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| USACE, Little Rock District Here’s video of the Norfork Dam Syphon Tube on Aug. 8, 2023. The syphon tube was installed as part of the White River Minimum Flows Project. Releases from the syphon are intended to increase the downstream wetted perimeter below Norfork Dam. Brad Bates: It appears to be aerating the flow. Josh Draper: What's the flow rate on that? Tyler Nickle: Josh Draper 185 cubic feet/second. |
They need to use the syphon because none of the turbines are running because of "multiple data issues." [swl-wc]
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| USACE |
"The length of the dam is 2,624 feet. The spillway gross crest length is 568 feet, and there are twelve spillway gates. Elevation to the top of the dam is 590 feet. At a normal lake level of 552 feet mean sea level (msl), the lake covers 22,000 acres and has a shoreline of 380 miles. The lake’s level at the top of the flood pool is 580 feet msl, covers 30,700 acres with a shoreline of 510 miles, and contains 732,000 acre-feet of water....Approximately 1.5 million cubic yards of concrete were required, and the dam was said to be the fifth-largest concrete dam in the country at the time." It was one of the oldest USACE multi-purpose concrete structures. It was built with four 18' penstocks, but two of them are plugged with concrete. [EncylopediaOfArkansas]
This source calls it the country's sixth largest concrete dam.
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| USACE Facebook, Jun 9, 2020 "Each gate is open a half of a foot. The total spillway and hydropower release is just above 10,000 cubic feet per second. This is a non-damaging release. The peak rainfall runoff from Tropical Storm Cristobal poured into the reservoir around 32,000 c.f.s. Without the dam, flows downstream would be roughly 3 times higher." |
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| OzarksHistory, 1 of several construction photos |
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| HydroReview, photo courtesy Voith Hydro The two turbine-generator units are being upgraded from 31.3mw to 46.5mw. And "the water quality below the dam will be improved thanks to Voith Hydro’s dissolved oxygen enhancement technology." |
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| tklo A single turbine releases 2,900cfs. |
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| Brandon Lawrence, May 2020 |
Improving the aerationof the river explains the design of this nozzle.
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| garverusa The 42" [1.1m] pipe has the inlet far enough below the surface of the lake that it draws cooler water out of the reservoir. A steady stream of aeriated, cool water helps support "the area’s world-class fishery." |
May 2025 Flood:
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| USACE, Little Rock District posted UPDATE w/VIDEO: We are making a surcharge spillway release from Norfork Dam to prevent an overtopping as water levels continue to rise from recent heavy rainfall. Nine spillway gates will be open half a foot releasing approximately of 4,972 cubic feet per second.The total release from the spillway and hydropower units will be around 10,500 c.f.s. The spillway release will end after the flood pool crests and recedes to elevation 579’ per the water control plan. The top of the flood pool on Norfork Lake is elevation 580. The flood pool is currently at elevation 579.59 and rising. HISTORIC DATA: The pool of record at Norfork was set on April 11, 2008, at elevation 581.01. The next highest level was recorded on May 2, 2008, at elevation 580.9. Surcharge storage is extra storage created by operation of an overflow spillway. On a lake with a gated spillway, as the gates open the top of gate rises giving a bit more storage space for the flood – this operation maximizes the storage while optimizing the release. On a lake with an ungated spillway, the spillway only flows if the lake rises above the spillway. Surcharge storage is the extra volume stored in the lake due to the rise above the spillway. |
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