It's a remarkable coincidence that Amador County's rights to 15,000 acre feet of water from the Mokelumne River almost exactly match the number of acre feet needed to provide water to everyone on the Amador Water Agency's list of proposed projects in its service area.

In the controversial water supply assessments for the proposed Wicklow Way subdivision and Gold Rush Ranch and Golf Resort, complex calculations conveniently add up to an annual usage rate of 14,972 acre feet of water by 2030. That leaves only 28 acre feet. It is this figure that has led the water agency to warn everyone that the county is going to "run out of water" in 2030, just over 20 years from now.

Almost mystically, the national and worldwide economic downturn has provided this little county with a bit of breathing room, a chance to sort out the development projects that would use up all the water. The agency put in a large pipeline in 2007 and will begin digging the trench for the Plymouth pipeline very soon. By agency calculations, eliminating leakage and evaporation from the old Amador Canal makes the entire 15,000 acre feet of water available.

The water supply assessments make a rather simple set of equations into a tangled mess, as they use various terms to, well, muddy the water. They have countless unnecessarily strange-sounding words that begin to arouse suspicion that there's something to hide. What we really need to know is how many more houses can be built on the water that the county has available.

The answer to this question is elusive. All we know for sure is that it's a finite number, which might be a very good thing, since that means there is an upper limit to the number of houses in Amador County's future.

In the WSA, the agency states that existing demands use 42 percent of available water. In the county's most recent general plan housing element, there is an estimated population of just over 15,000 people in urban areas. If these people are using 42 percent of the water, then the other 58 percent should provide water for approximately 21,000 more people. Recycling and water conservation may raise that number somewhat. AWA General Manager Jim Abercrombie hopes to use the agency's "purple pipe" plan to replace up to 20 percent with potable water that would otherwise go to industrial, parkland or golf course uses. If the agency reaches that goal, it could have enough additional water for another 9,000 people.

So, adding all of these numbers together, the total population supportable by the agency's 15,000 acre feet of water equals 45,000. Now, here's a formula to work with: three people per acre foot.

Of course, there are other sources of water in the county. The upcountry Central Amador Water Project, operated by the AWA, has rights to 1,150 acre feet right now. If AWA's plans to raise the dam at Lower Bear Reservoir can be carried out, another 3,850 acre feet of water rights may be solidified. Using the formula, the 5,000 acre feet can support another 15,000 residents, which raises the total population to 60,000.

Well water is the only source for most of the county's residents in unincorporated areas. The county planners are wisely leaning toward discouraging development projects that have no access to secure water sources. There seems to be wide agreement that an average household in the county is around 2.5 persons. This leads to an estimate of 14,400 existing houses for Amador's 36,000 residents. For the additional 64,000, the county would need approximately 25,000 more houses. Estimates of pasture, rangeland and farms in Amador County hover around 200,000 acres. If smart growth were totally ignored and the 25,000 houses sprawled about the countryside on 1-acre lots, they would use approximately 12.5 percent of the land area. If smart growth principles are not ignored, those houses will cover far less land. If 10 percent or 20 percent have to be affordable housing, they'll be even more concentrated.

Of paramount importance is the realization that, barring some miraculous discovery of hidden water rights, there is only enough water for no more than 25,000 new houses. What springs from this is recognition of both a power and a responsibility to pick and choose among proposed projects, making sure that what gets built represents the best and highest use of Amador County land.