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Supplemental Information PGA Summaries: South Dakota Navigator PGA Summaries: 2009 | 2008 | 2007 Purchased Gas Adjustments During 2009 (per therm) Northern Natural Gas Company Revision No. Effective Date Clause 1 Clause 3* Small, Medium & Large Volume Firm Small & Large Volume Interruptible 158th Rev. Sh. No. 3 1/07/09  0.71640 .00000 159th Rev. Sh. No. 3 2/07/09  0.38726 .00000 160th Rev. Sh. No. 3 3/07/09  0.46674 .00000 161st Rev. Sh. No. 3 4/07/09  0.29445 .00000 163rd Rev. Sh. No. 3 5/07/09  0.23321 .00000 164th Rev. Sh. No. 3 6/07/09  0.21256 .00000 165th Rev. Sh. No. 3 7/07/09  0.23331 .00000 166th Rev. Sh. No. 3 8/07/09  0.20784 .00000 167th Rev. Sh. No. 3 9/07/09  0.35203 .00000 168th Rev. Sh. No. 3 10/07/09  0.46787 .00000 169th Rev. Sh. No. 3 11/07/09  0.54450 .00000 * Effective March 1, 2006, Interruptible PGA Clause 3 has been replaced with daily market gas prices. The daily market gas price will be applied to customers' daily consumption. Daily market prices for the previous month are posted on the Rates section on the Internet under Supplemental Information - Gas: Interruptible Commodity Prices. Navigator PGA Summaries: 2009 | 2008 | 2007 For Your Home | For Your Business | Safety | Rates | Energy Efficiency | Economic Development | Environmental Efforts About Us | Careers | News Room | Storm Center | Wind Energy | Contact | Streetlight Repair Request | System Outage Watch | Energy Choice | For Contractors | For Landlords | ©2009 MidAmerican Energy Holdings Company. All rights reserved.