<PAGE>
                                                                    Exhibit 10-A

                             OTTER TAIL CORPORATION
                         EXECUTIVE EMPLOYMENT AGREEMENT
                                  JOHN ERICKSON

     This Executive Employment Agreement (the "Agreement") is entered into as of
this 15th day of February, 2002, by and between Otter Tail Corporation, a
Minnesota corporation (the "Corporation") and John Erickson ("You"). The
Corporation agrees to employ You and You agree to be employed consistent with
the terms of this Agreement as follows:

     1. Employment. The Corporation agrees to employ You and You agree to be
employed as President consistent with the terms and conditions set forth in this
Agreement.

     2. Duties. You shall have such duties as are assigned or delegated to You
by the Corporation's Board of Directors or its designee. Except as provided for
in Section 7 of this Agreement or subsequently agreed upon by You and the
Corporation, You agree to devote Your entire business time, attention, skill,
and energy exclusively to the business of the Corporation, to use Your best
efforts to promote the success of the Corporation's business, and to cooperate
fully with the Board of Directors in the advancement of the best interests of
the Corporation.

     3. Compensation and Benefits.


          a.   Base Pay. You shall be paid an annual salary ("Base Pay") of
               $272,000, which shall be payable in equal periodic installments
               according to the Corporation's customary payroll practices, but
               no less frequently than monthly, and subject to such withholdings
               and deductions as required by law. Your Base Pay shall be
               reviewed in April of each year by the Board of Directors, and any
               change in Base Pay approved by the Board shall become effective
               April 1 of the year in which it is approved.

          b.   Incentive Compensation. You shall be paid an annual incentive
               payment based on the Corporation's Management Incentive Plan, or
               its successor plan, as approved by the Corporation's Board of
               Directors, and based on the rules of the plan. Your incentive
               payment shall be paid to You as soon as administratively possible
               upon approval of the Corporation's financial results after the
               close of each calendar year.

          c.   Benefits. In addition to the compensation described above and
               subject to rules of eligibility, You shall be permitted to
               participate in the benefit plans and long-term incentive plans
               available to full time executive level employees of the
               Corporation as they now exist and may from time to time be
               modified or established by the Corporation. The plan documents
               shall govern Your participation in any benefit plan.

     4. Expenses. The Corporation shall pay Your dues in such professional
societies and organizations as are appropriate for Your position, and shall pay
on Your behalf (or reimburse You for) reasonable expenses incurred by You on
behalf of the Corporation in the performance of the Your duties pursuant to this
Agreement, including reasonable expenses



<PAGE>

incurred by You in attending conventions, seminars, and other business meetings,
in appropriate business entertainment activities, and for promotional expenses.
You shall file such expense reports as are required by the Corporation's
policies and federal income tax laws and regulations.

     5. Confidentiality of Information.


          a.   You acknowledge that the Corporation possesses and will continue
               to develop and acquire valuable Confidential Information (as
               defined below), including information that You may develop or
               discover as a result of your employment with the Corporation. The
               value of that Confidential Information depends on it remaining
               confidential. The Corporation depends on You to maintain the
               confidentiality, and You accept that position of trust.

          b.   As used in this Agreement, "Confidential Information" means any
               information (including any formula, pattern, compilation,
               program, device, method, technique or process) that derives
               independent economic value, actual or potential, from not being
               generally known to the public or to other persons who can obtain
               economic value from its disclosure or use and includes
               information of the Corporation, its customers, suppliers, joint
               ventures, licensors, distributors and other persons and entities
               with whom the Corporation does business.

          c.   You shall not disclose or use at any time, either during or after
               your employment with the Corporation, any Confidential
               Information except for the exclusive benefit of the Corporation
               as required by your duties or as the Corporation expressly may
               consent to in writing. You shall cooperate with the Corporation
               to implement reasonable measures to maintain the secrecy of, and
               use your best efforts to prevent the unauthorized disclosure, use
               or reproduction of all Confidential Information.

          d.   Upon leaving employment with the Corporation for any reason, You
               shall deliver to the Corporation all tangible, written,
               graphical, machine readable and other materials (including all
               copies) in your possession or under your control containing or
               disclosing Confidential Information.

     6. Termination/Severance. Either party may terminate the employment
relationship as evidenced by this Agreement at any time and for any reason upon
ninety days written notice to the other.

          a.   If You elect to terminate the employment relationship, or if You
               are terminated by the Company for Cause, You shall receive Base
               Pay and benefits through the date of termination. Cause means
               your termination of employment with the Corporation based upon
               embezzlement or other intentional misconduct which is materially
               injurious to the Corporation, monetarily or otherwise.

          b.   If the Corporation elects to terminate the employment
               relationship or if You elect to resign for Good Reason, You shall
               receive a severance payment equal


                                       2
<PAGE>

               to one and one-half (1-1/2) times the sum of your present Base
               Pay plus your most recent annual incentive payment (the
               "Severance Payment"), in full satisfaction of the Corporation's
               obligations to You as an employee. The Severance Payment will be
               paid within fifteen (15) days of the date of termination and
               shall be subject to payroll taxes and any withholding
               obligations. Good Reason means the occurrence of any of the
               following events:

               (1)  a material change in your responsibilities or title which
                    are not of comparable responsibility and status as those
                    held upon execution of this Agreement;

               (2)  a reduction in your Base Pay, or a modification of the
                    Corporation's incentive compensation program or benefits in
                    a manner materially adverse to You;

               (3)  a breach or alteration of any material term of this contract
                    without your consent.

          c.   If You are terminated in connection with a Change in Control, as
               defined by the Change in Control Severance Agreement entered into
               by You and the Corporation (the "Severance Agreement"), and You
               receive payment of the severance benefits under Section 4 of the
               Severance Agreement, no Severance Payment shall be due to You
               under this Agreement.

     7. Special Considerations. None.


     8. Entire Agreement. This Agreement and the Change in Control Severance
Agreement represent the entire agreement between You and the Corporation
concerning the employment relationship of the parties commencing on February 15,
2002 and following and, thus, supersedes any and all previous written or oral
employment agreements or understandings concerning such matter.

     9. Disputes. Disputes under this Agreement shall be determined by
arbitration consistent with rules of the American Arbitration Association. The
costs of Arbitration shall be borne equally between You and the Corporation and
You shall bear your own attorney fees; provided, however, if You are the
prevailing party in Arbitration, all costs and attorney fees shall be paid by
the Corporation.

     10. Amendment/Governing Law. This Agreement may only be modified or amended
by a writing signed by both parties. This Agreement is made in and shall be
governed by the substantive laws of the State of Minnesota.



                                       3
<PAGE>


FOR THE CORPORATION:



      /s/ George A. Koeck                   2/15/02
-------------------------                   -----------------------------
                                            Date



ACKNOWLEDGED AND ACCEPTED BY:



      /s/ John Erickson                     2-15-02
 --------------------------                 ------------------------------
                                            Date



                                       4