Friday, May 6, 2011

If I Install a More Efficient Irrigation System, Can I Irrigate More Acreage?

The question is often asked: If I put in a more efficient irrigation system, can I increase my irrigated acreage (or sell the "saved" water)? Unfortunately, the answer is generally no. The reason why is somewhat complex, but I've summarized in the following explanation and example.

In Utah, beneficial use is the basis, measure, and limit of a water right. The water right has several characteristics, including diversion and depletion limits.

For this example, assume that your water right permits you to irrigate 10 acres and that the the irrigation duty in your area is 4 acre-feet per acre. The water right, in terms of acre-feet, would be 40 acre-feet. The duty, however, is based on flood irrigation, which is not very efficient. The general rule for flood irrigation is that 50% of the water is depleted (i.e., used) and the other 50% returns to the natural system (as runoff, tailwater, or seepage into the underground aquifer). Assuming you flood irrigate, you would likely divert all 40 acre-feet in order to irrigate the 10 acres, but you would only be depleting 20 acre-feet (with the other 20 acre-feet being returned to the natural system). These are the limits of use for your water right: a diversion limit of 40 acre-feet and a depletion limit of 20 acre-feet.

Now assume you install a very efficient sprinkler system. Because the system is so much more efficient than flood irrigating, you only have to divert 22 acre-feet to irrigate the same 10 acres. It would appear that you "saved" 18 acre-feet, which you could use to irrigate 8 more acres. However, doing so would increase the depletion. When you were flood irrigating, you depleted 20 acre-feet; however, with the new system and expanded acreage, you would be depleting 36 acre-feet.

It is for this reason the Utah State Engineer will not allow “spreading” of water based on more efficient systems. The State Engineer believes that the increased depletion would be an enlargement of your water right and would adversely affect other water users. (Additionally, because your water right is limited to the irrigation of 10 acres, expanding the irrigated acreage to 18 acres would enlarge your water right.)

The current State Engineer, Kent Jones, has talked about this topic several times recently. It seems to be one of his primary concerns. If you go to this web address and click on "Presentation - Kent Jones," you can see a PowerPoint slideshow from one of his recent presentations. Slides 13-20 specifically address this issue.


Dave Brown said...

Is there any difference in this situation if a person owns water shares instead of a water right?

Jeff Gittins said...

Under the current view of the Division of Water Rights, there would not be a difference. Suppose, for example, that an irrigation company has water rights that allow the company to irrigate a total of 100 acres. The company has issued 100 shares, meaning that each share entitles the share owner to irrigate 1 acre. One shareholder, who owns 25 shares and irrigates 25 acres, puts in a more efficient irrigation system. Due to the efficiency, the shareholder then irrigates 50 acres instead of 25 acres. The result is that the company, as a whole, is now irrigating 125 acres, even though it only has the water rights to irrigate 100 acres. The depletion would also have increased. The Division would view the company as exceeding its water rights, and could take enforcement actions against the company.