Finding of No Significant Impact and Decision to Repair Crab Orchard Lake Spillway

Crab Orchard National Wildlife Refuge 

Marion, Illinois


The U.S. Fish and Wildlife Service (Service) is proposing to perform repairs on the Crab Orchard Lake spillway at Crab Orchard National Wildlife Refuge (refuge). To facilitate these repairs, partial draw down of Crab Orchard Lake (lake) will be required. Safety Inspections of Crab Orchard Lake spillway indicate that repairs are needed and repairs to the spillway are apriority for the Service’s Dam Safety Program. Not correcting these issues could lead to an uncontrolled release of water that would affect water supplies (for recreation, wildlife, and the Haven), alter refuge habitats and wildlife populations, reduce the refuge’s recreational opportunities by as muchas75%, and potentially cause off-refuge impacts.

Selected Action

Alternative B—Proposed Action Alternative: Repair of Crab Orchard Lake Dam Spillway

Under the Proposed Action Alternative, the refuge would open the Crab Orchard Lake spillway screw gates, beginning July 6, 2021, and discharge water until a maximum of a four-foot draw down of the lake is achieved. It is predicted that this process will occur over a four to eight-week period, (one-half to one foot per week) barring any major rainfall events. Consideration has been taken to conduct this project when it will have the least impact to the refuge, its resources, and the general public. Lake elevations will be maintained at four feet below the “normal pool” elevation of 405 feet Mean Sea Level for the duration of the spillway repairs. The repairs include renewing the concrete on the crest of the dam and adding structural support to the backside of the spillway. Over time, the concrete on the crest of the dam has become worn and pitted. Thecontractorwillremove12-16" of concrete along the crest spillway and replace with new concrete. On the backside of the spillway, the contractor will add concrete "stair-steps" to increase the integrity of the structure Following repairs, the screw gates would be closed, and the lake would refill to “normal pool” through natural rainfall and runoff events. The lake could be back to normal levels or resuming normal levels byFebruary2022.

This alternative was selected over the other alternatives because it helps meet the purpose and needs of the Service, it would lead to repairs of the Crab Orchard Lake spillway, maintain the lake’s wildlife and habitats, provide wildlife-dependent recreation opportunities, maintain the Haven’s water supply, protect critical infrastructure, protect life and property downstream, and allow Crab Orchard Lake to continue to be a significant contributor to the local economy. Additionally, this alternative meets the Service’s priorities and mandates to “assist in the maintenance of adequate water quantity and water quality to fulfill the mission of the System and the purposes of each refuge” (16 U.S.C. 668dd (a)(4)(F), ensure the continued provision of opportunities for compatible wildlife-dependent recreational uses, and fulfill the Service’s mandate for administering the National Wildlife Refuge System under the National Wildlife Refuge System Improvement Act.

Alternatives Considered and Analyzed

Alternative A—No Action Alternative

This alternative would continue the status quo. Crab Orchard Lake would remain at normal pool elevation, with the fluctuations in lake elevations being altered only by normal drying and precipitation cycles. Recreational opportunities, including fishing, boating, hunting, skiing, swimming, wildlife viewing, etc. would remain largely unchanged by management activities. Facilities for boaters and the Crab Orchard Marina houseboat users would remain under normal operation. Illinois Department of Natural Resources and the Service would continue to manage the lake fisheries as they currently are, and the Service would manage and maintain all other activities under the same policies and objectives. However, needed repairs on the spillway would not be pursued. The condition of the dam would continue to decay and the risk of an uncontrolled release caused by failure of the spillway would continue to increase over time.

This alternative was not selected, because The No Action Alternative does not meet the purpose and need for the action to maintain the integrity and safety of the Crab Orchard Lake dam to provide continued management of the lake’s wildlife and habitat, provide safe wildlife dependent recreation, maintain the Haven facility non-potable water supply, and protect life and property downstream. If the spillway is not repaired, it could result in an uncontrolled release causing substantial on and off-refuge impacts. Impacts include the loss of recreational opportunities on Crab Orchard Lake, the loss of water supplies critical to the continued operation of the Haven, and negative effects to a wide array of wildlife and their habitats. Emergency repairs after a failure and uncontrolled release would also be much more costly than the current proposed repair action. Additionally, this alternative does not meet the Service’s priorities and mandates.

The No Action Alternative also only further perpetuates the degraded state of the lake. Shoreline erosion, high turbidity, deep unconsolidated flocculent sediments, high planktivore and benthivore fish populations, lack of fish escape, spawning, and nursery habitats would all continue along the current trend that degrades habitat. Catastrophic changes to the lake’s habitats and species, as well as severe off-refuge impacts, may be realized in the event of an uncontrolled release resulting from failure to address the spillway deficiencies. 

Alternatives Proposed but Not Analyzed.

