Problem No. 9

Dear Editor,

Problem 9 with the Model -- Allocations Based on Stream Flow

The Model is supposed to be designed to measure the depletion to the stream caused by ground water irrigation. One of the ways this is done is to measure precipitation at 35 locations across the Basin and calculate how much water should have made it to the stream if irrigation did not intercept the run off.

If there is a rain event at one of the gages but there is no corresponding increase in stream flow, then the Model reports that irrigation caused the problem.

This was demonstrated in the last few years. The Republican River Basin suffered an extreme drought in 2002 and 2003. However, precipitation across the Basin was normal in 2004, 2005, and 2006, and above normal in 2007 and 2008. The normal precipitation that was received in 2004, 2005, and 2006 did not cause an increase in the stream flow. Why? The Model says that it was irrigation that caused the failure. Yet, stream flow is strongly influenced by many things in addition to precipitation. These include the time of year the water falls, how far from the stream it falls, conservation practices in the area, and the vegetation present.

Nebraska has constructed 2-foot-high dams on more than 2 million acres. Each is designed to capture water and make it available to the vegetation near the terrace. These terraces play a larger role in stream flow than does irrigation, according to Kansas State University; but, the Model ignores this reality. Each acre of terraces captures several inches of water. Some of this water is used by plants and lost to the stream. Some seeps into the ground and arrives at the stream months or years later. Even if this loss to plants is only an inch for each acre, then the terraces use more water than all other water users.

The DNR says that even though conservation practices are not measured, that the effects of conservation are parsed out of the data before the model is run. That does not appear to be true. Willfully excluding conservation from the formulas used in the model requires something to pickup the difference to make the system balance. That something is groundwater.

Huge trees all along the streams and tributaries have grown up over the decades. These trees consume more water than corn does, yet the model ignores most of the effects this vegetation has on stream flow.

Contrary to what many think, there is very little correlation between precipitation and the amount of water Nebraska is allowed to use. The real measure of what Nebraska is allowed to use is based on how much water is actually in the stream. If there is a lot of water in the stream, then the Model permits the State to use a lot of water. If there isn't, then it says it is irrigation's fault and Nebraska is charged for overuse.

Steve Smith,

WaterClaim.org.

Imperial