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According to local officials, floating debris and ice have not been a conc em at this site. Roadway overflow has not been observed at this site. At the regional flood discharge of 1,200 cfs, a low flow condition exists that results in a highwater elevation of 895.46. The waterway opening is approximately 247 square feet, resulting in a velocity of 4.9 feet per second through the opening. The existing structure's navigational and design regional flood clearances are 6.7 feet and -0.4 feet, respectively. The existing horizontal roadway alignment is straight at the existing bridge. The vertical profile consists of a relatively flat grade. DISCUSSION OF STRUCTURE SIZING Adjacent land within the Maunesha River floodplain is primarily agricultural. The adjacent land use is primarily agricultural and wooded. There are no known buildings within the floodplain that would be affected by an increased highwater elevation. A copy of the letter with the Wisconsin Department of Natural Resources (WDNR) comments is attached for reference, and is summarized as follows. According to WDNR, Eric Heggelund, there are wetlands located in all quadrants of the existing bridge. Unavoidable impacts must be mitigated in accordance with the DOT/DNR Cooperative Agreement and the WisDOT Wetland Mitigation Banking Technical Guideline. According to WDNR, no known Endangered Resources or suitable habitats are known or likely to occur in the area (per check of National Heritage Inventory, etc. on February 3, 2014) The Manuesha River is a warm water fishery. In order to protect developing fish eggs and substrate for aquatic organisms, all instream work that could adversely impact water quality should be undertaken between May 15 and September 15. There may be migratory bird nesting on the existing structure. If nesting is verified, utilize measures to prevent nesting (placement of netting and removal of unoccupied nests, prior to May 1). If swallow nests are present under the existi ng structure, project should occur between August 30 and May 1, during non-nesting season. If used in the water, all equipment should be cleaned and dis infected to address the spread of invasive species and viruses. Follow STSP 107-055 Environmental Protection —Aquatic Exotic Species Control protocol. This reach of the Maunesha River is not regularly used by recreational watercraft. Navagational aids during const ruction are not necessary. Proper erosion control and waste disposal measures shall be used and maintained both during and after construction. 3 u:\41-0668.00-dane county,town bristol,elder lane\reports\bsr\b-13-672_siz.doc 41-0668.00