A district may regulate and control the construction, maintenance, and operation, or use, of all wharves, warehouses, structures, improvements, or appliances used in connection with or for the accommodation and promotion of transportation or navigation on any improvement project of the federal government applying to the main waterway entering the district and also on other navigable streams improved or unimproved which lie within the district, and make and enforce necessary police and sanitary regulations in connection therewith.