Stop the Decline of the Aquifer

The horizontal movement of water is very slow.  The aquifer is not like a lake it is more like a bathtub full of rock, sand, and dirt.  The slope of the shale layer under the aquifer is less than the slope of the typical bathtub.  All of that rock, sand, and silt tends to hold onto the water.  The gravity pulling down is much greater than the gravity pulling to the side. The point is this.  Aquifer levels are influenced by irrigation and precipitation events at the field where they happen.  The time it takes for precipitation to move horizontally underground is very slow. 

This map shows what the USGS says is the recharge rate. The map implies that we are pumping twice the average recharge.  To stop the aquifer decline we could reduce the pumping by 50% and the total recharge for the District would then about equal the total pumping for the District.  However, this would not stop the decline in many parts of the District. 

The darker blue areas match up pretty well with where the sandy soil is in the District.  Comparing the areas with the best recharge with where the irrigated acres are will help identify what happens if we reduce the allocation.

A strict 6 inch allocation on each acre would cause the total water balance for the District to equalize.  However, we would still see areas with aquifer declines within the District.

Because there are areas where the irrigated acres are concentrated and because the horizontal movement of underground water is slow, even a 6 inch allocation will see a continued decline in the aquifer in those areas.

To stop the aquifer decline we must set the irrigation allocation below the recharge rate.  Setting it equal to the recharge rate will not be enough because the seepage from the aquifer into the stream will drain the aquifer.   

If the goal is to stop aquifer decline in most sections of the District, then one needs to set the allocation to a bit less than the recharge rate.  Just because there are fewer irrigated acres in eastern Chase and Dundy Counties does not mean that the precipitation there will recharge the aquifer in the western half of Chase County.

So when someone says they want to stop the aquifer decline find out exactly what they mean.  Do they mean stop the decline under each irrigated acre.  That is usually what they mean but few realize that to accomplish their stated goal they must shut off most irrigation wells in the District.

This is where declines are currently happening.  Compare it with where the irrigated acres are.