Exhibit 99.1

NEWS RELEASE

Media contact:	Amy Richardson, Director of Communications, (701) 451-3580 or (866) 410-8780
Investor contact:	Loren Hanson, Director of Shareholder Services, (218) 739-8481 or (800) 664-1259
Dateline:	Fergus Falls, Minnesota
For release:	February 6, 2006	Financial Media

Otter Tail Corporation Surpasses $1 Billion in Revenues and Reports Record Earnings for 2005; Board Approves Dividend Increase

Otter Tail Corporation (NASDAQ: OTTR) announced financial results for the year ended December 31, 2005, with the following highlights:

• Consolidated net income from continuing operations increased to $52.9 million for 2005 compared with $40.6 million in 2004.

• Total consolidated net income increased to $62.6 million for 2005 compared with $42.2 million for 2004.

• Total diluted earnings per share increased to a record $2.11 for 2005 compared with $1.58 for 2004.

• Total diluted earnings per share in 2005 include a net gain of $0.34 per share from the sale of three businesses.

• Diluted earnings per share from continuing operations increased to $1.78 for 2005 compared with $1.52 for 2004.

• Consolidated revenues grew 22% to $1.05 billion in 2005 compared with $857 million in 2004.

2006 announcements include the following:

• On February 6, 2006 the Board of Directors declared a quarterly common stock dividend, increasing the dividend to $0.2875 per share from $0.28 per share paid in the fourth quarter of 2005. This increase puts the corporation’s current dividend yield at 3.8%.

• The corporation anticipates its 2006 diluted earnings per share from continuing operations to be in the range of $1.60 to $1.80.

“Our financial results in 2005 were exceptional. Revenues surpassed $1 billion for the first time in our history and we achieved a record level of earnings,” said John Erickson, president and chief executive officer of Otter Tail Corporation. “The strong performance reflects earnings growth in both our electric and nonelectric operations. Our electric business adapted well to redesigned wholesale energy markets introduced in 2005, and our nonelectric

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operations were led by record results at our plastics companies. Additionally, the sale of Midwest Information Systems provided a significant positive one-time impact on 2005 results. Looking ahead, we expect 2006 to be a solid year for our continuing operations.”

Erickson said dividend payments will again increase in 2006 and at a higher rate. “I am pleased to announce our Board of Directors has increased our dividend payment for the 31st consecutive year. The increase brings the annual indicated dividend rate to $1.15 per share, a $0.03 increase over the 2005 rate.” The $0.03 increase is reflective of the corporation’s successful financial results, inclusive of the net gain on the sale of businesses in 2005.

Segment Performance Summary

Electric

Net income in the electric segment increased in 2005 to $37.3 million compared with $31.5 million in 2004. Electric revenue increased 17.5% to $313.0 million in 2005 from $266.4 million in 2004, reflecting a $24.6 million increase in retail electric revenue, a $19.2 million increase in wholesale energy and mark-to-market revenues and a $2.8 million increase in other electric revenue. The increase in retail revenue includes $16.0 million in increased cost-of-energy adjustment revenues and $8.6 million in increased revenue from a 3.2% increase in retail kilowatt-hour (kwh) sales. Kwh sales to commercial customers increased 3.7% related to an improving regional economy. Residential kwh sales increased 3.9% primarily due to an 86% increase in cooling degree-days in the summer of 2005 compared with the summer of 2004. Revenues from wholesale energy sales from company-owned generation increased $6.8 million. This increase is due to a 58.9% increase in the average price per kwh sold in 2005 compared with 2004, offset by a 13.2% reduction in kwh sales. This increase in the average price per kwh is reflective of a general increase in energy prices in 2005. Net revenues from the purchase and sale of electric energy contracts and financial transmission rights in 2005 increased $12.4 million, including a $1.2 million increase in mark-to-market gains on forward energy contracts, as compared with 2004 net revenues from energy trading activities. The $2.8 million increase in other electric revenues is related mostly to transmission line permitting work completed by Otter Tail Power Company for the Midwest Independent Transmission System Operator (MISO).

In December 2005, the Minnesota Public Utilities Commission (MPUC) issued a decision to disallow recovery of certain MISO-related costs through the fuel clause adjustment in Minnesota retail rates. A $1.9 million reduction in revenue and a refund payable was recorded in December 2005 for amounts collected from Minnesota retail customers under interim guidance provided by the MPUC after the inception of MISO electric markets in April 2005. A final decision on the status of this refund payable has been deferred pending a rehearing by the MPUC.

