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| Dam Name: | Crab Orchard |
|---|---|
| NID ID: | IL10000 |
| Longitude: | -89.15 |
| Latitude: | 37.71 |
| Map Section: | S.19-30,T.9S,R.1E |
| County: | WILLIAMSON |
| River: | CRAB ORCHARD CREEK |
| State: | IL |
| Distance: | 3.00 miles |
| Owner Name: | DOI FWS |
| Owner Type: | F |
| Private Dam? | No |
| Year Completed: | BLAN |
| Dam Length: | 3800 feet |
| Dam Height: | 64 feet |
| Maximum Storage: | 87500 acre-feet |
| Normal Storage: | 57800 acre-feet |
| Surface Area: | 9500 acres |
| Drainage Area: | 215 square miles |
| Hazard Potential: | |
| Emergency Action Plan? | No |
| Inspection Frequency: | 2.00 |
| State Regulated Dam? | No |
| State Regulating Agency: | NONE |
| Spillway Type: | |
| Spillway Width: | 411 feet |
| Number of Locks: | 0 |
| Federal Design Agency: | Department of Interior; Fish and Wildlife Service |
| Federal Construction Agency: | Department of Interior; Fish and Wildlife Service |
| Federal Regulatory Agency: | Department of Interior; Fish and Wildlife Service |
| Federal Inspection Agency: |
Department of Interior; Fish and Wildlife Service |
| Federal Operating Agency: | Department of Interior; Fish and Wildlife Service |
| Federal Owner (Agency): | Department of Interior; Fish and Wildlife Service |
| Other Federal Agencies: | |
| Source Agency: | Department of Interior; Fish and Wildlife Service |
Dam Safety For Boats
A large amount of water can be released from a dam without any warning at any time and by any means. For example, when the demand for electricity is high, the turbines at a dam may be turned on automatically, resulting in a significant increase in the downstream flow of water in only a matter of seconds.
If there's a need to release water through the sluiceways (outlets at the base of the dam), this operation can also create a great swell of discharged water downstream.
During flood operations, any or all spillway gates across the width of a dam can be opened to release upstream flood water that needs to pass to the next downstream reservoir. Upstream or downstream, even the most experienced boater with the strongest motor is no match for this strong flow of water plunging over a spillway of a dam. Even if you're boating far downstream of a spilling dam, recirculating current can pull a powerful boat upstream toward plunging water that could shred any boat.
Some dams equipped with navigation locks create turbulent water as well. When vessels pass through, strong flow is released near the exhaust ports of the wing wall of the lock.
Warning Systems At Dams
To warn reservoir users of potential danger, warning devices are installed at many dams:
- Horns: Horns are sounded before water is released from the powerhouses, sluiceway or spillways. When you hear these horns, leave the areas upstream and downstream of the dam immediately.
- Strobe Lights: Strobe lights are activated before the hydro plant begins generating electricity at the powerhouse or releases water through the spillway or sluiceway. When you see these strobe lights flash, leave the areas upstream and downstream of the dam immediately.
- Warning Signs: Signs direct visitors to stay clear of hazardous areas and warn of rapidly rising water and sudden spillway and turbine water surges. Take them seriously—obey all warnings!
