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SECTION 22 - COLORADO PLAllNING ASSISTANC]~ 'ro STATES SOUTH PLATTI': RIVER MERINO, COl:,ORADO May l!ll!I3 INTRODUCTION The study area is located along a half'-mile reach of the South Platte River in Logan County, Color,:ido, approximately 1.5 miles south of Merino, as shown on Plate 1. The objective of 1:his study is to present reconnaissance-level alternatives to remove the sandbar and island tha.t have formed under the center of the bridge. AUTHORITY This study was conducted for the Logan County Board of Commissioners (the sponsor) under the Corps of Engineers' Planning Assistance to States (PAS) program, a program authorized by Section 22 of the Water Resources Development Act: of 1974, as amended. The fiscal year 1992 study was cost-sharE~d 70-30 between the Corps of Engineers and the sponsor. SITE AND PROBLEM DESCRIPTION The South Platte River is a meandering river that historically has moved across the flood plain with major channel avulsions coinciding with major flood events. Since t:he turn of the century, extensive agricultural development of the flood plain has included numerous irrigation diversions. ..z\.lso, upstream flood control projects and municipal/industrial dev,elopment have furthE!r altered the flow regime of the South platt,;, River through Logan County. The river is now a braided bed-load stream characterized by large vegetated islands, emergent sandbars, and anabranching. Anabranching is the formation of lonq side channels that tend to maintain themselves for long periods of time and may eventually become the main channel. The rest:l.l t of anabranching is large, relatively high-elevation islands. Over the past several years, a sandbar and island have, formed immediately upstream from the bridge south of Merino. This sandbar effectively plugs 50 percent of the Section 22 - South Platte River, Merino, Colorado