Idaho Public Utilities Commission

Case No. PAC-E-11-06, Order No. 32173

March 1, 2011

Contact: Gene Fadness (208) 334-0339, 890-2712



Utility seeks changes to irrigation load control program


The Idaho Public Utilities Commission is taking comments through March 23 on a proposal by Rocky Mountain Power (RMP) to make changes to a program that credits irrigators for reducing their consumption during periods of peak electrical use.


From June 1 to Aug. 31, RMP can turn off the pumps of irrigators who agree to participate in the program from 11 a.m. to 7 p.m., as long as the utility provides prior-day notification. The curtailment to volunteer irrigators helps RMP meet electrical demand during periods of peak use and prevents the company from having to find more costly power to meet demand. Irrigators can decline to participate in some of the curtailments, but the credit they are paid by the company is reduced for each curtailment incident for which the irrigator decides to opt out. Curtailment cannot exceed 52 hours for any participant.


Rocky Mountain Power claims the rapid growth of the program – from 65 megawatts of participating load when it began in 2007 to 278 MW of participation in 2010 – is creating voltage control problems when the program is at full use, with some circuits experiencing unacceptable increases. During 2010, RMP implemented a phasing process to ramp load off and back during dispatch events, but the size of the loss of load was still beyond the voltage equipment’s ability to compensate, the company claims.


To respond to the voltage issues, Rocky Mountain seeks to be allowed to reject prospective program participants for reasons of cost-effectiveness and impact on the company’s transmission and distribution system. It also wants to reduce the credit irrigators receive from $30 per kilowatt per year to $25.30 per kW per year.  The company also proposes to modify the penalty irrigators receive for opting out of scheduled curtailments.


Comments are accepted via e-mail by accessing the commission’s homepage at and clicking on "Comments & Questions About a Case." Fill in the case number (PAC-E-11-06) and enter your comments. Comments can also be mailed to P.O. Box 83720, Boise, ID 83720-0074 or faxed to (208) 334-3762.


A full text of the commission’s order, along with other documents related to this case, is available on the commission’s Web site at Click on “File Room” and then on “Electric Cases” and scroll down to the above case number.