In addition, to the two alternatives evaluated in the Environmental Assessment, the Service considered two other alternatives that were eliminated from further analysis.

Partial Draw down of Crab Orchard Lake with Coffer dam and Repair of Dam Spillway

The refuge originally planned for a two-foot drawdown that included a cofferdam to facilitate repair of the dam and spillway. This alternative consisted of drawing the lake down two feet below “normal pool” and constructing a cofferdam around the spillway to dewater the area where repairs are needed. This alternative was considered for less impact to facilities and boats on the lake, particularly to the Crab Orchard Marina and houseboat users. However, under this alternative several boats may still have had to be moved or removed from the lake.

This alternative was considered to be infeasible due to economic reasons. The refuge sought bids in two separate announcements in 2019 and 2020. None of the bids that were received fell with in the Service’s guidelines and therefore could not be taken into consideration. In addition, the bids received on the last occasion greatly exceeded available funds. Although this alternative meets the purpose and need of this action, due to the Service being unable to obtain cost effective bids that meet the guidelines, this alternative was note valuated further.

Removal of the Dam

Removal of the dam does not meet the purpose or need of this action. This alternative was not considered as it conflicts with the mission of the refuge and the Service’s priorities and man dates as outlined by the National Wildlife Refuge Improvement Act (Improvement Act) to “assist in the maintenance of adequate water quantity and water quality to fulfill the mission of the System and the purposes of each refuge” and “ensure that opportunities are provided within the System for compatible wildlife-dependent recreational uses” (16 U.S.C. 668dd (a) (4)). Without a properly functioning and safe dam to maintain Crab Orchard Lake, the refuge would be limited in meeting all its purposes. In addition, the loss of Crab Orchard Lake would likely have devastating consequences both locally and regionally to the residents, cities, towns, economies, businesses, recreational opportunities, fish and wildlife including migratory birds, local water supply, etc. For these reasons, this alternative was not considered.

Summary of Effects of the Selected Action

An Environmental Assessment (EA) was prepared in compliance with the National Environmental Policy Act to provide decision-making framework that 1) explored a reasonable range of alternatives to meet project objectives, 2) evaluated potential issues and impacts to the refuge, resources and values, and 3) identified mitigation measures to lessen the degree or extent of these impacts. The EA fully evaluated the effects associated with two potential alternatives. It is incorporated as part of this finding.

Implementation of the agency’s decision would be expected to result in the following environmental, social, and economic effects:

There is potential for several positive physical and chemical changes. Flocculent sediments are expected to consolidate in exposed areas that should experience shrinking and reduced depths of these organic bottom sediments during drawdown. Temporary reductions in water nutrient concentrations and turbidity are expected until the lake returns to normal pool. Turbidity may substantially decrease if certain plant species, such as Sago pondweed (Sago spp.) proliferate and reduce turbulence. Increased herbaceous and woody vegetation produced in exposed areas during the draw down are expected to bind soils and reduce wave energies following there turn to normal pool. This will reduce erosion potential, slowing future shoreline erosion, and thus reduce turbidity. Low water levels for extended periods will allow exposed soils to aerate which increases future availability of nutrients and subsequent vegetative responses. Long-term positive effects on the lake’s fisheries are expected, which will increase the quality of angler experience for several years following the lake returning to normal pool. Additional shallow water habitats will become available and receive increased dabbling duck use. Vegetation diversity and abundance may improve following the drawdown, which could improve waterfowl use and hunting opportunities.

Houseboats will need to be removed from the Marina and the Crab Orchard Beach will likely be closed due to lack of water. Some boat ramps will be accessible for continued recreation on the lake. Overall, anticipated reductions in recreational opportunities are expected to be of such short duration that effects will be negligible in terms of socioeconomic impacts at local, regional, and national levels. The economic inputs from Crab Orchard Lake, vital to local communities, will be preserved under this alternative. Improvements to water quality, the lake fishery, and waterfowl opportunities under this alternative will only further enhance visitation to the area and therefore economic inputs.

Measures to mitigate and/or minimize adverse effects have been incorporated into the selected action. These measures include:

  • Regulating the rate of discharge will be an important factor in partially drawing down the lake. Fish kills can be a concern, especially during hot weather. If the lake is drawn down too quickly, the thermocline can be disrupted and could potentially cause a fish kill. If fish start to die, discharge may be regulated to offset this impact. It can be expected that fish populations will be concentrated for a short period. This would be for the duration of the repair plus the time it takes the lake to reach normal pool after project completion.
  • There is a risk of the spread of invasive plant species during the drawdown. Phragmites can spread vegetatively to recently dried habitats, and Eurasian milfoil and Curly leaf pondweed could spread to deeper areas of the lake while it is low. These migrations are expected to be short lived, as these habitats will not be suitable when normal lake levels return. However, USFWS and Illinois DNR will monitor these populations and implement control measures to prevent or stop their spread.
  • There is the potential to expose both documented and undocumented cultural resource sites that occur underneath the water’s surface during the partial drawdown of the lake. Efforts will be made by refuge staff to monitor potential cultural resource sites on a weekly basis. If refuge staff or contractors discover any artifacts, the Regional Historic Preservation Officer will be immediately notified for consultation on the necessary steps to protect these cultural resources [and the area secured from possible collectors]. If this does occur, law enforcement will be made aware of the situation and potential exposure of artifacts. Patrols will be increased in the event exposure of artifacts increases.
  • Impacts are expected to users of Crab Orchard Lake, primarily to the Marina and houseboat users. The refuge is providing options for temporary storage or mooring. Tenants will be credited the following year for all time lostin2021.

