How much water is there?

 There was as much water in the aquifer in 1997 as there was in 1918.

Between 1918 and 1965 the aquifer volume increased by about 25,000,000 acre feet.  Between 1965 and 1997 there has been a decrease in the aquifer by about 25,000,000 acre feet.


Source: RRCA baseline simulation 1918-2003, 12p7.out                                                                     www.waterclaim.org

The aquifer is like a giant sponge.  It is filled by precipitation, seepage from irrigation and by leakage from the streams.  Water leaves the aquifer via springs and irrigation wells. 

Approximately 89 million acre feet of water have been removed from the aquifer via irrigation wells since 1918.  However, about 126 million acre feet has entered the basin from precipitation during the same time period.  Some of the precipitation is lost to evaporation (about 41 million acre feet).   Some runs off and into the stream.

According to the computer simulation that attempts to model water in the Basin, the largest increase in the volume of water entering the aquifer happened in 1965 and the largest decrease happened in 1976. 

Over the last 30 years the depletion of the aquifer has reduced from 900,000 acre feet per year to 690,000 acre feet per year.  This has happened even though more acres are now being irrigated than there were 30 years ago.  As of 2004 most of the Basin will have implemented restrictions on new wells and will limit the amount of water each well can use.  As more fields are converted from gravity irrigation to pivot irrigation additional saving should be realized.  And as invasive species are managed even greater amounts of water will get to the aquifer instead of being captured by non-productive plants.

Graph 2 shows the average volume of water by county.  The dark shaded area is the approximate amount of water in the aquifer in each county.  For example, Chase County had an average saturated thickness of 221 feet.  Since records have been kept, the aquifer has gone down about 28 feet across Chase County .  The average reduction over the last 10 years has been about 1 acre foot per year for most of the county.  The greatest amount of water is in the northeast corner of the county with about 400 feet of saturated thickness.  The least amount of water is also in the northeast corner with only 83 feet of water.  However, most of the county has about 200 feet of water under it. 

The south half of Dundy County never has had much water.  The average holding capacity of the soil there is about 45 feet.  The southern third of Dundy County has a very shallow aquifer layer that can only hold about 10 to 20 feet of water.  During the irrigation season this water is often removed from the aquifer and then it usually replenishes during the winter.  The south half of Dundy County uses less water than the other areas in the district because the wells there will not produce as much water.


Graph 2

Not all of that water can be used for irrigation.   The hydrologists estimate that about half of that water can be withdrawn by high capacity irrigation wells.  The rest is only accessible by small wells.  This means there will always be enough water for house and stock wells.  They will never go dry.

In the last 25 years Upper Republican NRD has reduced the amount of water it uses by about 40%.  This is due to more efficient irrigation methods and water restrictions that force careful management. 

Assuming we continue using water at the level we do now, most of the URNRD will be able to continue irrigation for many more years.  We are now at the level the aquifer was in 1918.  If we turned off all of the irrigation wells in the district, it is likely that the aquifer would return to its peak level of 1965 within 50 years.  Alternatively, we could import water into the Basin and recharge the aquifer.  This is permitted by the Tri-State Compact and the laws of Nebraska and is within the economic ability of the region.  About 2 million acre feet of water flow into Nebraska each year and about 8 million acre feet leave the state.  Nebraska loses about 6 million acre feet a year that usually end up as salt water in the Gulf of Mexico .

Once you know the facts you don’t have to be ruled by a state of fear.  The sky is not falling.  It is very possible to manage water so that it remains here for both us and for the future generations.