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Electric operating expenses increased $36.9 million, which includes increases of $22.6 million in fuel and purchased power expenses and $14.2 million in electric operating and maintenance expenses. Fuel costs increased $3.9 million, reflecting a 15.5% increase in the cost of fuel per kwh generated, partially offset by a 7.0% reduction in generation. Purchased power costs to serve retail customers increased $18.7 million as a result of a 28.5% increase in kwh purchases combined with a 14.1% increase in the cost per kwh purchased. The decrease in kwh generation is mainly due to the seven-week maintenance shutdown of Big Stone Plant in the second quarter of 2005. Kwh purchases increased to make up for the shortfall caused by the Big Stone Plant shutdown and to provide for increased demand. The increase in electric operation and maintenance expenses in 2005 reflects a rise in labor and benefit costs, and additional expenses related to external contract work, required repairs due to damage from three major storms and Big Stone Plant maintenance updates.

Plastics

The plastics segment revenues and net income were $158.5 million and $13.9 million, respectively, in 2005 compared with $115.4 million and $5.7 million in 2004. The increase in revenue and net income reflect the effect of rising resin prices and increased customer demand for PVC pipe. Demand accelerated to record levels late in the third quarter of 2005 as substantial resin price increases were announced and concerns developed over the adequacy of resin supply following the 2005 Gulf Coast hurricanes. A majority of U.S. resin production plants are located in this region.

Manufacturing

The manufacturing segment’s revenues and net income were $244.3 million and $7.6 million, respectively, in 2005 compared with $201.6 million and $7.6 million in 2004. DMI Industries, Inc., the corporation’s manufacturer of wind towers and structural steel products, recorded a $23.8 million increase in revenue due to increased production and sales activity. This is in part related to the production tax credits for wind-generated electricity being in place for 2005 as well as improvements in productivity and capacity utilization. DMI’s net income increased $2.0 million as a result of the above-mentioned items. At T.O. Plastics, Inc., the corporation’s manufacturer of thermoformed plastics and horticultural products, revenues increased $3.8 million and net income increased $0.7 million as a result of productivity improvements and higher prices that provided for recovery of increased raw material costs. At the corporation’s manufacturer of waterfront equipment, ShoreMaster, Inc., revenues increased $4.9 million due to the acquisitions of Shoreline Industries and Southeast Floating Docks, offset in part by a decline in revenues in its residential and commercial divisions. Net income decreased $1.0 million between 2005 and 2004, mainly as a result of increases in material costs which were not passed on to customers, higher administrative wages and benefit costs, and increases in interest costs and depreciation expense. At BTD Manufacturing, Inc., the corporation’s metal fabrication business, revenues increased $10.2 million while net income decreased $1.8 million mainly as a

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result of material and production cost increases. The increase in BTD revenues mainly reflects recovery of a portion of higher raw material and production costs plus additional sales related to the 2005 acquisition of Performance Tool & Die, Inc.

Health Services

The health services segment’s revenues and net income were $124.0 million and $4.0 million, respectively, in 2005 compared with $114.3 million and $3.0 million in 2004. Scanning and other related service revenues increased $13.9 million while revenues from equipment sales and service decreased $4.2 million between the periods. The revenue per scan and the number of scans completed increased 9.6% and 5.9%, respectively. The imaging business added to its fleet of medical imaging equipment in 2005. Improved operating efficiencies in the imaging business and service cost reductions initiated in 2004 along with growing scan counts have contributed to improved results in the health services segment.

Food Ingredient Processing

Results in 2005 for the corporation’s food ingredient processing segment, established with the acquisition of Idaho Pacific Holdings, Inc. (IPH) in August 2004, include operating revenues of $38.5 million and net income of $0.33 million compared with operating revenues of $14.0 million and net income of $0.35 million from 19 weeks of operation in 2004. Consistent with trends in the industry, net income was less than expected as a result of lower sales volume and prices, high energy costs, increasing raw material costs and the increasing value of the Canadian dollar relative to the U.S. dollar. Net income in the fourth quarter was also negatively impacted by a $0.7 million increase in income tax expense in 2005 related to an adjustment to deferred income taxes payable at IPH’s Canadian subsidiary, Agrawest, as a result of the government of Prince Edward Island rescinding a previously granted tax credit of 8.5% of taxable income.

