From the Twin Falls Times News:

Recognizing early on the effects that groundwater pumping can have on senior surface-water rights, Colorado officials tried a proactive solution, said Dick Wolfe, state engineer and head of the Division of Water Resources since 2007. Junior well users since the early 1970s have generally had to file court-approved “augmentation plans” before they can operate, describing how they will replace the water they use in times of shortage. The system worked — until a severe drought in 2002 pushed it to its limits. The ’80s and ’90s had been among the wettest on record for the South Platte Basin in northeast Colorado, the state’s largest basin in terms of water use. Then the drought hit, Wolfe said, and augmentation plans developed for shortfalls decades before were insufficient to handle the sheer level of need. Stream flow only reached 25 percent of usual. Groundwater pumpers scoured the market for water supplies, competing with cities and other water users who were also reluctant to part with their extra water. Prices skyrocketed: What once cost only $10 to $50 per acre-foot commanded sums as high as $700 per acre-foot, Wolfe recalled. Tension and conflicts rose with the increased competition for costly, limited supplies…

The agency faced the daunting task of examining about 8,200 physical, high-capacity irrigation wells, some of which would have to be completely shut down. Employees started with the wells along the main stem of the South Platte River, creating an inventory of several thousand in the curtailment’s first year and notifying the owners of wells that had to be shut off as they went. Only 5,800 wells were legally able to operate after the first couple years of work. Many of those were still “severely” restricted due to the drought, Wolfe said. Half of the remaining 2,400 wells were records errors and didn’t exist any more. At least 500 to 1,000 belonged to people who had no augmentation plan in place…

The inventories and inspections are still going on seven years later. And though water issues continue to be fought out in court, the basic process Wolfe follows has been upheld by the state Supreme Court. Given the task his agency faced, he feels it’s been handled well — even quickly. And the work has only strengthened his confidence in his state’s approach to water management. Prior appropriation, he said, is “the system that works in times of scarcity.”

More South Platte River Basin coverage here.