Subject: Westminster, East Garden Grove, California flood risk management

DEPARTMENT OF THE ARMY CHIEF OF ENGINEERS 2600 ARMY PENTAGON WASHINGTON, DC 20310-2600 DAEN SUBJECT: Westminster, East Garden Grove, California Flood Risk Management THE SECRETARY OF THE ARMY 1. I submit, for transmission to Congress, my report on flood risk management in the Westminster watershed in Orange County, California to reduce the occurrence of flood flows overtopping existing drainage channel systems during storm events. It is accompanied by the report of the District Commander. The report is an interim response to the resolution adopted by the House of Representatives Committee on Public Works on May 8, 1964 which requested that the U.S. Army Corps of Engineers (USACE) review "the reports on (a) San Gabriel River and Tributaries, published as House Document No. 838, 76th Congress, 3d Session; (b) Santa Ana River and Tributaries, published as House Document No. 135, 81 st Congress, 1st Session; and (c) the project authorized by the Flood Control Act of 1936 for the protection of the metropolitan area in Orange County, with a view to determining the advisability of modification of the authorized projects in the interest of flood control and related purposes." Funds from the Bipartisan Budget Act of 2018, Public Law 115-123, were used to complete the study. Preconstruction, engineering, and design activities, if funded, will continue under the study authority cited above. 2. The reporting officers recommend authorizing a Locally Preferred Plan to reduce flood risks to the communities located within the Westminster watershed in Orange County, California. The principal features of the plan include: a. Modification of approximately 25 miles of existing drainage channels to increase storage capacity and improve conveyance efficiency. This Locally Preferred Plan is designed to contain the one-percent annual exceedance probability (AEP) storm event. For the C02/C04 channel system, the plan includes conversion of approximately 11 ,600 linear feet of trapezoidal cha