Water Resources Development Act of 1986  The Water Resources Development Act of 1986 (WRDA 1986) is part of , a series of acts enacted by Congress of the United States on November 17, 1986. WRDA 1986 established cost sharing formulas for the construction of harbors, inland waterway transportation, and flood control projects and established rules therefor. It also created hundreds of projects, studies, and plans in almost every state in the nation. It also deauthorized a number of projects. WRDA 1986 directed the Secretary of the Army to issue guidelines for crediting against the non-Federal share of project cost for flood control any compatible work carried out by local interests. It authorized appropriations for the prosecution of the comprehensive plan of development for specified river basins and projects. It also prohibited the Government from initiating any feasibility study for a water resources project until non-Federal interests agree to contribute 50 percent of the costs during the period of the study but exempted from such prohibition any study designed for purposes of navigational improvements. It also prohibited the Government from initiating any planning or engineering authorized by this Act until non-Federal interests agree to contribute 50 percent of the costs during the period of planning and engineering. Finally, WRDA 1986 provided for determining the interest rate when a non-Federal interest elects to repay an amount under this Act over a period of time. Ultimately, WRDA 1986 authorized 262 water projects at a total cost of $16 billion. Authorized the Secretary to carry out 35 works of improvement for water resources development and conservation in Alabama, Mississippi, Alaska, Arkansas, California, Florida, Georgia, South Carolina, Iowa, Kentucky, Louisiana, Mississippi, Missouri, Illinois, Kansas, Nebraska, New York, North Carolina, Oklahoma, Oregon, Rhode Island, South Dakota, Tennessee, Texas, Virginia, Washington, West Virginia. Authorized construction of the following projects subject to favorable reports by the Chief of Engineers: (1) Rillito River, Tucson, Arizona; (2) Wailua Falls, Wailua River, Kauai, Hawaii; (3) Yazoo River, Mississippi; and (4) Trinity River, Texas. Authorized planning, engineering, and design for the following projects: (1) Neponset River, Milton Town Landing to Port Norfolk, Massachusetts; (2) Merrimack River, Massachusetts; (3) Buffalo Harbor, New York; (5) Wheeling Creek Watershed, Ohio; (5) Five Mile Creek, Dallas, Texas; and (6) Fox River Channel, Green Bay, Wisconsin.