While refuges, by their nature, are unique areas protected for conservation of fish, wildlife and habitat, the proposed action will not have a significant impact on refuge resources and uses for several reasons:

  • The action will result in beneficial impacts to the human environment, including the biodiversity and ecological integrity of the refuge, as well as the wildlife-dependent recreational opportunities and socioeconomics of the local economy, with only negligible adverse impacts to the human environment.
  • The adverse direct and indirect effects of the proposed action on air, water, soil, habitat, wildlife, aesthetic/visual resources, and wilderness values are expected to be minor and short-term. The benefits to long-term ecosystem health that these efforts will accomplish far outweigh any of the short-term adverse impacts discussed in this document.
  • The NWRS uses an adaptive management approach to all wildlife management on refuges, monitoring and re-evaluating the hunting and fishing opportunities on the refuge on an annual basis to ensure that the hunting and fishing programs continue to contribute to the biodiversity and ecosystem health of the refuge and these opportunities do not contribute to any cumulative impacts to habitat or wildlife from climate change, population growth and development, or local, State, or regional wildlife management.
  • The action, along with proposed mitigation measures, will ensure that there is low danger to the health and safety of refuge staff and visitors.
  • The action is not in an ecologically sensitive area.
  • The action will not impact any threatened or endangered species; or any Federally designated critical habitat.
  • The action will not impact any cultural or historical resources.
  • The action will not impact any wilderness areas.
  • There is no scientific controversy over the impacts of this action and the impacts of the proposed action are relatively certain.
  • The proposal is not expected to have any significant adverse effects on wetlands and floodplains, pursuant to Executive Orders 11990 and 11988 because the project will be largely confined to the lakebed.

Public Review

The proposal has been thoroughly coordinated with all interested and/or affected parties. Public review included the following measures:

On April 19, 2021, the Service released the Draft Environmental Assessment documents for public review. Following the release of the Draft EA, the Service opened a 15-day public comment period that ended on May 04, 2021. Members of the public were notified of the availability of the Draft Environmental Assessment through a press release posted on the Service website. A press release was sent out to 32 media contacts, as well as congressional offices on April 19, 2021. The Environmental Assessment and associated information, such as public meeting times, were posted on the Crab Orchard NWR website on April 19, 2021 as well. The public meetings were announced on WSIL TV 3 on April 30, 2021. On April 22, 2021, the Service posted a notice on the refuge Facebook page with a link to the draft documents and how to submit official public comments. Crab Orchard National Wildlife Refuge also hosted outdoor public meetings on April 27 and 29, 2021 from 6:00 p.m. to 7:00 p.m. at the Prairie Creek Recreation Area. Comments were recorded both via note taker and on provided public comment forms. The public was also encouraged to submit comments regarding the Draft Environmental Assessment to the Service directly via either email to, by phone, or by mail to be considered part of the official administrative record fort his project.

Finding of No Significant Impact

Based upon a review and evaluation of the information contained in the EA as well as other documents and actions of record affiliated with this proposal, the Service has determined that the proposal to implement the dam spillway repair on Crab Orchard Lake on Crab Orchard NWR as described as Alternative B in the attached Final Environmental Assessment does not constitute a major Federal action significantly affecting the quality of the human environment under the meaning of section 102 (2) (c) of the National Environmental Policy Act of 1969 (as amended). As such, an environmental impact statement is not required.


The Service has decided to proceed with the repair of the Crab Orchard Lake spillway. The successful contract bidder will remove 12-16" of concrete along the crest spillway and replace with new concrete. On the backside of the spillway, the contractor will add concrete "stair-steps" to increase the integrity of the structure. This will require a drawdown of the lake elevation starting July 6, 2021. The lake level will be four feet below normal pool as early as August 1, 2021 and maintained at or near that elevation for the duration of the construction project. The anticipated timeline for completion is February 2022, at which time the lake may be back to normal levels or resuming normal levels dependent on rainfall and runoff.

The action is consistent with applicable law sand policies.


Suzanne C. Baird, Regional Chief, NWRS

Finding of No Significant Impact and Decision to Repair Crab Orchard Lake Spillway document