We have four major rivers flowing out of our state: The Platte, Arkansas, Colorado, and Rio Grande. All of them have “compacts”, which are multistate agreements, as to the flow which must be in the river at the state line. Colorado has a tendency to overdraw water until someone files a lawsuit. Then the state shuts down wells in response. That gets messy for the farmers who lose their wells after all the irrigation investment.

This valley is just over the Sangres from us but to get in the Valley, we have to go up to Salida then turn south or go down to Walsenburg and turn west.

Here are the Sangres on our side.

This is in April of 2007.

This is the western side of the Sangres.

This was taken in the Fall of 2008 but normally less snow falls on this side of the mountains than the eastern side. The pastures are filled with Rabbit Brush and Sage Brush.

This Valley only gets about 8″ of rain making it a true desert. And the base of the valley is largely sand and gravel washed down from the surrounding mountains. Deep gravel. If the valley were emptied of gravel, the resulting canyon would be 9000′ deep with the bottom in places, near sea level. The north end of the valley is hydraulically independent of the lower part due to the geology. The whole San Luis Valley is a consequence of the Rio Grande Rift.

As you can see on the larger map, there is much center pivot irrigation in the Valley. Which is the problem.

Water worries in Colorado’s San Luis Valley come to surface, an article in the Denver Post.

SAN PABLO — Water here is so scarce that farmers habitually gaze up at the mountains surrounding their valley — where overpumping from aquifers may force 80,000 irrigated acres out of production.

As Rose Medina traversed her ancestral lands last week, scanning the Sangre de Cristos for the promise of a strong spring runoff, she saw barely a dusting of snow.

“Looks like we’ll need more,” Medina said.

Big spring snow could send water coursing down Culebra Creek and into her “lindero” boundaries — headgates controlled by an elected “mayordomo” steward — allowing growth of hay for her 16 cows and quenching her apple, plum and cherry trees. The ancient Moorish water-sharing methods adapted 400 years ago in southern Colorado ensure that, even in dry years, small family farmers survive.

But survival is far from ensured across the broader San Luis Valley, where leaders in an area that’s already among the poorest in the state are bracing for a major economic hit.

“Agriculture alone cannot sustain the economy of the San Luis Valley,” Colorado agriculture commissioner John Salazar recently told residents.

Unlike Medina’s 40-acre farm and others that rely on only surface water, the commercial agriculture that built up the valley is large-scale and competitive, and relies on center-pivot irrigation devices that pump heavily from underground aquifers. Commercial production of potatoes and hay — using 6,000 wells and 2,700 center-pivots to irrigate 120-acre crop circles — exploded after the 1950s.

The pumping has depleted aquifers by more than 1 million acre-feet since 1976 and now is affecting surface streams. One acre-foot approximately serves the needs of two families of four for a year.

By May, center-pivot farmers must activate a plan to reduce the water pulled from the aquifer by about 30,000 acre-feet a year.

“They’ve got to start to restore it,” state engineer Dick Wolfe said.

To avoid state shutdowns of wells — as happened in 2009 in northeastern Colorado — commercial farmers propose to pay to pump or purchase new surface-water rights and use these to offset pumping from aquifers.

But the time has come for commercial farms “to pay for the impacts they are causing to the river,” said Steve Vandiver, manager of the Rio Grande Water Conservation District and the leader of efforts to find water to replace water pumped from wells.

Rio Grande County Commissioner Karla Shriver, who in the 1990s led opposition to a Canadian developer’s push to plumb the valley’s deep aquifers and export water to booming Front Range suburbs, said mining jobs must make a comeback to help cushion the loss of irrigated acres.

Meanwhile, small-scale farmers like Medina, who hold long-established rights to surface water, are relatively unaffected and already have other sources of income. She works as a teaching assistant.

She counts only on snowpack to keep creek water flowing into gravity-based “acequia” ditches.

The communal People’s Ditch system in San Pablo, San Luis and neighboring Spanish land-grant communities, which dates to 1852, increasingly serves as a model of prudent agriculture. Interior Secretary Ken Salazar calls it “a perfect example of an important part of history that needs to be preserved.”

We have a saying in Colorado, “Whiskey is for drinkin’; water is for fightin'”. So on we go.