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                                    HACH COMPANY
                            EMPLOYEE STOCK PURCHASE PLAN
                   AS AMENDED AND RESTATED AS OF JANUARY 1, 1998
                                          
     The purpose of this Plan is to provide employees a continued opportunity 
to purchase shares of Hach Class A Common Stock through semi-annual offerings 
to be made during the five-year period commencing July 1, 1995.  As of 
January 1, 1998, five hundred thousand (500,000) shares of Class A Common 
Stock in the aggregate have been approved for this purpose.  The shares of 
Class A Common Stock to be sold to participants under this Plan may be 
treasury shares, authorized and unissued shares or Plan Purchase shares as 
provided in Section 20 below.

     1.   ADMINISTRATION. The Plan shall be administered by a Committee 
appointed by the Board of Directors from its members or members of senior 
management, consisting of at least three members. Members of the Committee 
shall not be eligible to participate in the Plan.

     2.   ELIGIBILITY.  Except as provided below, all employees of the 
Corporation or its domestic subsidiaries who shall have been employed for a 
period of 180 days preceding an offering period and whose customary 
employment exceeds twenty (20) hours per week shall be eligible to 
participate in the Plan in accordance with such rules as may be prescribed by 
the Committee from time to time, which rules, however, shall neither permit 
nor deny participation in the Plan contrary to the requirements of the 
Internal Revenue Code (including, but not limited to, Section 423(b)(3), (4), 
(5) and (8) thereof) and the regulations promulgated thereunder. No employee 
may be granted an option if such employee, immediately after the option is 
granted, owns 5% or more of the total combined voting power or value of the 
stock of the Corporation or any subsidiary. For purposes of the preceding 
sentence, the rules of Section 424(d) of the Internal Revenue Code shall 
apply in determining the stock ownership of an employee, and stock that the 
employee may purchase under outstanding options shall be treated as stock 
owned by the employee.

     3.   OFFERINGS.  The Corporation shall make one or more six-month 
offerings to employees to purchase Class A Common Stock under this Plan. Each 
offering period shall be six months in duration, commencing on January 1 and 
July 1 of each year. During such offering periods (or during such portion 
thereof as an employee may elect to participate) the amounts received as 
compensation by an employee shall constitute the measure of such of the 
employee's participation in the offering as is based on compensation.

     4.   PARTICIPATION.  An employee eligible on the effective date of any 
offering may participate in such offering at any time by completing and 
forwarding a payroll deduction authorization to the employee's appropriate 
payroll location. The form will authorize a regular payroll deduction from 
the employee's compensation, and must specify the date on which such 
deduction is to commence, which may not be retroactive. Such authorization 
shall be applicable to subsequent offering periods unless the employer 
increases or decreases the employee's payroll deduction as provided in 
Section 6 or withdraws from participation as provided in Section 7 below.

                                    

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     5.   DEDUCTIONS.  The Corporation shall maintain payroll deduction 
accounts for all participating employees. With respect to any offering made 
under this Plan, an employee may authorize a payroll deduction of a whole 
percentage (up to a maximum of 10 %) of the compensation the employee 
receives during the offering period (or during such portion thereof in which 
the employee may elect to participate).

     No employee may be granted an option that permits his or her rights to 
purchase stock under this Plan, and any other stock purchase plan of the 
Corporation and its subsidiaries, to accrue at a rate that exceeds $25,000 of 
the fair market value of such stock (determined at the effective date of the 
applicable offering) for each calendar year in which the option is 
outstanding at any time.
     
     6.   DEDUCTION CHANGES.  An employee may increase or decrease the 
employee's payroll deduction by filing a new payroll deduction authorization 
at any time. The change may not become effective sooner than the next 
offering period after receipt of the authorization.

     7.   WITHDRAWAL.  
          
          (a)  A participating employee may withdraw payroll deductions 
credited to such employee's account under the Plan at any time by giving 
written notice to a designated representative of the Corporation no later 
than 7 days prior to the last day of any offering period. All of the payroll 
deductions credited to the employee's account will be paid to the employee 
promptly after receipt of such notice of withdrawal, and no further 
deductions will be made from such employee's pay during that Offering Period.

          (b)  An employee's withdrawal will not have any effect upon such 
employee's eligibility to participate in any similar plan which may hereafter 
be adopted by the Corporation or in any subsequent Offering Period under this 
Plan.
     
     8.   PURCHASE OF SHARES.  Each employee participating in any offering 
under this Plan shall be granted an option, upon the effective date of such 
offering, for as many full and fractional shares of Class A Common Stock as 
the participating employee may elect to purchase with up to 10% of the 
compensation received during the specified offering period (or during such 
portion thereof as the employee may elect to participate), to be paid by 
payroll deductions during such period.
     
          Notwithstanding the foregoing, in no event shall the number of 
shares purchased by an employee during an offering period exceed 2,000 shares.

          The purchase price for each share purchased shall be the lower of 
85% of the fair market price of a share of Class A Common Stock on the 
commencement date of the offering period or 85% of the fair market price of a 
share of Class A Common Stock on the last day of the offering period. As of 
the last day of any offering period, the account of each participating 
employee shall be totaled, and the employee shall be deemed to have exercised 
an option to purchase one or more full or fractional shares at the 
then-applicable price; the employee's account shall be charged for the amount 
of the purchase; and the ownership of such share or shares shall 

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be appropriately evidenced on the books of the Corporation. Additional shares 
covered by the employee's option shall be purchased in the same manner, as of 
the last day of each subsequent offering period. A participating employee may 
not purchase a share under any offering period beyond 6 months from the 
effective date thereof. Any balance remaining in an employee's payroll 
deduction account at the end of an offering period will be carried forward to 
the next offering period.

