In some places, politics is dirty.

In Napa County, politics is dirt.

Dirt and vines and water rights and construction sites. While local citizens are engaged (and some enraged) about the war in Iraq, the consequences of immigration and global climate change, the substance of politics here is what happens on the ground.

That's true whether we're talking about leveling dirt for 12 homes on Linda Vista Avenue in Napa, shaping dirt into terraces to contain the flows of the Napa River or adding hundreds of new homes on Pacific Union College property in Angwin.

One reason dirt is so interesting to so many is money, of course, because there's lots of that to be made if real estate is put to its highest economic use. But the importance of dirt also has to do with residents' changing perceptions of a community.

When a new development is proposed in the city of Napa, be it major or minor, it spurs reflections on the old days. For example, within living memory the Ghisletta Ranch was south of Napa and stretched from the western hills to the Napa River. Today, Highway 29 cuts through it and a big chunk of the ranch has been acquired by the government for flood control. In the coming years, the remaining open acreage will likely become a new residential neighborhood.

That's a big deal. Right now, though, it seems the biggest deal is taking place in rural Napa County, in a place that a relatively small percentage of us know well -- Angwin. The situation in Angwin is fascinating, containing elements not common in the other debates about development pressures.

Angwin has traditionally been an enclave for Seventh-day Adventists who, by and large, share a similar set of values about community and social priorities. That is less so today than it has been in the 100 or so years since Pacific Union College was established, in part because people of varying backgrounds have moved in over the decades to embrace the country life, and in part because Howell Mountain is now highly regarded vineyard land.

Angwin's pulse is the well-regarded PUC, with more than 1,000 students and a few hundred workers and faculty members. Like any college town, Angwin is home to graduates and teachers and others who have a deep loyalty to the school. They want to see it succeed as far into the future as anyone can reasonably forecast.

So when the school proposes expanding its endowment by building homes that might add 1,500 or 2,000 residents and supporting businesses whose practices may or may not be consistent with traditional Adventist values, the issues to contemplate are far deeper than what would show up on a zoning overlay map or graph of the local water table.

Even PUC's "eco-village" concept, incorporating environmentally-friendly building and living concepts, has to be seen through a different prism than it would in, say, Napa city.

At the Register these days, we are regularly covering half a dozen proposals for dramatic change in Napa Valley, including several in town. But the bigger changes may be coming out in the country.