La Plata Water Conservancy District and Longhollow Reservoir

After more than 20 years of planning, the La Plata Water Conservancy District approved an escrow agreement in mid-February that allows groundbreaking for Longhollow Reservoir. The reservoir will be located just five miles north of the New Mexico state line. It will store 5,400 acre-feet of water--300 of which will help to satisfy Colorado’s La Plata River obligation to New Mexico. The remainder is for irrigators in the arid southwest corner of La Plata County. According to a Durango Herald article, the water earmarked for New Mexico is a relief for Colorado, which is bound by a 1922 agreement on the division of La Plata River water. Colorado has to give New Mexico half the water in the river as measured at Hesperus from February 15th to December 1st when the flow at the state line is below 100 cubic feet per second. During the rest of the year there are no requirements. Historically, however, Colorado has a hard time making their compact obligations because the porous bed of the La Plata River and riparian vegetation suck up much of the flow. In some years, Colorado irrigation ditches have been shut off entirely to satisfy the agreement with New Mexico.