Impact Of Apalachicola River Flows

The tables below contain information from the Advanced Hydrologic Prediction Service of the National Weather Service showing the impacts of sustained levels of water flow and the impacts of river stages on aquatic life in the river and bay.

Impacts Of Various Levels Of Water Flows
(Measured In Thousands Of Cubic Feet Per Second – kcfs)

30 kcfs Flow needed to inundate designated Gulf Sturgeon critical habitat below Jim Woodruff Lock and Dam.
29 kcfs Flow needed to inundate upper river floodplain (Chattahoochee to Blountstown stretch) to allow host fish to access the main channel and floodplain to assist with Purple Bankclimber and Fat Threeridge reproduction.
20.4 kcfs Successful Gulf Sturgeon spawning occurred in 2005 in flow range between 20.4 kcfs and 37.4 kcfs. All rock shoal habitat at NM 105 is inundated in this range and most (>73 %) inundated with >4.59 ft (the min. reported depth of Gulf Sturgeon spawning in any river). Roughly 87 % of the rock ledge habitat and access for spawning (> 4.59 ft depth) available to approx. 60 % of the rock ledge habitat at NM 105.
16 kcfs Minimum release in support of protected mussels, host fish for mussels, and young Sturgeon. Flow level allows connectivity between the main channel of the Apalachicola River and back channels used by host fish for listed mussels and young Sturgeon. Roughly 7,000 acres of floodplain habitat connected to the river channel.
10 kcfs Threatened Purple Bankclimber and endangered Fat Threeridge mussels mostly inundated with most mussels inundated at 8,000 cfs.
8 kcfs Most threatened Purple Bankclimber and endangered Fat Threeridge mussels inundated. Minimum flow needed to assure successful reproduction of listed mussels by maintaining host fish access to important spawning, rearing, and feeding habitats in the off channel and adjacent floodplain areas. Just several hundred acres of floodplain available for host fish.
6.5 kcfs Desired minimum flow from Jim Woodruff Dam (rather than the minimum flow of just 5,000 cfs)
6.3 kcfs Level needed to maintain a healthy Swift Slough mussel population. Higher flows are needed when the floodplain has dried out or there are other changes in the vicinity of the controlling sill.
5.6 kcfs Level needed for the Swift Slough to remain minimally connected to the river. Dissolved oxygen declines to lethal levels.
5.0 kcfs Minimum flow release from Woodruff Dam. Salinity of Apalachicola Bay changes due to extended flows at this level. Areas of increased water temperature localized dissolved oxygen changes. Minimum water level for operation of Scholz Power Plant, located just downstream of Woodruff Dam. Can function temporarily at 4,200 cfs or 37.5 ft.
4.2 kcfs Temporary (not sustainable) operating level for of Scholz Power Plant located just downstream of Woodruff Dam. Equivalent to 37.5 ft msl.

 

Impacts Of Various Stage Levels Of The River
(Measured In Feet)

80.59 This is the 500 Year Flood level.
80 Major flooding will occur.
79.09 This is the 200 Year Flood level.
78.09 This is the 100 Year Flood level. At least 60 homes and several businesses in the River Junction area will begin to flood. Railroad tracks and State Road 269 will also start to flood.
76.8 This is the 50 Year Flood level.
75.2 This is the 25 Year Flood level.
72.4 This is the “10 Year Flood” level.
69.8 This is the 5 Year Flood level.
66 The river reaches initial flood stage. Flooding will begin in the river junction areas of Mosquito Creek about .9 miles from the dam.