AN UPPER BASIN PERSPECTIVE The Colorado River Basin Study of 2012 Don Ostler – Upper Colorado River Commission
Upper Basin Conditions • 1922 Compact promises UB 7.5 maf of use • UB uses have reached 4.8 maf • Current estimated safe yield for UB is only about 6 maf • Climate impacts are an additional uncertainty • Areas of the UB are experiencing rapid growth
Upper Basin Conditions cont. • UB has already adjusted plans to reflect reality • Count evaporation losses against our allowed uses • Count all tributary uses as part of System Uses • Count all ground water uses as part of total use • Has a plan for future development based upon estimates of safe annual yield -The LB and UB greatly benefit from the above decisions -The LB currently does not count uses in the above manner
Upper Division Shortages Occur regularly due to variation in annual precipitation and lack of storage. Have occurred each year since 2002. Have ranged from at least 630,000 acre-feet to small shortages since 2002. Average annual shortage in the Upper Division has been approximately 380,000 acre-feet since 2002.
Current Conditions • Lake Powell currently at 46% of capacity • Forecasted inflow for WY 2013 is 41% of average • Powell expected to drop by another 20 ft. by Jan. • Lake Mead is currently about 47% of capacity • Projected Powell release for next year? • Release volume will likely drop from 8.23 to 7.48maf • Powell less than 3575 ft and Mead at or above 1025ft • Models have over-predicted Powell elev. by ave. of 5 ft
AN UB VIEW OF THE STUDY • The UB States do not presently use their full entitlement of Colorado River water under the Compact • Little chance of curtailment under historically observed or tree ring hydrology even with increases in use • Increased water use in UB is not the predominant driver of curtailment risk – significantly dryer climate assumptions are!
UB VIEWS CONTINUED • There is much more uncertainty associated with climate based stream flow assumptions • The UB is initiating planning to address climate based risk. Even if drier climate predictions occur, the UB can still develop a considerable amount of additional water
UB VIEWS CONTINUED • The most pressing Colorado River issue is the supply and demand imbalance in the lower basin. Existing demand levels are more than the River can support. • Shortages in the Lower Basin will become more frequent and greater as demand in the UB increases • With coordinated reservoir operations, shortages in the lower basin also affect the UB.
CONCLUSIONS • We must immediately begin to take the additional steps needed to address the supply and demand issues • All Colorado River Basin States must participate in efforts to find the policy and infrastructure solutions to address these issues