Dominion North Carolina Power’s (Dominion) Roanoke Rapids
and Gaston Power stations operate cooperatively and in conjunction with the
U.S. Army Corps of Engineers (USACE) Kerr Dam. The USACE operates the Kerr reservoir
according to its Rule Curve. In utilizing the rule curve, the Kerr provides
Dominion with a weekly volume of water (weekly declaration) to be released from
the three dams to the lower Roanoke River. Dominion is required by its FERC
operating license to maintain license-prescribed lake levels and certain downstream
flows from its Roanoke Rapids Dam.
The Roanoke Rapids dam always operates with a continuous release
(minimum flow) from the dam to the lower Roanoke River. The Gaston dam operates
in an on/off mode. The operating modes described below will affect the total
flow released from Gaston, but except in the case of high flood flows, it will
operate in an on/off manner.
Dominion North Carolina Power's Roanoke Rapids and Gaston
Power Stations have four distinct modes of operation. Modes are dictated by
river conditions or season. Select a mode for details, or scroll down.
Normal Operation -Water released from Roanoke Rapids Dam is used for electric
power generation to the greatest extent possible, limited only by the hydraulic
capacity of the power station (20,000 cfs). Power generation is scheduled to
meet the electric power requirements of the Dominion Virginia Power/Dominion
North Carolina Power customers, which vary significantly throughout the day
and from day-to-day. Flow release may vary from about 2,000 cfs to 20,000 cfs.
Large and sudden changes in flow release may occur at any time.
During normal operation Lake Gaston water levels are typically
maintained between elevations 199 to 200 feet.
Minimum flows from Roanoke rapids during normal operation:
December
1 – January 15, Kerr declaration < 6,000 cfs
2,000 cfs
December
1 – January 15, Kerr declaration > 6,000 cfs
2,500 cfs
January
16 – February 29, Kerr declaration < 6,000 cfs
2,500 cfs
January
16 – February 29, Kerr declaration > 6,000 cfs
Flood Control Operation
-Floodtime flow releases from Roanoke
Rapids Dam are under direction of the U.S. Army Corps of Engineers. Release
rates are primarily governed by Kerr Reservoir water level and inflow. Guidelines
for flood releases relative to Kerr Reservoir water level and inflow are:
Kerr Reservoir
Water Level (feet)
Release (cfs)
300 - 312
Up to 20,000
312 - 315
25,000
315 - 320
35,000
320 - 321
Greater of 85% of inflow or 35,000
> 321
Greater of 100% of inflow or 35,000
During flood control operation a portion of the 3 feet of
Lake Gaston flood storage (between elevations 200 and 203 feet) may be used.
Fish Spawning Operation-
During the anadromous fish spawning season (March 1 -
June 15), flow released from Roanoke Rapids Dam is regulated to provide adequate
downstream flow for spawning success. A constant sustained flow with little
variation is desirable. The recommended flow regime is:
Period
Target Flow (cfs)
Lower Limit (cfs)
Upper Limit (cfs)
March 1 – 31*
Average of Kerr’s weekly declaration
3,500
April 1 - 15
8,500
6,600
13,700
April 16 - 30
7,800
5,800
11,000
May 1 - 15
6,500
4,700
9,500
May 16 - 31
5,900
4,400
9,500
June 1 - 15
5,300
4,000
9,500
*During March, Dominion may run peak flows on five separate
days.
Toward the weekend extra water may be stored in Lake Gaston
(between elevations 200 and 201 feet) for weekend release.
Drought Flow Operation - Drought
flows released from the Roanoke Rapids Dam are determined in consultation with
the US Army Corps of Engineers (Corps) and the North Carolina Department of
Water Quality (DWQ). These flows will be determined when a drought has been
declared in the Roanoke River Basin by the Corps and DWQ.
At this time, Dominion North Carolina Power will cease its
load following operations at the Roanoke Rapids Dam and will discharge water
to the lower river per the consultation. Minimum flows during droughts stated
in Dominion's FERC license are 2000 cfs for all months except September through
November when minimum drought flows are 1500 cfs.
