to locate new homes in the cities rather than unincorporated areas of Napa County.

The county has also agreed to consider the use of surplus county-owned land for affordable housing. A study into whether and where this is possible should be out by the end of 2011.