Q: What is the Water Management Structure?
A: The water management structure has three primary components: a gated, concrete pathway through the levee at Emiquon that can be opened or closed to allow or prevent the flow of water between the wetland and the river; facilities for scientific instruments, nets, and other devices to monitor and possibly restrict the sizes or types of organisms moving through the gates when they are open; and pumps that can remove water from Emiquon when the river is too high to allow gravity drainage.
Q: What will it do?
A: The new structure will allow us to drain excess water from the preserve to protect adjacent agricultural lands and to reduce damage to infrastructure (such as roadways, levees and the visitor use area) from waves. Additionally it can be used to allow managed, seasonal water exchanges between Emiquon and the Illinois River to create more natural water levels and fluctuations at the Emiquon Preserve. Restoring these cyclical water flows will support the Conservancy’s goal at Emiquon, which is to manage the river and floodplain ecosystem and support healthy fish and wildlife habitat at the preserve.
Q: Where will it be constructed?
A: The water control structure is being built through the current levee toward the southeast corner of the Emiquon Preserve. It will be approximately 250 feet long and 75 feet wide, utilizing gates and pumps to manage water levels and flows between Emiquon and the Illinois River.
Q: Why is this necessary?
A: While to date the responses of plant and animal communities to initial restoration efforts have been impressive, experience and science clearly show that maintaining these high-quality habitats long-term requires water management capabilities.
Native plant and animal communities at Emiquon are dependent on natural seasonal and year-to-year fluctuations in water levels, normally with floods in spring and lower, stable water levels during the summer growing season, which the structure will help restore.
The record flood of 2013 on the Illinois River left us without water management capabilities. Prior to that, water levels in the wetland could be reduced using pumps. However, pumping is expensive, both financially and environmentally, and provides fewer benefits to the ecosystem. Additionally, with only pumps, most aquatic species are unable to travel back and forth between Emiquon and the river as they need to.
Many aquatic species in the river need access to Emiquon’s wetland habitat for spawning, feeding and wintering. Other species and life stages need to move from Emiquon into the river. The water management structure provides a potential path for the movement of a variety of wildlife and nutrients between Emiquon and the Illinois River.
Q: How does it work?
A: Depending on the water level differences between Emiquon and the Illinois River, gates can be opened to allow gravity flow of water into or out of Emiquon as needed. For example, when water levels are higher in Emiquon, staff can open the structure so water from Emiquon will flow into the river. This means that we will not need to solely rely on pumps to move the water, which reduces the need for electricity and the project’s carbon footprint and is better for native species.
The gravity flow will be carefully managed – that is, the structure can be closed to stop the flow of water when necessary. Conversely, the gate will only be opened when deemed appropriate.
Q: Water management: What does that mean?
A: Water management means the drainage district, in consultation with the Conservancy and partners, will actively direct the amount and timing of water flow out of or into Emiquon by opening or closing the gates or using pumps to recreate natural water level fluctuations needed to sustain the high-quality habitats in Emiquon.
The goal of the water management structure is to help drain neighboring agricultural lands and to protect infrastructure (e.g., roadways and levees). The structure also can be used to mimic what naturally happened to floodplains during the annual water cycle before the floodplain was leveed and drained nearly a century ago. Typically, floodplains experience high water levels in the spring and lower, stable water levels during the summer growing season.
In addition, the structure will allow scientists to ensure variability in water levels that happened naturally among years. Before Emiquon was drained, large-scale floods would occur infrequently, but provided long-term benefits for wetland habitats and fish and wildlife. In-between those floods, there were drier periods with little to no flooding, which were better for moist soil plants and fish-eating birds. Occasional droughts that temporarily dried up much of the wetland were also important for conditioning sediments and providing more beneficial conditions for aquatic plants when the areas refilled with water. The connection will help restore these seasonal and year-to-year variations in water levels to ensure a high level of productivity and diversity in the plant and animal communities at Emiquon
Q: Why not just remove a section of the levee so Emiquon is permanently connected to the river?
A: An unmanaged connection, one that can’t be controlled, would harm Emiquon’s restored high-quality habitats by subjecting them to the river’s extremely altered hydrology, sediment loads, contaminants, and invasive species. The water management structure will avoid or minimize these factors, while providing Emiquon the benefits of drainage and more natural water level fluctuations.
Q: How will the water management structure keep excessive sediment, nutrients and contaminants out of Emiquon?
A: The structure makes it possible to isolate the preserve from the river when desirable to avoid heavy loads of sediment, nutrients, contaminants and/or invasive species. By providing drainage when desirable, the structure will help manage sediments in Emiquon. Long before there is a sediment problem, the gates and pumps could be used to draw water levels down, thereby drying and compacting the sediments. During the dry period, sediments could also be physically removed and used to strengthen the levee or for other beneficial purposes. Additionally, Emiquon could benefit from periodic supplements of sediment and associated nutrients provided by a controlled influx of river water.
Research conducted by the Illinois State Water Survey indicates that sediment could be adequately controlled through a managed connection such as this one.
Q: What about invasive species? Can they get in through the water management structure?
A: Invasive species could enter Emiquon through the structure, but what’s more important is that it provides a way to more effectively remove them if and when they become too abundant. Through natural dispersal methods, aquatic invasive species like common carp and Eurasian water milfoil have already entered Emiquon, and they will continue to do so. In the event that common carp or other species ever became too abundant, the structure could be used to draw water levels down to facilitate their control. This would also allow the “good fish” in Emiquon to escape to the Illinois River. In addition, grates like the ones designed for this structure have been used successfully to selectively prevent adult carp from accessing wetlands during spawning season, while still allowing natural water level variation, and the movement of nutrients and smaller organisms.
