摘要: A programmatic Environmental Impact Statement (EIS) was prepared to assess the environmental impacts to the Upper Mississippi River System (UMRS) from the major rehabilitation effort. The majority of the rehabilitation work has co... 展开 A programmatic Environmental Impact Statement (EIS) was prepared to assess the environmental impacts to the Upper Mississippi River System (UMRS) from the major rehabilitation effort. The majority of the rehabilitation work has consisted of repair and replacement items. However, certain measures were identified as having the potential to increase navigation traffic and possibly cause cumulative impacts to the UMRS. A traffic analysis was conducted to determine whether operation of the measures would be likely to increase commercial navigation on the UMRS. The traffic analysis concluded that during the navigation season a very small increase in system traffic may occur with the proposed measures in place. This small increase is within the normal variability of any navigation season and would not result in system wide (cumulative) impacts to the UMRS that are measurable over the existing condition. Although projected traffic increases are minor, concern has been expressed that traffic increases may be concentrated at the end of the navigation season, due to the installation high-volume bubbler systems. End-season traffic is highly variable and unpredictable, with no typical time period or volume of traffic associated with it. Ice conditions in the river channel are the controlling factor. Industry representatives have indicated that bubbler systems would not induce further traffic, but only assist in the orderly withdrawal of tows. The installation of high-volume bubbler systems would not promote a higher level of end-season traffic. (SDW) 收起