The Republican River Model and Conservation

According to a study (http://tinyurl.com/9fsks) issued by Kansas State University, most of the stream flow reduction that has occurred is the result of conservation practices.  Figure 1 is from a report issued by the Republican River Compact Settlement Conservation Committee in July 2005.  The initial report indicates that over 1.5 million acres in the Republican River Basin have been terraced.  This is more land than is irrigated.  It is obvious, from the Kansas State report and from the number of terraced acres, that removal of the terraces could bring Nebraska back into compliance by increasing the stream flow and, hence, the water supply.  However, removal of the terraces would also increase erosion and flooding.  The terraces cannot be removed without modification of Federal programs that regulate soil management.  So, while terraces are one of the primary causes of reduced stream flow, the removal of the terraces is an unacceptable solution.

Right now, the Model used by the Republican River Compact Administration to determine compliance does not take into consideration the effects of conservation.  As a result, the Model assumes that a reduction in stream flow is the result of groundwater irrigation.    As most people realize, this is inaccurate.  However, there is a legitimate reason the Model does not consider this.  In fact, the effects of conservation were intentionally left out of the Model.

If the compliance formulas factored in conservation, which is a consumptive use caused by man, then the depletions caused by man would greatly exceed the allocation available.  In other words, the conservation practices would eliminate any water being available for groundwater irrigation.  By ignoring one major element of the formula, the States agreed to permit the continued use of irrigation.

The Formula

VWS   = Virgin Water Supply

CU      = Consumptive Use = Depletions Caused by Man

CUp    = Consumptive Use caused by Groundwater Pumping

CUc    = Consumptive Use caused by Conservation 

CUv     = Consumptive Use caused by non-crop Vegetation

According to the Agreement, the following formula is used:

VWS minus CUp must be greater than 0.

In reality, nature uses the following formula:

VWS minus CUp minus CUc minus CUv must be greater than 0.

The Model sets CUc at 0 when, in reality, the number is larger than CUp.  The Model also vastly underestimates CUv.

A farmer looking at the Model says, “Hey, if you want to make me responsible, shouldn’t you also recognize that CUv and CUc are also responsible?”   The person running the Model says, “If we accurately accounted for Conservation and Tree Growth, there wouldn’t be any water left in the formula for you.  So by setting these at zero or by vastly underestimating them, we are doing the farmer a favor.”  Actually, the Modeler doesn’t say this; they just assume that it is too complicated for anyone but them to understand.

The Modelers feel like they have done the irrigator a favor by tinkering with the formula and ignoring reality.  The Modeler assumes that if conservation and vegetation were taken into consideration, irrigation would have to stop.  There are other options but not any that a Modeler can see.

If the Settlement Agreement were changed to accurately reflect reality, then the State would have been forced to make a decision.  Does it choose to permit irrigation and keep conservation practices, or do they shut down most irrigation and eliminate conservation practices, recognizing that the only way to return to the utopian world of streams that run like they did before Europeans arrived is to remove all activities of man?

Instead, the States chose to ignore reality and let groundwater irrigation continue but make it responsible for any deviations from utopia.  Because the formula ignores conservation and vegetation growth since 1950, only groundwater irrigation is seen as responsible for continued declines in the streams.  The Agreement says that there should be X amount of water in the stream, based on an estimate of how much water would be there had there been no humans.  It expects past human activity to cause the stream to continue to decrease in flow.  This is called the Lag Effect.  From 2003 on, groundwater irrigators will be responsible for compensation to the stream necessary to restore the stream to the 2003 level.   The Modelers realize that even if every irrigation well is turned off, there will still be a negative effect on the stream due to the vegetation growth, conservation practices, and groundwater pumping that happened decades ago.  Even so, only irrigation is responsible for replenishing the stream.

I do not believe most people understand how this works.  Many water policy makers insist that if we just reduce irrigation a bit, we will be at a sustainable level and life will go on.   In reality, the Agreement results in about a 1% increase in Consumptive Use each year and, hence, a continual reduction in the amount of water that can be used.  After 50 years, almost no irrigation will be permitted due to the Agreement.

How do we resolve this?  The people of the region and the State have to decide what is more important to them.  Do they want to use the water until it is gone, gradually shutdown irrigation, or move water from areas of surplus to areas of need?  Those are the three choices.  The majority of people in water policy positions have decided to gradually shut down irrigation.   If you believe a different solution is better, then the only way to make that happen is to replace the people who are in water policy positions.