To the extent that funds are made available by the legislature, the state shall assume 90 percent of the nonfederal costs of planning, land acquisition, construction, and maintenance of flood control projects authorized within the state by the United States, except that the state shall assume the full share of nonfederally funded costs with respect to those facilities that are primarily state responsibilities, including highways and roads, parks and recreation, and fish and game facilities. The state shall participate in federal flood control projects under this section only as to those projects authorized and approved by the department.