News & Bulletins
Great Sacandaga Lake Handles Hurricane Irene and Subsequent Tropical Events/Reduces Flooding on the Hudson
Mayfield, NY – Conklingville Dam and Great Sacandaga Lake minimized the effects of heavy rainfall associated with the remnants of Hurricane Irene, preventing flooding on the Hudson River from Hadley to Fort Edward, and reducing the severity of flooding from Fort Edward to Albany.
The Great Sacandaga Lake watershed received approximately 5.5 inches of rain from Irene causing the reservoir to rise about 3 feet. Precipitation from the storm produced sharp rises in the Sacandaga and Hudson River. Inflow to the reservoir peaked at more than 40,000 cubic feet per second (cfs) during the afternoon on August 28 and produced an average of 20,000 cfs for the day.
Without the benefit of flood protection and storage capacity at Great Sacandaga Lake, the Hudson River would have exceeded flood stage at Fort Edward by more than 5 feet. By reducing the flow in the Hudson River by at least 20,000 cfs, the flood protection benefit provided by the reservoir reduced the flood stage at Waterford, Green Island, and Troy by nearly 2 feet.
The elevation of the Great Sacandaga Lake was lowered more aggressively, consistent with the Offer of Settlement operating rules, to an elevation of 762.6 feet by the morning of August 28 in anticipation of significant inflow. Increasing the release of water from the reservoir for about four days before the storm provided an additional 700,000,000 cubic feet of storage capacity.
Great Sacandaga Lake is poised to efficiently deal with current tropical rain events following Irene. The peak elevation of the reservoir resulting from the most current rainfall is estimated to be approximately 770 feet above sea level. Release of water from Great Sacandaga Lake will begin as soon as the flow rate of the upper Hudson River allows.
The Hudson River – Black River Regulating District is a State of New York public benefit corporation which provides river regulation, including flood protection and low flow augmentation, in the Hudson and Black River watersheds through the operation of water storage reservoirs, including the Great Sacandaga Lake, Indian Lake, Stillwater Reservoir and the Fulton Chain of Lakes.
Mayfield, NY – On Saturday, May 7, as a precautionary measure, the Hudson River – Black River Regulating District activated the Conklingville Dam Emergency Action Plan (EAP) in response to an unusual change in a measurement taken at one of the monitoring points within the dam. Beginning immediately and continuing around the clock, the Regulating District’s Engineering staff has conducted intensive, physical and visual inspections of conditions at the Conklingville Dam. The Regulating District has determined that the unusual change in measurement triggering the alert resulted from a data reading error. As a result, the emergency action plan has been deactivated.
Mayfield, NY – On Saturday, May 7, as a precautionary measure, the Hudson River – Black River Regulating District activated the Conklingville Dam Emergency Action Plan (EAP) in response to an unusual change in a measurement taken at one of the monitoring points within the dam.
Readings taken at the monitoring point require the measurement of the water table within the dam using electronic equipment designed to sense the presence of water. The surface elevation of the water within the dam is measured with a sensor that is lowered into a 1-inch diameter pipe which extends approximately 75 feet below the surface of the dam. Consistent with the Regulating District’s dam safety plan and its procedures for monitoring during high reservoir elevation events, the frequency of measurements was expanded to include weekend monitoring.
Saturday’s unusual readings lead engineering staff to prudently activate the EAP as a precautionary measure. Condition B of the EAP is intended to notify emergency responders of a potentially hazardous situation.
Since the activation of the EAP, Regulating District engineering staff have re-evaluated and thoroughly reviewed the monitoring point data and the data collection process used by field personnel during the past week. Regulating District officials have been in contact with their geotechnical engineer and dam safety engineers from the Federal Energy Regulatory Commission (FERC) to make a preliminary assessment of the situation. At this time engineers are focusing on the accuracy of the data and possible shifting of the monitoring equipment or reference point as the cause for the unusual change in measurement.
Regulating District engineers plan further consultation with federal dam safety officials and the project geotechnical engineer on Monday, May 9, to rule out any other possible cause for the unusual measurements. At that time, it is likely the emergency action plan will be deactivated.
Mayfield, NY – The Hudson River – Black River Regulating District continues to monitor the condition of the Conklingville Dam on an hourly basis as part of its response to the unusual change in the water pressure measured Saturday afternoon at one of the monitoring points within the dam.
The unusual pressure measurement prompted the Regulating District to activate the Conklingville Dam Emergency Action Plan (EAP) at approximately 8 p.m. yesterday as a precautionary measure.
Water pressure at the monitoring point appears to have stabilized and no additional changes in the condition of the Conklingville Dam have been observed.
Failure of the dam has not occurred and there appears to be no imminent threat of failure.
An update on the condition of the dam and the status of the emergency condition is planned and will be provided to local and state emergency management officials early Sunday afternoon.
