State used 104,089 acre feet too much water

Wednesday, June 28, 2006

The Nebraska Department of Natural Resources has completed its preliminary calculations for the Republican River Compact in 2005. These DNR calculations show that while the continuing conservation efforts by farmers, irrigation districts and natural resource districts the state are making a positive impact, years of ongoing drought continue to strain the Nebraska allocation of water for consumptive use from the Compact.

Although Nebraska's consumptive use of water has stabilized and even decreased over the past three years, the amount of water allocated for use by Nebraska decreased each year due to decreased stream flows. The amount of water allocated to Nebraska in 2005 was the lowest in the history of the multi-state Compact.

Signed by the states of Colorado, Kansas and Nebraska in 1943, the Compact includes formulas allocating a certain percentage of the basin's water supply to each state. Water supplies vary from year to year, depending on weather conditions. The amount allocated to Nebraska varies from a low of around 200,000 acre-feet to a high of more than 400,000 acre-feet. The Compact regularly restricts each state's use of water to a five-year running-average allocation. Compact accounting for the five-year running average began in 2003, so the first year check for compact compliance will be based on allocations and consumptive uses for the years from 2003 to 2007, most of which have been dry.

In water-short years the states must restrict their consumptive usage to no more than a two-year average allocation. The U.S. Bureau of Reclamation makes the formal declaration of water-short years on June 30 annually, provided the irrigation supply from Harlan County Lake is less than 119,000 acre-feet. Due to ongoing drought, 2005 was declared a water-short year. The latest projected irrigation supply in the lake for 2006 is only 15,700 acre-feet, which indicates that 2006 is also likely to be declared a water-short year. Thus it is expected that Kansas and Nebraska will be restricted once again to two-year average allocations for the years 2005 and 2006.

Because the allocations depend on the amount of water available for the year, calculations to determine the allocations and consumptive use cannot be done until one year after the actual water use. Although the three compact states are still developing the final numbers for the Republican River Compact Administration, preliminary estimates indicate that the allocated water supply for Nebraska for 2005 was 199,420 acre-feet, the consumptive use of water was 253,540 acre-feet, and the credit Nebraska receives from water imported from the Platte River basin is 12,091 acre-feet. That leaves the shortfall between Nebraska's allocated supply and the consumptive use at 42,029 acre-feet. Combining these numbers with the numbers from 2003 and 2004 indicates that Nebraska's total allocation, with the credit for imported water for 2003-2005, was 664,881 acre-feet, and the state's total consumptive use was 768,970 acre-feet for the same period. Based on those three years of data, Nebraska's consumptive use appears to have been a total of 104,089 acre-feet over its allocation

The impact of the drought is clearly evident in these numbers, as are the concerted and cooperative efforts of Natural Resource Districts and farmers to conserve water. Although Nebraska's consumptive use on average decreased by 4,620 acre-feet per year between 2003 and 2005 the credit from imported water supply increased by an average of 1,155 acre-feet per year. The amount of water allocated to Nebraska decreased by an average of 12,924 acre-feet per year, due in large part to lower-than-normal precipitation

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