2017 Attachment O Customer Meeting October 28, 2016

Agenda Meeting Purpose Otter Tail Power Company Profile Attachment O Calculation Capital Projects Budget Risks Question/Answer

Legal Disclosure All numeric data provided in this presentation is preliminary and subject to change. All information will be finalized by 12/31/16.

Meeting Purpose To provide an informational forum regarding Otter Tail’s forecasted Attachment O for 2017. The forecasted Attachment O for 2017 is calculated using the FERC Form 1 Attachment O template under the MISO Tariff with a projected net revenue requirement and projected load. Rates to become effective on January 1, 2017 for the joint pricing zone comprised of Otter Tail, Great River Energy, Missouri River Energy Services, Benson Municipal Utilities, Detroit Lakes Public Utilities, and Alexandria Light & Power. The schedules provided herein reflect the recent FERC order approving a 10.32% ROE, plus a 50 basis point adder that OTP has been granted.

Service area NORTH DAKOTA SOUTH DAKOTA 70,000 Square miles 131,149 Customers 421 Communities Avg. population about 458 770 Employees 445 Minnesota 210 North Dakota 115 South Dakota About 800 MW owned generation About 245 MW wind generation About 5,300 miles of transmission lines Service area LANGDON WIND ENERGY CENTER Rugby Devils Lake Crookston Garrison SOLWAY COMBUSTION TURBINE Bemidji COYOTE STATION LUVERNE WIND FARM ASHTABULA WIND ENERGY CENTER Jamestown ASHTABULA III JAMESTOWN COMBUSTION TURBINE NORTH DAKOTA Fergus Falls Wahpeton HOOT LAKE PLANT Oakes SOUTH DAKOTA Morris BIG STONE PLANT Milbank LEGEND Headquarters Customer service center LAKE PRESTON COMBUSTION TURBINE

Our mission To produce and deliver electricity as reliably, economically, and environmentally responsibly as possible to the balanced benefit of customers, shareholders, and employees and to improve the quality of life in the areas in which we do business.

Our Vision Growth and success—for our company and the rural communities we serve. We collaborate and prosper through responsible, resourceful action. We balance community, economic, and environmental commitments. Always.

Our VALUES INTEGRITY We conduct business responsibly and honestly. SAFETY We provide safe workplaces and require safe work practices. CUSTOMER FOCUS We provide reliable electricity and timely, courteous customer service. COMMUNITY We care about the people and places we serve and improve the quality of life in the areas in which we do business. RESOURCEFULNESS We draw on the ingenuity and expertise of various resources to create strategic, balanced, practical plans.

Attachment O Calculation

Forward Looking Attachment O Forward Looking Rate Requirements Rate Base Operating Expenses Revenue Requirement and Rates Network Rate Summary

by November 1 of each year. RATE REQUIREMENTS Actual By June 1 of each year, Otter Tail will post on OASIS all information regarding any Attachment O True-up Adjustments for the prior year. By September 1 of each year, Otter Tail will hold a customer meeting to explain its Actual Year True-up Calculation. Ex., 2016 Forward Looking Attachment O will be trued-up by June 1, 2017 with a corresponding Customer Meeting to be held by September 1, 2017. Forward Looking By September 1 of each year, Otter Tail will post on OASIS its projected Net Revenue Requirement, including the True-Up Adjustment and load for the upcoming year, and associated work papers. A customer meeting will be held by October 31 of each year to explain its forward looking formula rate input projections and cost detail. The MISO Transmission Owners will hold a Regional Cost Sharing stakeholder meeting by November 1 of each year.

RATE BASE Note: The above numbers are Transmission only

OPERATING EXPENSES Note: The above numbers are Transmission only

REVENUE REQUIREMENT AND RATE

Rate Summary Note: Displayed above are the primary drivers of the change between years. Other drivers may include but are not limited to: operating expenses, depreciation, property taxes, income taxes, revenue credits, allocation factors etc.

TOTAL TRANSMISSION REVENUE REQUIREMENT BREAKDOWN Total Rev. Req. = $69,008,580 Net Attch. O ATRR = $29,349,109 Attch. GG Rev. Req. = $17,557,871 Attch. MM Rev. Req. = $22,101,600

2017 transmission Projects

ATTACHMENT O CAPITAL PROJECTS: TRANSMISSION LINE PROJECTS > $250K

ATTACHMENTS GG AND MM CAPITAL PROJECTS: TRANSMISSION LINE PROJECTS > $250K

Timing of Capital Projects Budget Risks Revenue Demand/ Weather Regulatory Filings Financing Outages Timing of Capital Projects

Manager – Regulatory Administration Questions? If you have any additional questions after the meeting, please submit via e-mail to: Stuart Tommerdahl Manager – Regulatory Administration stommerdahl@otpco.com All questions and answers will be distributed by e-mail to all attendees. Additionally, the questions and answers will be posted on Otter Tail’s OASIS website (http://www.oasis.oati.com/OTP/index.html) within two weeks from the date of inquiry.