Dilly Twig Creek Basin Drainage Plan

Client—Lewis County Flood Control District 1, Washington

The Dilly Twig Basin is a sub-basin of the larger Dillenbaugh Basin, and runoff from upland area tributaries feed the Dilly Twig Creek. The channel capacity is often exceeded during more frequent and small magnitude storm events. A Drainage Plan was prepared and included; an inventory of existing infrastructure; evaluating the hydraulic capacity of the existing drainage network; recommending maintenance work; recommending a regional detention and treatment facility and associated conveyance system; and preparing a capital improvement plan for implementing improvements. Upon receipt of comments from the district on the preliminary plan, a final Regional Stormwater Management Plan was prepared for the District.