GLMRIS: Great Lakes and Mississippi River Interbasin Study

GLMRIS Frequently Asked Questions (FAQ)


What is GLMRIS?

Through Section 3061(d) of the Water Resources Development Act of 2007, Congress directed the Secretary of the Army, acting through the Chief of Engineers, to conduct a study evaluating a range of options and technologies available to prevent the transfer of aquatic nuisance species (ANS) between the Great Lakes and Mississippi River basins via aquatic pathways.

The U.S. Army Corps of Engineers (USACE) is conducting the study in consultation with other federal agencies, Native American tribes, state agencies, local governments and nongovernmental organizations.

The Chicago Area Waterway System is Focus Area 1 of GLMRIS, as it is the primary, continuous aquatic connection between the Mississippi River basin and the Great Lakes. Focus Area 2 is comprised of 18 pathways that have potential to become inter-basin transfer sites during flood events.

Why is GLMRIS important?

As a result of international commerce, travel and local practices, ANS have been introduced and have spread throughout the Great Lakes and Mississippi River basins. ANS threaten the diversity and abundance of native species; threaten the ecological stability of infested waters; or threaten the commercial, agricultural or recreational activities dependent on such waters.

What activities have been completed in GLMRIS?

  • Inventory of current conditions (economic, environmental and social) and forecast future conditions within the study area;
  • Identification of aquatic pathways that may exist between the Great Lakes and Mississippi River basins;
  • Inventory of current and future potential ANS;
  • Evaluation of possible ANS controls to prevent ANS transfer, to include hydrologic separation of the basins;
  • Analysis of impacts each ANS control may have on significant natural resources and existing and forecasted uses of the lakes and waterways within the study area;
  • Development of a report to provide Congress and other stakeholders with an analysis of potential ANS controls.

What is the GLMRIS Report?

The GLMRIS Report presents a range of options and technologies available to prevent the spread of ANS between the Great Lakes and Mississippi River basins through aquatic pathways. The report identifies eight alternative plans and evaluates the potential of these alternatives to control the inter-basin spread of 13 aquatic nuisance fish, algae, virus, crustaceans and plants in all life stages between the Great Lakes and Mississippi River basins. The options concentrate on the Chicago Area Waterway System (CAWS) and include a wide spectrum of alternatives ranging from the continuation of current activities to the complete separation of the watersheds. Each plan includes a general location, conceptual designs, estimated implementation time and cost information.

The report is a product of the Congressional study authorization. Congress asked USACE to evaluate a range of options and technologies available to prevent the spread of ANS transfer between the Great Lakes and Mississippi River basins via aquatic pathways. The report outlines potential prevention methods and evaluation criteria.

The CAWS is the main subject of the GLMRIS Report. In cooperation with state and local partners, additional progress has been made on other potential transfer points along the basin divide. More information on these sites can be found in the Focus Area 2 Appendix of the GLMRIS Report, as well as on the Focus Area 2 Other Aquatic Pathways page of this Web site.

What are the species in the report?

There are 13 ANS of concern identified in the report. Bighead carp, silver carp and scud are established in the Mississippi River with threat of potential transfer to the Great Lakes Basin. Bloody red shrimp, fishhook waterflea, grass kelp, red algae, diatom, reed sweetgrass, threespine stickleback, tubenose goby, ruffe and the viral hemorrhagic septicemia virus are established in the Great Lakes Basin with threat of potential transfer to the Mississippi River Basin.

How did you determine the species and alternatives?

The team documented 35 aquatic nuisance species established in one basin with the possibility of transfer to the other. A risk assessment narrowed down the total to 13 species that have a high or medium risk for transfer with a likelihood of adverse impact if established in the opposite basin. Risk was calculated through the below equation.

Risk = Probability x Consequence

After solidifying the list of ANS of Concern and their organism types, the team identified over 90 options and technologies available to control ANS transfer. Controls include those that modify flow within a waterway, such as hydrologic separation of the basins; those that modify the water quality of a waterway; collection and removal of ANS from a waterway; chemical application to ANS, as well as other types of controls currently in research and development. This list was refined through analyzing their completeness, effectiveness, efficiency and acceptability. Plans were then formulated and compared.

How many alternatives are described in the GLMRIS Report?

The GLMRIS Report identifies eight Alternative Plans. Each of the eight Alternative Plans utilizes one or more of these three strategies to reduce the risk of ANS transfer between basins: nonstructural controls; technological controls; and hydrologic separation.

Alternative Plans
  1. No New Federal Action – Sustained Activities
  2. Nonstructural Control Technologies
  3. Mid-System Control Technologies without a Buffer Zone
  4. Control Technologies with a Buffer Zone
  5. Lakefront Hydrologic Separation
  6. Mid-System Hydrologic Separation
  7. Mid-System Separation Cal-Sag Open Control Technologies with a Buffer Zone
  8. Mid-System Separation CSSC Open Control Technologies with a Buffer Zone

What are the nonstructural controls?

Examples of nonstructural control measures include removal (e.g., netting), chemical control (e.g., use of herbicides), controlled waterway use (e.g., inspection and cleaning of watercraft before or after entry to a water body), and educational programs. The Nonstructural Control Technologies Alternative evaluated measures that: can be implemented relatively quickly; protect human health and safety; require no construction; and have been implemented previously in North America.

What is hydrologic separation?

The GLMRIS Report defines hydrologic separation as, "the use of physical means to permanently separate two, or more, previously connected watersheds, in order to prevent the mixing of all untreated surface waters of the disconnected watersheds." Some of the alternative plans in the GLMRIS Report include installation of physical barriers—made of concrete, sheetpile, earth fill, and other materials—in existing waterways. The physical barriers would stop the flow of surface waters and aquatic species between basins, and would be designed to control overtopping up to a 0.2% annual chance of exceedance (500-year) storm event. The physical barriers are also expected to impact flood risk, water quality, and navigation.

