Transmission System Customer Discussions – July 2009 Common Use System (CUS) Black Hills Power Basin Electric Power Cooperative Powder River Energy Corporation Prepared July 14, 2009

Agenda Introductions Common Use System Overview Basin Electric Costs Transmission Rate Case Schedule Customer Impacts Discussion / Questions

S DAKOTA NEBRASKA WYOMING MONTANA BUFFALO CASPER DAVE JOHNSTON SPEARFISH RAPID CITY HOT SPRINGS RENO SHERIDAN TECKLA STEGALL YELLOWCAKE S. RC Y. CRK HUGHES DC TIE CARR DRAW B. CRK M. MILE OSAGE SPENCE PUMPKIN BUTTES WYODAK PacifiCorp System WAPA System Regional Transmission System - Existing Common Use System LRS

S DAKOTA NEBRASKA WYOMING MONTANA BUFFALO CASPER DAVE JOHNSTON SPEARFISH RAPID CITY HOT SPRINGS RENO SHERIDAN TECKLA STEGALL YELLOWCAKE S. RC Y. CRK HUGHES DC TIE CARR DRAW B. CRK M. MILE OSAGE TONGUE RIVER ARVADA SPENCE PUMPKIN BUTTES Donkey Creek WYODAK Common Use System (new) PacifiCorp System WAPA System Regional Transmission System - New Common Use System MVAr’s D-VAR 2009 “DJ AREA” LRS 2010 (BH)

Cost of Equity Cost of Debt General Plant Allocator Capital Projects Potential Future Facilities Basin Electric Costs

Cost of Equity – 10.80% Cost of Debt General Plant Allocator Capital Projects Potential Future Facilities Basin Electric Costs

Cost of Equity – 10.80% Cost of Debt – 5.95%(2009); 6.08%(2010) General Plant Allocator Capital Projects Potential Future Facilities Basin Electric Costs

Cost of Equity – 10.80% Cost of Debt – 5.95%(2009); 6.08%(2010) General Plant Allocator – GP1 per settlement Capital Projects Potential Future Facilities Basin Electric Costs

Cost of Equity – 10.80% Cost of Debt – 5.95%(2009); 6.08%(2010) General Plant Allocator – GP1 per settlement Capital Projects – $82.9m  $87.6m Potential Future Facilities Basin Electric Costs

Cost of Equity – 10.80% Cost of Debt – 5.95%(2009); 6.08%(2010) General Plant Allocator – GP1 per settlement Capital Projects – $82.9m  $87.6m Potential Future Facilities Generation Interconnection Network Facilities Other? Basin Electric Costs

FERC Filing – August 1, 2009 (July 31, 2009) Effective Date – October 1, 2009 Compliance Filing – After end of Calendar year 2010, prior to June 1, 2011 Transmission Rate Case Schedule

Estimate Revenue Requirement of $18.23 million Rate Impacts

2009 rate - $2.03 / kW-month Black Hills$ 9.41 m Basin Electric m PRECorp 1.30 m Revenue Credits (0.20) m Total m Usage – 980 MW Rate – $2.03 / kW-Month Rate Impacts

2010 rate - $2.38 / kW-month Black Hills$ 9.41 m Basin Electric m  PRELIMINARY PRECorp 1.30 m Revenue Credits (0.20) m Total m Usage – 1,005 MW  PRELIMINARY Rate – $2.38 / kW-Month Rate Impacts

Discussion / Questions