Other Business Operations

Other business operations had a net loss of $10.3 million in 2005 compared with a net loss of $7.4 million in 2004. This $2.9 million loss increase includes a $1.0 million goodwill impairment write-off at the corporation’s energy services subsidiary as a result of a reassessment of its future cash flows in light of rising natural gas prices and greater market volatility in future prices for natural gas. Increases in the corporation’s employee health insurance costs and other employee benefit costs and increases in insurance costs at the corporation’s captive insurance company contributed $1.9 million to the increase in net losses in this segment.

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Discontinued Operations

Discontinued operations includes the operating results of Midwest Information Systems, Inc. (MIS), a telecommunications company located in Parkers Prairie, Minnesota, St. George Steel Fabrication, Inc. (SGS), a structural steel fabricator located in St. George, Utah, and Chassis Liner Corporation of Alexandria, Minnesota, a manufacturer of auto and truck frame-straightening equipment and accessories. The sales of MIS and SGS were completed in the second quarter of 2005. The sale of Chassis Liner was completed in the fourth quarter of 2005. The corporation recorded a net-of-tax gain on the combined sales of $10.0 million ($0.34 per diluted share) in 2005. The sale of MIS produced an after-tax gain of $11.9 million. This gain was offset in part by a combined loss on the sales of SGS and Chassis Liner of $1.9 million. The net loss from operations for all three companies was $0.3 million in 2005 compared with net income of $1.6 million in 2004.

Fourth Quarter Results

Diluted earnings per share from continuing operations for the fourth quarter of 2005 were $0.42 compared with $0.51 for the fourth quarter of 2004. Total diluted earnings per share for the fourth quarter of 2005 were also $0.42 compared with $0.55 for the same period in 2004. Revenues for the fourth quarter of 2005 were $285.2 million compared with $239.6 million for the same period a year ago. Operating income for the fourth quarter of 2005 was $23.3 million compared with $24.1 million for the fourth quarter of 2004. All segments except plastics showed decreases in net income in the fourth quarter of 2005 compared with the fourth quarter of 2004.

Dividend Increase for 2006

On February 6, 2006 Otter Tail Corporation’s Board of Directors increased the quarterly dividend on the corporation’s common stock to $0.2875 per share, up from $0.28 per share paid in the fourth quarter of 2005. This dividend is payable March 10, 2006 to shareholders of record on February 15, 2006. The Board also declared quarterly dividends on the corporation’s four series of preferred stock, payable March 1, 2006 to shareholders of record on February 15, 2006.

2006 Expectations

Otter Tail Corporation anticipates 2006 diluted earnings per share from continuing operations to be in a range from $1.60 to $1.80. Contributing to the earnings guidance for 2006 are the following items:

• The corporation expects solid performance in the electric segment in 2006 although net income is anticipated to be lower than 2005 levels. This is primarily because margins on wholesale electric sales are expected to be tighter as the MISO market becomes more efficient, anticipated increases in transmission service and wage and

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	benefit costs, and uncertainty related to the recoverability of certain MISO-related costs through the fuel clause adjustments in Minnesota and North Dakota retail rates. The corporation expects earnings for the electric segment in 2006 to return to more historical levels.
•	The corporation expects the plastics segment performance to return to more historical levels in 2006 following the 2005 record year.
•	The improving economy, continued enhancements in productivity and capacity utilization, expanded markets, expansion of production capacity with the opening of a new wind tower production facility in Fort Erie, Ontario, Canada, and continued availability of the Production Tax Credits are expected to result in increased net income in the corporation’s manufacturing segment in 2006.
•	The health services segment is expected to have moderate growth in net income in 2006.
•	The corporation expects its food ingredient processing business (IPH) to generate net income in the range of $2 million to $4 million for the year ending December 31, 2006.
•	The other business operations segment is expected to show improved results over 2005 due to an improving economy and an increase in its backlog of construction contracts. An increase in wind energy projects activity is expected to have a positive impact on the corporation’s electrical contracting business.
•	The corporation anticipates investing approximately $57 million in capital expenditures during 2006 in addition to funding future acquisitions.
•	The corporation’s outlook reflects the impact of Statement of Financial Accounting Standards No. 123(R), Share-Based Payment in 2006, which is anticipated to lower diluted earnings per share results by $0.015 in 2006. This standard requires that all share-based compensation awards be measured at fair value at the date of grant and expensed over their vesting or service periods. SFAS 123(R) is effective for the corporation beginning in January 2006.

Risk Factors and Forward-Looking Statements that Could Affect Future Results

The information in this release includes certain forward-looking information, including the 2006 outlook, made under the Safe Harbor provisions of the Private Securities Litigation Reform Act of 1995. Although the corporation believes its expectations are based on reasonable assumptions, actual results may differ materially from those expectations. The following factors, among others, could cause actual results for the corporation to differ materially from those discussed in the forward-looking statements:

• The corporation is subject to government regulations and actions that may have a negative impact on its business and results of operations.