The structure will also allow scientists to experiment with new ways to inhibit movements of invasive species into Emiquon and other ways to encourage desired aquatic fish and other species to enter. We are currently investigating the use of electricity, bubbles, and sound, among others.
Q: How do you know water from the river won’t damage habitat at Emiquon?
A: First of all, water would only flow in if specifically allowed to, and any decision to let water in would take into consideration all potential impacts – negative as well as positive.
We monitored some of those effects following the flooding of 2013, when the Illinois River overtopped the levee for over six days. This “reconnection” to the river was unplanned and uncontrolled, yet we saw that rather than harm the habitat at Emiquon, the flooding may have been beneficial to many plants and animals. The area of submersed aquatic vegetation beds expanded, catches of some native fishes increased, and catches of the invasive common carp were down. Additionally, during fall migration, use-days by waterfowl were similar to 2012 and above the 5-year average, and use-days by American coots were substantially greater in 2013 compared to 2012 or the 5-year average.
The 2013 flooding also damaged a 300-foot section of the levee at the Conservancy’s Spunky Bottoms Preserve, creating an unmanaged connection to the river and completely inundating the area with flood waters. After the flood receded at Spunky, sampling by the Illinois Natural History Survey collected a record 37 fish species for the site, with native species dominating the samples. Additionally, waterfowl use during the subsequent spring migration appeared to be the greatest since restoration began there in 1999.
With funding from the National Science Foundation, scientists from the University of Illinois Springfield, Illinois Natural History Survey, and the Conservancy are continuing to evaluate the effects of the floods on these wetland habitats, but as stated above, the early evidence shows in-flow from the river has helped some habitat and fish and wildlife populations, and no adverse effects have been documented at Emiquon where the in-flow was limited.
Additionally, it’s important to remember that unlike the proposed water management at Emiquon, the flooding at Emiquon and Spunky Bottoms in 2013 was uncontrolled. Any flows in or out of Emiquon would be carefully controlled and monitored by science staff.
Q: When and how often will you open the water management structure?
A: The general pattern we want to recreate is higher waters in spring, followed by lower, stable water levels in the summer growing season. Operation will depend on habitat needs and extensively on weather and river conditions, such as how much spring rains create high water levels, and when the river is low enough in summer to flow water out of Emiquon. In consultation with Conservancy scientists and partners, the drainage district will decide when, how often and how long the water control structure should be opened, based on the needs for drainage and of the restored wetland and behavior of the Illinois River. The team will monitor the health of the wetland and open and close the gates and utilize the pumps based on what science tells them is best for maintaining Emiquon’s native plant and animal communities, within practical constraints including providing drainage for other landowners in the district.
Q: What other benefits does the water management structure provide?
A: Designed as a “science-friendly” management tool, the water management structure is key to Emiquon’s utility as a model for floodplain restoration and management. The structure will have features that will allow scientists to conduct monitoring and research, which will help the team understand the effects of water flows and movements of fishes and other aquatic species between Emiquon and the Illinois River. The structure will have two sampling bays where scientists can analyze water and monitor movements of fish and other organisms. The duplicate bays will allow the scientists to perform experiments, with one bay acting as a “treatment” and the other as a “control.” Results from this research will be shared with other floodplain scientists and managers along the Illinois River, throughout the Upper Mississippi River, and around the world.
Q: Who is doing the job?
A: The Nature Conservancy and partners completed design of the structure with engineers from two local firms: Peoria-based Maurer-Stutz and Hanson from Springfield. The Conservancy engaged partners at the Illinois Natural History Survey, University of Illinois Springfield and within its own staff and trustees, some who have lifelong experience working on the Illinois River. Laverdiere Construction Inc. of Macomb Illinois was selected as the construction contractor.
Q: How long have you been planning this connection?
A: The Nature Conservancy began working with the Army Corps of Engineers on this project in 2005. The Corps helped with the initial ecological and engineering planning and design, and they will continue to be advisors as we move forward with planning, construction, operation, and evaluation. Many other organizations have been included in discussions about the structure and its management, including the Illinois Department of Natural Resources, University of Illinois Springfield, Illinois Natural History Survey, Natural Resources Conservation Service, U.S. Fish and Wildlife Service, The Wetlands Initiative, and other private wetland managers. The effectiveness of the structure and its operation will be closely monitored and research will be shared with these and other partners.
Q: When will it be complete?
A: We broke ground early in 2015 on the water management structure and anticipate completion in less than one year.
Q: How much and who’s paying?
A: The Nature Conservancy is paying for final design and construction of the Water Control Structure. The current estimated total cost is approximately $6 million.
Q: How does the surrounding area benefit?
A: The structure will allow management of water levels to (1) drain adjacent agricultural lands, (2) protect infrastructure including roadways and levees, and (3) sustain the high-quality natural habitats and wildlife at Emiquon long term. It will re-establish the flow of high-quality foods, such as aquatic plants, insects, and fishes that move from the wetland to the river, which were lost when the area was leveed. In fact, these backwater areas, with their production of grasses and sedges, aquatic plants, phytoplankton, zooplankton, insects, fishes and other food chain essentials, were what fueled the Illinois River system when it was the most productive mussel stream and inland commercial fishery in the United States a century ago. Restoring this natural productivity will boost the related tourism, hunting and fishing in that area.
Q: Will fish and other wildlife be at risk during the construction?
A: With the exception of the immediate area of the construction (less than 4 aces), fish, wildlife and natural habitats should not impacted as water levels will not be lowered for the construction.