HACH CO

Certification of termination of registration of a class of securities (Section 12(g))

5

5,7

General form for quarterly reports under Section 13 or 15(d)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

General form for quarterly reports under Section 13 or 15(d)

General form for quarterly reports under Section 13 or 15(d)

Definitive Proxy Statement

Annual report pursuant to Section 13 or 15(d)

1

Prospectus Supplement for Primary Offering

Registration statement under Securities Act of 1933

General form for quarterly reports under Section 13 or 15(d)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

General form for quarterly reports under Section 13 or 15(d)

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

General form for quarterly reports under Section 13 or 15(d)

No description available

Withdrawal of a registration statement

Registration of Securities on Exchange

Definitive Proxy Statement

Annual report pursuant to Section 13 or 15(d)

Preliminary Proxy Statement

Beneficial ownership report for a holder of more than 5% (Schedule 13D)

7

Beneficial ownership report for a holder of more than 5% (Schedule 13D)

No description available

No description available

General form for quarterly reports under Section 13 or 15(d)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

General form for quarterly reports under Section 13 or 15(d)

General form for quarterly reports under Section 13 or 15(d)

No description available

Definitive Proxy Statement

Preliminary Proxy Statement

General form for quarterly reports under Section 13 or 15(d)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

General form for quarterly reports under Section 13 or 15(d)

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

5,7

5,7

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

General form for quarterly reports under Section 13 or 15(d)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

No description available

Definitive Proxy Statement

General form for quarterly reports under Section 13 or 15(d) (amendment)

General form for quarterly reports under Section 13 or 15(d)