A watershed improvement district organized under the provisions of this article shall constitute a governmental division of this state and a public body corporate, and such watershed improvement district shall have all of the powers of the soil conservation district or districts in which the watershed improvement district is situated. These powers are set forth in article twenty-one-a, chapter nineteen of the code, and any reference therein to a "soil conservation district" shall be deemed for the purposes of this article to include a "watershed improvement district." The trustees shall exercise only such of the powers of the watershed improvement district as the governing body of the district may designate from time to time.