In response to this post, I got this email:
Okay, my average monthly domestic water bill is $50/mo or $600/yr for about 2/3 AF/yr. (I'm watering cows everyday on this water and go several months out of the year growing a 1/8 acre garden on drip).
My yearly irrigation water bill for 28 acres is about $700. I am allowed 3AF per acre/yr.
So say water prices get so high I get priced out of ag, the most likely event would be that this land would be turned into a subdivision, say 1/4 acre lots with 112 homes. If their average household use was 1/2 AF/year their water consumption would be a total of 56AF/year. So assuming my consumptive use is actually 2.5AF/yr that means I am using 70AF/yr to feed a lot of people. How do you like those numbers?
There are three questions here: water prices and food markets; land use (food vs. residential); and water use by land type
- If water prices rise across the board, food prices will also rise, but this rise will be dampened to the extent that competitors (with cheaper water) are able to supply the market. As I noted a few days ago, California has 40 percent of the Nation's vegetable acreage and 60 percent of its orchard acreage; that share will not fall too far with more expensive water. Agricultural markets can adjust to expensive water like they are (slowly) with expensive fuel.
- If markets allocate land, it's easy to see that farms can be converted into subdivisions, since the value of land with a house on it is often higher. OTOH, zoning, easements and lack of urban amenities can keep land in ag.
- How much water will be used on land that's farmed vs. subdivided? To know that answer, we have to know current ag use (IID land uses 6-8AF/acre-year) and consider the residential use. High density apartments will use a lot of water in total but not so much per person. Ranchettes may use a lot (lawns) or little (native vegetation). A 30 acre estate with "natural" groundcover may use less than all these options.
Bottom Line: Water use depends on many factors. Proper pricing of water (higher prices!) will minimize use -- no matter who the user is.
* Note that residential water costs $900/AF but agricultural water costs $10/AF. That's NOT because the quality of water is 90 times better but reflects the far higher fixed costs of residential water systems and probably reflects the cheaper costs of "sourcing" water for farmers who have senior rights.