With a history dating back over 2,000 years, the windmill represents one of man’s most enduring mechanical contrivances. There are few images more representative of the arid American west. It’s a clean-energy, labor-saving device older than the terms that describe it.
Given 15-to-20 mile an hour winds, an 8-foot diameter windmill can pump around 150 gallons an hour. An average family of four might use 200 to 300 gallons of water a day, so 150 gallons an hour is, by at least one measure, a lot of water.
While it’s not uncommon to see windmills next to houses, they’re also often the only landmarks in the long stretches of desolate rangeland that typify much of the American west. Oftentimes, the presence of a windmill indicates the presence of cattle, whose thirsts are quenched with groundwater pumped by the trusty wind machines.
There was a time when windmills were common along the dry edges of the San Joaquin Valley. Cattle ranchers and cowboys headed for the hills after they were crowded off the Valley floor.
Today, even in the foothills, windmills and cattle ranchers are going the way of hitching posts and rawhide lariats. Once, disappearing windmills might have been attributed to housing tracts and strip malls. Today, almond orchards are a bigger factor in lost rangeland than developers .
According to a recent study, the San Joaquin Valley lost the most rangeland in the entire state in the last two decades, and 54% of the conversion was to agricultural uses. Once brown and sere, the foothills have turned green and moist.
The source of the moisture is an underground storage system of almost incalculable value—some of the last untapped groundwater in the state. Fed by aquifers filled with water thousands of years old, foothills groundwater is proving a bonanza for investors with enough front money to afford the acreage, trees, and industrial-sized pumps necessary to turn dry rangeland into verdant orchards.
Compared to the stately windmills, the new pumps are unimposing things, squat and hardly noticeable. Because of their remote locations, most run on diesel fuel; electricity isn’t available.
The unimposing nature of the pumps, the invisibility of groundwater, and the hidden delivery system of drip irrigation keep groundwater out of sight and out of mind. That’s one reason it’s so susceptible to overuse. Entire lakes and reservoirs of the stuff can be pumped onto large orchard tracts and almost no one sees the water.
Consider it this way: At full capacity, Modesto Reservoir, which stores drinking water for the city of Modesto, holds 29,000 acre feet of water. That’s barely enough water for 10,000 acres of almonds for one year. But 10,000 acres of almonds is a mere fraction of the acreage that’s been added to Valley foothills in recent years. The new almond inventory needs hundreds of thousands of acre feet of water year after year after year.
And that’s why the new pumps, squat and unimposing as they are, are capable of spreading 2500 gallons a minute over the land around them. Figure there are hundreds of these pumps in Stanislaus County alone, and you begin to get some sense of just how much water is being taken from the ground.
Experts agree it’s water that won’t be replaced any time soon. It took thousands of years to create the foothills aquifers, but modern technology will drain them in couple of decades. For some, that’s progress. Others might think we were wiser using windmills for cattle and rangeland.