What technologies are proposed to control ANS transfer?

More than 90 ANS control technologies were considered and screened for use in GLMRIS Alternatives. Four ANS control technologies were selected: the GLMRIS Lock; ANS Treatment Plant; Electrical Barrier; and Screened Sluice Gates. The GLMRIS Lock is a novel technology that would use ANS-treated water to flush floating plants, spores and eggs out of the lock chamber, while still allowing for vessel transportation through the waterway. The ANS Treatment Plant is similar to a conventional water/wastewater treatment plant process, where nuisance species would either be screened/filtered out or inactivated by ultraviolet radiation. Electric Barriers similar to those currently operating in Romeoville, IL would generate an electric field in the waterway to deter the passage of swimming fish. Screened sluice gates are proposed to exclude Great Lakes fish from swimming into the CAWS during backflow events.

How effective are each of the proposed ANS controls?

There is a varying level of uncertainty associated with the ability of each alternative to control ANS transfer through the CAWS; this uncertainty is further discussed in Appendix C of the GLMRIS Report.

The GLMRIS Report only addresses potential transfer of ANS through aquatic pathways. Other methods of transport, including animal (i.e. waterfowl) and human transfer may continue to pose a risk in the future.

There also is a risk that one or more presently identified ANS may transfer between the basins prior to alternative implementation. Nonetheless, these alternatives may also be effective at preventing the transfer of future ANS.

Could the alternative plans impact other uses or users of the waterways?

Lake Michigan and the CAWS support many functions, including commercial navigation, water supply, flood risk management, hydropower, recreation, and ecosystems. The ANS controls proposed in the GLMRIS Report are expected to impact many of these functions. The GLMRIS study expended great effort to examine the impacts of the Alternative Plans on waterway uses and users, and offer solutions to offset these impacts. The appendices of the GLMRIS Study Report offer a detailed look at expected impacts to: natural resources; navigation and regional economics; hydrology and hydraulics; and water quality. Each Alternative Plan also includes potential mitigation measures to offset the expected impacts. Mitigation measures include: ANS treatment plants; conveyance tunnels, reservoirs; and sediment remediation.

How much time would it take to implement the alternative plans?

Nonstructural measures could be implemented immediately; the Technology Alternative with a Buffer Zone could be implemented in 10 years; and all other alternatives could be implemented in 25 years. Full risk reduction would not be achieved until construction is complete. Construction of mitigation measures would be completed prior to or simultaneously with construction of ANS control measures. This schedule assumes that the project has a non-federal sponsor; receives capability funding; completes required lands acquisitions; obtains required permits; and is compliant with USACE policy requirements. Lastly, the schedule assumes conditional activities required by non-USACE parties are completed as necessary to facilitate timely completion of the project. A delay associated with any of these components would likely extend the time needed for project implementation and increase costs.

How much money would it take to implement the alternative plans?

Nonstructural measures are estimated to cost $68 million annually. Alternative Plans including structural measures are estimated to cost anywhere from $140 million to $220 million on an annual basis. Estimated costs for construction of the Alternative Plans including structural measures range from $8.3 billion to $18.3 billion. These costs are commensurate with the five percent level of detail in design for each alternative and may change with more detailed designs of an alternative.

Which alternative plan does USACE recommend?

The purpose of the Report was not to make a recommendation or to rank the plans. USACE's role was to paint an objective picture of several alternatives and to offer decision makers and stakeholders with various potential ANS control methods and evaluation criteria.

Why is the GLMRIS Report being released now?

GLMRIS was initially expected for completion in 2015; Section 1538 of the Moving Ahead for Progress in the 21st Century Act (MAP-21), enacted July 2012, compressed the initial study timeline and expedited the submission of a GLMRIS report to Congress to no later than 18 months following enactment. As Congress directed, the Report focuses on the CAWS, analyzes hydrologic separation, and was reported to Congress within the 18-month deadline. USACE remained committed to producing the best document possible within the expedited timeframe.

What happens now that the GLMRIS Report is released?

Alternatives presented in this document would require Congressional authorization in order to move forward with federal implementation after completing further detailed study efforts to include state, agency, and public review/comment, as well as completion of legal requirements including National Environmental Policy Act documentation, Model Certification and Independent External Peer Review.

The engagement of stakeholders will be a critical next step to try to identify and build consensus toward a collaborative path forward for GLMRIS, pending further Congressional direction and the availability of funding. ANS prevention is a shared responsibility. This report is unique because it identifies a range of options, allows for the incorporation of future technologies, and presents courses of action that may be implemented now to reduce short-term risk.

There are many complexities to consider with modifying the various existing uses of the Chicago Area Waterway System such as navigation, water conveyance/quality and flood risk management. Therefore, implementation of a plan would require significant resource allocations by other federal agencies and state/local stakeholders in order to achieve a joint solution.

In addition, USACE will continue to address the issues of invasive species by participating in the Asian Carp Regional Coordinating Committee, operating and refining the existing electric barriers, and participating in extensive monitoring of the waterways with our partners.


Other ANS Efforts FAQ

In addition to GLMRIS, the U.S. Army Corps of Engineers has taken multiple measures to prevent the transfer of ANS between the Great Lakes and Mississippi River basins. These actions include the Electric Dispersal Barriers Project, studies of various potential aquatic pathways, and ongoing monitoring of the location of Asian carp. These initiatives are described in more detail on the Other ANS Efforts FAQ page.