• Weather conditions can adversely affect the corporation’s operations and revenues.

• Electric wholesale margins could be reduced as the MISO market becomes more efficient.

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• Electric wholesale trading margins could be reduced or eliminated by losses due to trading activities.

• The decision to disallow recovery of certain MISO-related costs through the fuel clause adjustment in Minnesota could be upheld or deferred by the Minnesota Public Utilities Commission upon rehearing, resulting in a negative impact on the corporation’s cash flows and net income.

• Federal and state environmental regulation could cause the corporation to incur substantial capital expenditures which could result in increased operating costs.

• The corporation’s plans to grow and diversify through acquisitions may not be successful and could result in poor financial performance.

• Competition is a factor in all of the corporation’s businesses.

• Economic uncertainty could have a negative impact on the corporation’s future revenues and earnings.

• Volatile financial markets could restrict the corporation’s ability to access capital and could increase borrowing costs and pension plan expenses.

• The corporation’s food ingredient processing segment operates in a highly competitive market and is dependent on adequate sources of raw materials for processing. Should the supply of these raw materials be affected by poor growing conditions, this could negatively impact the results of operations for this segment. This segment could also be impacted by foreign currency changes between Canadian and United States currency and prices of natural gas.

• The corporation’s plastics segment is highly dependent on a limited number of vendors for PVC resin. The loss of a key vendor or an interruption or delay in the supply of PVC resin could result in reduced sales or increased costs for this business.

• The corporation’s health services businesses may not be able to retain or comply with the dealership arrangement and other agreements with Philips Medical.

For a further discussion of other risk factors and cautionary statements, refer to reports the corporation files with the Securities and Exchange Commission.

About The Corporation

Otter Tail Corporation has interests in diversified operations that include an electric utility, plastics, manufacturing, health services, food ingredient processing and other businesses. Otter Tail Corporation stock trades on NASDAQ under the symbol OTTR. The latest investor and corporate information is available at www.ottertail.com. Corporate offices are located in Fergus Falls, Minnesota, and Fargo, North Dakota.

See Otter Tail Corporation’s results of operations for the three months and years ended December 31, 2005 and 2004 in the attached financial statements.

Consolidated Statements of Income, Consolidated Balance Sheets — Assets, Consolidated Balance Sheets — Liabilities and Equity

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Otter Tail Corporation
Consolidated Statements of Income
For the three and twelve months ended December 31, 2005 and 2004
In thousands, except share and per share amounts

	Quarter Ended December 31,						Year to date — December 31,
	2005			2004			2005			2004
Operating revenues by segment:
Electric	$	79,582		$	70,441		$	312,985		$	266,385
Plastics		44,927			28,780			158,548			115,426
Manufacturing		61,121			57,029			244,311			201,615
Health services		34,216			34,304			123,991			114,318
Food ingredient processing		11,204			9,220			38,501			14,023
Other business operations		55,059			40,652			171,939			148,328
Intersegment eliminations		(870	)		(823	)		(3,867	)		(2,733	)
Total operating revenues		285,239			239,603			1,046,408			857,362
Operating expenses:
Fuel and purchase power		29,807			23,012			114,755			92,154
Nonelectric cost of goods sold (excludes depreciation; included below)		155,775			131,361			566,647			464,009
Electric operating and maintenance expense		29,496			25,565			109,947			95,772
Nonelectric operating and maintenance expense		35,058			24,044			110,004			86,542
Goodwill impairment loss		—			—			1,003			—
Depreciation and amortization		11,800			11,553			46,458			43,471
Total operating expenses		261,936			215,535			948,814			781,948
Operating income (loss) by segment:
Electric		14,169			15,593			63,886			54,223
Plastics		9,788			2,826			23,853			10,285
Manufacturing		2,784			4,896			16,728			14,887
Health services		1,777			3,178			7,637			5,947
Food ingredient processing		(577	)		277			1,639			650
Other business operations		(4,638	)		(2,702	)		(16,149	)		(10,578	)
Total operating income — continuing operations		23,303			24,068			97,594			75,414
Interest charges		4,494			4,837			18,558			18,128
Other income		304			(87	)		1,786			793
Income taxes — continuing operations		6,355			5,247			27,967			17,447
Net income (loss) by segment — continuing operations:
Electric		8,468			10,222			37,301			31,535
Plastics		6,022			1,567			13,936			5,657
Manufacturing		1,211			2,598			7,589			7,563
Health services		925			1,741			4,007			2,951
Food ingredient processing		(904	)		142			329			351
Other business operations		(2,964	)		(2,373	)		(10,307	)		(7,425	)
Total net income — continuing operations		12,758			13,897			52,855			40,632
Discontinued operations
Income (loss) from discontinued operations net of taxes of ($124); $653; ($221) and $1,040 for the respective periods		(152	)		981			(308	)		1,563
Net gain on disposition of discontinued operations — net of taxes of $45 and $5,831 for the three and twelve months ended December 31, 2005		67			—			10,004			—
Net income from discontinued operations		(85	)		981			9,696			1,563
Total net income		12,673			14,878			62,551			42,195
Preferred stock dividend		183			184			735			736
Balance for common:	$	12,490		$	14,694		$	61,816		$	41,459
Average number of common shares outstanding—basic		29,360,609			26,662,711			29,222,621			26,089,361
Average number of common shares outstanding—diluted		29,555,101			26,779,759			29,347,710			26,206,567
Basic earnings per common share:
Continuing operations (net of preferred dividend requirement)	$	0.43		$	0.51		$	1.79		$	1.53
Discontinued operations	$	—		$	0.04		$	0.33		$	0.06
	$	0.43		$	0.55		$	2.12		$	1.59
Diluted earnings per common share:
Continuing operations (net of preferred dividend requirement)	$	0.42		$	0.51		$	1.78		$	1.52
Discontinued operations	$	—		$	0.04		$	0.33		$	0.06
	$	0.42		$	0.55		$	2.11		$	1.58

