By Dan O\u2019Keefe Michigan State University Extension The United States Army Corps of Engineers (USACE) is now considering eight options identified in the Great Lakes Mississippi Interbasin Study (GLMRIS). Public comments are being accepted until March 3. Federal officials are holding several meetings across the region to discuss the options. A meeting was held on Tuesday in Ann Arbor, while another will be held today in Traverse City. As with any non-native species, there are many potential pathways for invasion. The Chicago Area Waterway System (CAWS) is one of these pathways. The canals of the CAWS were designed to flush sewage and stormwater runoff from Chicago down the Des Plaines and Illinois rivers of the Mississippi River basin. Doing this now requires the diversion of 2.1 billion gallons of Lake Michigan water each day. The city of Chicago grew up depending on canals for sanitation, flood control and navigation. The city\u2019s infrastructure was developed in relation to these canals, the first of which was constructed beginning in 1836. If you want to stop Asian carp and other aquatic nuisance species (ANS) from accessing the Great Lakes through Chicago area waterways, it is important to understand the GLMRIS options before commenting. In your comments, make sure to reference the specific option that you prefer. This will leave no room for doubt when interpreting public input at the end of the comment period. A brief overview of each Alternative Plan follows; more specifics are available in a 28-page summary \u2014 at glmris.anl.gov\/documents\/docs\/glmrisreport\/GLMRISSummaryReport.pdf \u2014 and the full GLMRIS report \u2014 at glmris.anl.gov\/glmris-report. \u00a0 Alternative Plan 1: No new federal action If you think that current efforts that include electric barriers and removal netting are sufficient, this is the option for you. There are costs associated with current actions, but this is the baseline condition to which other alternatives are compared. \u00a0 Alternative Plan 2: Nonstructural control technologies This plan involves additional netting, chemical control, watercraft inspection, and education efforts in multiple states but does not involve additional structures to separate waterways. The estimated additional cost is $68 million annually, and this option could be pursued in addition to other options. \u00a0 Alternative Plan 3: Control technologies without buffer zone This option involves $9.1 billion in flood mitigation and two structures dubbed \u201cGLMRIS Locks.\u201d The GLMRIS locks allow navigation to continue and do not achieve hydrologic separation. Instead, these locks would operate in conjunction with pumps and water treatment facilities to provide some measure of control specific to ANS that drift passively through the waterways. The price tag for these ANS control measures along with two additional electric barriers is $4 billion and the estimated additional cost of this alternative is $15.5 billion. \u00a0 Alternative Plan 4: Control technology with buffer zone This option involves GLMRIS locks and electric barriers at three locations different from those proposed in Alternative 3. Flood mitigation costs (~$2 billion) are less than Plan 3 and the estimated additional cost is $7.8 billion. \u00a0 Alternative Plan 5: Lakefront hydrologic separation Four physical barriers located in canals near Lake Michigan are used to restore the natural divide in this plan. Water from Lake Michigan would be treated in ANS treatment plants before being released in CAWS canals to flush Chicago area runoff and Combined Sewer Overflow effluent downstream. This option includes $14.4 billion in flood mitigation because runoff from heavy rains would no longer be drained into Lake Michigan. The cost of barriers and other ANS controls is $446 million and the total additional cost estimate is $18.4 billion. \u00a0 Alternative Plan 6: Mid-system hydrologic separation Physical barriers placed near the midpoint of two canals achieve basin separation in this plan, which also incorporates ANS treatment plants and conveyance tunnels to use Lake Michigan for maintenance of water quality in the CAWS. The cost of barriers is $223 million, while the cost of water quality mitigation is over $12.8 billion. Total estimated additional cost is $15.2 billion. \u00a0 Alternative Plan 7: Calumet-Sag Channel Open Control \u201chybrid\u201d This plan places a physical barrier on the Chicago Sanitary and Ship Canal but leaves the Cal-Sag open for navigation between basins via GLMRIS lock. Total estimated additional cost is $15.1 billion. \u00a0 Alternative Plan 8: Chicago Sanitary and Ship Canal Open Control \u201chybrid\u201d This option is the reverse of Plan 7, leaving the Chicago Sanitary and Ship Canal open to navigation and without hydrologic separation. Total estimated additional cost is $8.3 billion. \u00a0 Hydrologic separation of CAWS is the surest way to eliminate this pathway for Asian carp and other invaders. No, it won\u2019t solve all of the problems associated with other pathways such as illegal stocking, but in the world of invasive species control it is essential to focus on pathways for invasion instead of individual species. One reason for this is that we never know what the next invader will be. If the pathway is closed, we are not left scraping for new species-specific control technologies when a new invader shows up. One downside of hydrologic separation is that it would require major infrastructure changes to mitigate flooding and water quality impacts that would impact the lives of many people. Fortunately, the GLMRIS gives approximate costs that include mitigation. The study does not indicate a preferred option, nor does it state who will cover the costs associated with each option. Those are decisions that are now a matter for public debate. Now that design options and cost estimates are officially on the table, Great Lakes advocates, industry representatives and taxpayers can take the time to register an informed opinion. If you decide to comment \u2013 by visiting glmris.anl.gov\/glmris-report\/comments \u2013 be sure to reference the Alternative Plan you prefer; even if you do go on to voice concerns about certain design aspects, costs, or funding sources for implementation. For additional information on Asian carp, search previous Michigan State University Extension news articles on hydrologic separation, emerging science and control options.