Water continues to be discharged through outlet valves and the E. J. West hydroelectric facility at Conklingville Dam in response to the emergency condition.
Regulating District engineers will consult federal dam safety officials and the project geotechnical engineer on Monday, and develop a plan to investigate the unusual condition.
Mayfield, NY – The Hudson River – Black River Regulating District has activated the Conklingville Dam Emergency Action Plan in response to an unusual change in the water pressure within the dam at Conklingville, Town of Hadley, Saratoga County.
At 8:00 pm, this evening the Regulating District declared a “Condition B” emergency. A Condition B emergency means that a potentially hazardous situation is developing. Failure of the dam has not occurred, but the Regulating District is taking action to minimize the potential for dam failure.
Notification of the emergency condition has been given to emergency management agencies in Saratoga, Washington, and Warren County, the state emergency management office, dam safety agencies, and to emergency response personnel downstream of the Conklingville Dam.
The Regulating District has maximized the release of water from Great Sacandaga Lake in response to the emergency condition.
Regulating District staff will continue conducting hourly monitoring of the condition of the Conklingville Dam until the emergency condition is no longer necessary.
Mayfield, NY – Precipitation received and forecast during the next several days, when combined with the last of the melting mountain snow, is producing expected increases in the reservoir elevations at the New York State reservoirs operated by the Hudson River-Black River Regulating District. While many of the Regulating District’s reservoirs are now at full capacity, the design of those impoundments ensures that only a small fraction of the water flowing into the reservoirs will get released over the dam. For example, even when water crests the spillway, only one sixth of the water flowing into Great Sacandaga Lake in the next few days will immediately flow over the Conklingville dam spillway down to the Sacandaga and Hudson Rivers. The rest is retained for release once the natural flow of the Hudson River returns to predetermined target elevations. While the torrent of water flowing over the Conklingville Dam makes for interesting photography, the volume released over the spillway is a fraction of the water typically released through the dam’s Dow valves and the adjacent E.J. West hydropower plant.
Winter-time drawdown of the state’s river regulating reservoirs occurred on schedule and as planned. The Great Sacandaga Lake was lowered according to the Upper Hudson/Sacandaga River Offer of Settlement and reached a minimum elevation of 749.07 feet on March 5, 2011 consistent with the Offer of Settlement elevation target curve. Since that date, above average steady rain and snow melt has brought the elevation of the Great Sacandaga Lake to nearly 773 feet. Weather and river forecasts by the National Weather Service (NWS) and the United States Geologic Service (USGS) yield a prediction of a peak elevation at Great Sacandaga Lake at 774.4 feet on Sunday May 1, 2011. This elevation will be an all-time high. Because natural flow of the Hudson River is already above flood stage, the Regulating District will continue to impound as much water as possible until the weather improves.
Once the weather does improve, the inflow into the Hudson River’s headwaters in the Adirondacks will decrease. At that time, the Regulating District will begin daily Reservoir releases to drawdown Great Sacandaga Lake in anticipation of continued spring and summer rains. Significant additional rainfall, which could be expected to cause the Great Sacandaga Lake’s elevation to rise, may require immediate release of water at Conklingville to the Sacandaga and Hudson Rivers at or near flood stage in order to prevent triggering larger volume releases designed to protect the impoundment itself. None-the-less, even should additional significant rainfall occur, the Reservoir’s remaining storage capacity and design ensure that the Reservoir will continue to mitigate the potential for widespread flooding by limiting releases at Conklingville to levels below the inflow to the Reservoir from the headwaters of the Sacandaga River.
Mayfield, NY and Watertown, NY – The river regulating reservoirs operated by the Hudson River – Black River Regulating District have been, and are prepared to, receive runoff produced by recent rainfall and melting snow consistent with our mission to regulate the flow of the Hudson River and Black River for the purposes of flood protection and flow augmentation.
Precipitation received and forecast during the next several days, when combined with melting snow, is producing expected increases in reservoir elevations. In response to such increases, the Regulating District will be increasing the release at Stillwater later this afternoon from 600 cfs to 1000 cfs. The Beaver River Flow at Croghan will increase from approximately 1800 cfs to 2200 cfs. Similarly, the Regulating District will increase the release at Indian Lake from 400 cfs to over 750 cfs. Additional releases from the Regulating District’s Conklingville Dam will commence early next week as outlined under the Offer of Settlement.
Winter-time drawdown of the state’s river regulating reservoirs has occurred on schedule and as planned. The Great Sacandaga Lake was lowered according to the Upper Hudson/Sacandaga River Offer of Settlement and reached a minimum elevation of 749.07 feet on March 5, consistent with the Offer of Settlement elevation target curve. The Stillwater Reservoir was lowered to an elevation of 1665.50 feet by March 5, consistent with its operating plan.