Otter Tail Corporation
Consolidated Balance Sheets
Assets
In thousands

	December 31,		December 31,
	2005		2004
Current assets
Cash and cash equivalents	$	5,430	$	—
Accounts receivable:
Trade—net		128,355		116,141
Other		11,790		9,872
Inventories		88,677		72,504
Deferred income taxes		6,871		4,852
Accrued utility revenues		22,892		15,344
Costs and estimated earnings in excess of billings		21,542		18,145
Other		17,301		7,800
Assets of discontinued operations		2,317		30,937
Total current assets		305,175		275,595
Investments and other assets		33,824		42,650
Goodwill—net		98,110		92,196
Other intangibles—net		21,160		19,600
Deferred debits:
Unamortized debt expense and reacquisition premiums		6,520		7,291
Regulatory assets and other deferred debits		19,616		16,692
Total deferred debits		26,136		23,983
Plant
Electric plant in service		910,766		890,200
Nonelectric operations		228,548		208,311
Total		1,139,314		1,098,511
Less accumulated depreciation and amortization		459,438		436,856
Plant—net of accumulated depreciation and amortization		679,876		661,655
Construction work in progress		17,215		18,469
Net plant		697,091		680,124
Total	$	1,181,496	$	1,134,148

Otter Tail Corporation
Consolidated Balance Sheets
Liabilities and Equity
In thousands

	December 31,			December 31,
	2005			2004
Current liabilities
Short-term debt	$	16,000		$	39,950
Current maturities of long-term debt		3,340			6,016
Accounts payable		106,570			84,433
Accrued salaries and wages		24,326			17,330
Accrued federal and state income taxes		8,776			3,700
Other accrued taxes		12,620			11,391
Other accrued liabilities		14,975			10,417
Liabilities of discontinued operations		372			8,585
Total current liabilities		186,979			181,822
Pensions benefit liability		23,216			16,703
Other postretirement benefits liability		26,982			25,053
Other noncurrent liabilities		18,683			11,874
Deferred credits
Deferred income taxes		113,737			121,301
Deferred investment tax credit		9,327			10,477
Regulatory liabilities		61,624			56,909
Other		1,500			1,662
Total deferred credits		186,188			190,349
Capitalization
Long-term debt, net of current maturities		258,260			261,805
Class B stock options of subsidiary		1,258			1,832
Cumulative preferred shares		15,500			15,500
Cumulative preference shares — authorized 1,000,000 shares without par value; outstanding — none		—			—
Common shares, par value $5 per share		147,006			144,885
Premium on common shares		96,768			87,865
Unearned compensation		(1,720	)		(2,577	)
Retained earnings		228,515			199,427
Accumulated other comprehensive loss		(6,139	)		(390	)
Total common equity		464,430			429,210
Total capitalization		739,448			708,347
Total	$	1,181,496		$	1,134,148