The department of natural resources and the department of agriculture and land stewardship shall have the power and authority reasonably necessary to carry out the duties imposed by this chapter. As to the department of natural resources, this includes rulemaking authority to carry out the regional watershed assessment program described in section 466B.5. As to the department of agriculture and land stewardship, this includes rulemaking authority to assist in the implementation of community-based subwatershed improvement plans.