Such flood control districts may be organized or maintained for any, or all, the following general purposes:

(1) The investigation, planning, construction, improvement, replacement, repair or acquisition of dams, dikes, levees, ditches, channels, canals, banks, revetments and other works, appliances, machinery and equipment and property and rights connected therewith or incidental thereto, convenient and necessary to control floods and lessen their danger and damages.

(2) The cooperation with any agency or agencies of the United States and/or of the state of Washington in investigating and controlling floods and in lessening flood dangers and damages.