During April-May 2011, the Upper Big Blue NRD measured 484 observation wells throughout the district and then averaged the data of all these wells. Observation wells are measured in the spring of each year, allowing the water table to rebound from the previous irrigation season.
Overall, the spring 2011 average measurement for the groundwater level change shows a rise of 1.27 feet from spring 2010.
The findings also show that the spring 2011 average groundwater level is 7 feet above the "allocation trigger," the level at which pumping allocations would have to be begin in this district of more than 1 million irrigated acres. That's approximately 15% of the state's total irrigated acres.
When the Upper Big Blue NRD began measuring groundwater levels in 1961, there were approximately 300,000 acres of irrigated land throughout the District. Today, the district totals 1.1 million irrigated acres. Overall, since 1961, the average groundwater level has risen one-half foot from 1961-2011 even with an increase of 800,000 irrigated acres over that same period of time.
Through the conservation efforts of groundwater users, and because of an extended period of above average rainfall in the 1980s and 1990s, the average groundwater level in the Upper Big Blue NRD rose significantly to a level in the year 2000 that was approximately 7 feet higher than the 1961 level (baseline), and 14 feet higher than the low level of 1976 to 1981.
The NRD's goal is to hold the average groundwater level to above the 1978 level. In 2007, the district average groundwater level reached the "reporting trigger," initiating groundwater users to report annual groundwater use and to certify their irrigated acres. If the NRD average level falls below the 1978 "allocation trigger level," the use of flow meters will be required and groundwater allocation will begin.
The Upper Big Blue NRD rules and regulations mandate that producers will be responsible for installing flow meters on existing wells if the groundwater level hits the allocation trigger. When the allocation trigger is reached and producers and other users have not installed flow meters by the next calendar year, then they will not be able to pump any amount of water until a flow meter is installed.Since March 1, 2004, all new wells and replacement wells have required a flowmeter.