     9.   EMPLOYEE ACCOUNTS AND CERTIFICATES.  Upon purchase of one or more 
full or fractional shares by a Plan participant pursuant to Section 8 hereof, 
the Corporation shall establish a book entry account in the name of the 
employee to reflect the share(s) purchased at that time. Certificates shall 
be issued only on request for full shares. In the event a participant 
terminates his or her account, any fractional share held in the account will 
be paid to the participant in cash.

     10.  REGISTRATION OF SHARES.  Shares may be registered only in the name 
of the employee, or, if the employee so indicates on the employee's payroll 
deduction authorization form, in the employee's name jointly with a member of 
the employee's family, with right of survivorship. An employee who is a 
resident of a jurisdiction that does not recognize such a joint tenancy may 
have shares registered in the employee's name as tenant in common or as 
community property with a member of the employee's family, without right of 
survivorship.

     11.  DEFINITIONS.
     
          (a)  The term "Corporation" or "Hach" means Hach Company, a 
Delaware corporation.

          (b)  The term "Class A Common Stock" means Class A Common Stock, 
par value $1.00 per share, of Hach.

          (c)  The phrase "fair market price" per share on any given date 
shall mean (i) the closing price of Class A Common Stock as reported on the 
NASDAQ National Market System or, (ii) if on any such date Class A Common 
Stock is not reported on such System, the average of the closing bid and 
asked prices with respect to Class A Common Stock as furnished by a 
professional market maker making a market in Class A Common Stock selected by 
the Board of Directors, or (iii) if no such closing price or average of the 
closing bid and asked prices are available, such closing price or if not 
available, such average of the closing bid and asked prices on the next 
preceding business day on which such price or prices were reported, or (iv) 
if no such price or prices are available, the fair market value of the Class 
A Common Stock as of such date as determined in good faith by the Board of 
Directors.

          (d)  The term "subsidiary" means a subsidiary of the Corporation 
within the meaning of Section 424(f) of the Internal Revenue Code and the 
regulations promulgated thereunder.
     
     12.  RIGHTS AS A STOCKHOLDER.  None of the rights or privileges of a 
stockholder of the Corporation shall exist with respect to shares purchased 
under this Plan unless and until such shares shall have been appropriately 
evidenced on the books of the Corporation.


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     13.  RIGHTS ON RETIREMENT. DEATH OR TERMINATION OF EMPLOYMENT.  In the 
event of a participating employee's retirement, death, or termination of 
employment, the employee shall be ineligible to continue to participate in 
the Plan, and no payroll deduction shall be taken from any pay due and owing 
to the employee after the pay period during which the employee became 
ineligible.

     14.  RIGHTS NOT TRANSFERABLE.  Rights under this Plan are not 
transferable by a participating employee other than by will or the laws of 
descent and distribution, and are exercisable during the employee's lifetime 
only by the employee.

     15.  APPLICATION OF FUNDS AND ADMINISTRATIVE FEES.  All funds received 
or held by the Corporation under this Plan may be used for any corporate 
purpose. The Committee may impose reasonable administrative fees on 
participating employees to defray the administrative costs of the Plan, which 
shall in no event exceed the actual administrative costs of the Plan. 
Initially, the fee shall be $10 per participating employee. An employee who 
withdraws from participation shall pay an additional administration fee 
should such employee elect to again participate in a subsequent offering 
under this Plan.

     16.  ADJUSTMENTS IN CASE OF CHANGES AFFECTING CLASS A COMMON STOCK.  In 
the event of a subdivision of outstanding shares, or the payment of a stock 
dividend, the number of shares approved for this Plan, and the share 
limitation set forth in Section 8 hereof, shall be increased proportionately, 
and such other adjustments shall be made as may be deemed equitable by the 
Board of Directors. In the event of any other change affecting Class A Common 
Stock, such adjustments shall be made as may be deemed equitable by the Board 
of Directors to give proper effect to such event.

     17.  AMENDMENT OF THE PLAN.  The Board of Directors may at any time, or 
from time to time, amend this Plan in any respect, except that, without the 
approval of a majority of the shares of stock of the Corporation then issued 
and outstanding and entitled to vote, no amendment shall be made (i) 
increasing the number of shares approved for this Plan (other than as 
provided in Section 16 hereof), (ii) decreasing the purchase price per share, 
(iii) withdrawing the administration of this Plan from a Committee consisting 
of persons not eligible to participate in the Plan, or (iv) changing the 
designation of subsidiaries eligible to participate in the Plan.

     18.  TERMINATION OF THE PLAN.  This Plan and all rights of employees 
under any offering hereunder shall terminate:
     
          (a)  On the day that participating employees become entitled to 
purchase a number of shares equal to or greater than the number of shares 
remaining available for purchase. If the number of shares so purchasable is 
greater than the shares remaining available, the available shares shall be 
allocated by the Committee among such participating employees in such manner 
as it deems fair; or

          (b)  At any time, at the discretion of the Board of Directors.

     No offering hereunder shall be made which shall extend beyond June 30, 
2000.

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     19.  GOVERNMENTAL REGULATIONS.  The Corporation's obligation to sell and 
deliver Class A Common Stock under this Plan is subject the approval of any 
governmental authority required in connection with the authorization, 
issuance, or sale of such stock.

     20.  PLAN SHARES PURCHASES.  Purchases of outstanding shares may be made 
pursuant to and on behalf of this Plan, upon such terms as the Corporation 
may approve, for delivery under this Plan.


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