Dam Concerned Citizens Inc.

Gilboa Dam Updates

December 2006

A barge was anchored about 200 yards upstream from the Gilboa Dam face on the Schoharie Reservoir. It was being used as a platform for a drilling rig where core samples were being taken of the Schoharie Reservoir floor and bedrock. This drill rig sprang a leak and spilled a small amount of hydralic hose fluid into the resevoir. Normally the hoses are supposed to contain a nontoxic form of oil such as one with a vegetable base. OOPS, someone goofed!! A containment system was set up around the oil and the spill was promptly cleaned up.

February 26, 2007

The following is a presentation from DCC to the County Board of Supervisors and a letter sent to DEPs Paul Rush and Tina Johnstone.

Good Morning, I am Cindy Barber, representing Dam Concerned Citizens and the Public of Schoharie, Montgomery and Schenectady counties. The heavy snowfall we received this week raises two questions regarding the potential for serious flooding of the Schoharie Valley in the next 8 weeks. This snow pack coupled with the fact that the Schoharie Creek is ice bound with a foot of ice from its source at Hunter Mountain in Greene County to Fort Hunter, near its confluence with the Mohawk River in Montgomery County creates an ominous scenario for ice jam induced flooding if a rapid snow melt occurs with a prolonged heavy rain. In the top 10 Historical Crests, the floods of April 4, 1987, April 3, 2005, March 21, 1980 and April 5, 1984; numbers 3-6, were floods caused by rapid snowmelt and heavy rain. Due to the amount of ice we have at present and the possibility of ice jamming, not a factor in the above mentioned major floods, there is additional concern this year. With these facts in mind, we would like Chairman Van Wormer to please answer the following two questions: 1. Is NYCDEP implementing its reservoir drawdown program to compensate for heavy snow pack in the 314 square mile Schoharie Reservoir Watershed? 2. Are the Flood Alert Sirens promised for January 2007, in place and operational? If not, when will they be installed and operational? 2/26/07

These are the received answers:

DCC was told that our siren installation was not started on time due to Federal Government Homeland Security supersceding our order. We were told that we should be expecting delivery and work to begin at any time, unless the Government needs additional sirens.

UPDATE:4 of the 8 sirens have been delivered.

The original snow pack water measuring system installed by DEP was removed. The "pillows" were found to be leaking antifreeze, thus causing the cells to freeze and proper readings could not be obtained. Tubes are now being used. These tubes are driven down into the snow, then capped off, the snow allowed to melt, and the water measured is then halved to determine how much the resevoir level will be reduced.

From: sherrie bartholomew Date: February 28, 2007 12:18:28 PM EST To: Paul Rush Cc: J.I. Garver, Alex Bartholomew, Subject: activating the siphons at Gilboa Paul and Tina, Good morning. I hope this letter finds you well. I am writing regarding releasing water from the Schoharie Reservoir via the 4 siphons in advance of what is certain to be a major snow melt that will occur sometime in the next 6 weeks. We have been told that the snow pack contains upwards of 3.5" of water at present. Foul weather is forecast for Friday which will further saturate the snow in the Catskills with water. These "Frozen Assets" will be released sometime soon, as spring approaches. The ground is frozen to a depth of several feet, as there was little ground cover prior to the big snow fall of 2/14/07. Thus, the scenario exists for a major flood, should the snow pack of 314 sq. mi. Schoharie Reservoir catchment area melt in concert with a large amount of rain. Such an event occurred Jan. 18&19, 1996. In that case the ground was not frozen to the extent that it is now. Also, the Schoharie Creek was not ice bound as it is this year. The very cold weather of late Jan. and all of Feb. 2007 has caused ice to form on the Schoharie Creek both above and below the Gilboa Dam. By releasing water now via the siphons, the water could incise the ice in the Schoharie Creek, causing it to break up with less threat of forming ice jams and causing serious flooding (due to back up of water) rather than what might occur if release of water were postponed. If ice of this magnitude is in the Schoharie Creek at a time of a major spillage at Gilboa, the potential exists for major property damage and possible loss of life. In the January '96 flood, Route 30 was covered in many places by several feel of water. Fortunately, the flood waters receded on Friday night, 1/18, as a cold front and sub-freezing weather abruptly ended run off and by Sat. morning, 1/19/96 Rt. 30 was passable from Schoharie to North Blenheim. Should a similar amount of water, actually anything in excess of 43,000 cfs. occur at Gilboa in the next 6 weeks with the ice still present on the Schoharie Creek, a catastrophe will occur. The ice will be lifted out of the creek channel and float at a high rate of speed (in excess of 7 mph) downstream, hopping banks, blocking route 30 and potentially sweeping away property and people. When the waters recede roads will be choked with ice and debris. While the prospect for a high crest at Gilboa is diminished by the presence of the 220'X5.5' Notch at the spillway ele. 1130', the spectre of a large volume of ice laden water rushing down stream at a high velocity is frightening. Early, preemptive releases will insure less water down stream later as, some run off is bound to be retained by the Gilboa Dam. Also, by drawing down the Schoharie Reservoir to the effective working limits of the siphons, these very releases works themselves will be protected from ice damage should a sudden rise of the Schoharie Reservoir and run off occur above the Gilboa Dam. One needs to also consider the fact that there is 29 miles of ice upstream of the Gilboa Dam. Prattsville is painfully aware of the destructive potential of this ice! Should that upstream ice come rushing down the Schoharie and flow over the top of the Gilboa Dam, the potential exist for serious damage to, if not destruction of, the 4 siphons. Thus, I ask again, that you give serious consideration to drawing down the Schoharie Reservoir now while there is still time to do so. I am not unaware of the implications of the release of water through the siphons on residents of the Schoharie and Mohawk Valleys. Increased stream flow, due to water released via the siphons, should cut the ice and float it down stream in a controlled manner as the water in the creek at Gilboa should not exceed 500 cfs. This ice will ultimately either breakup and melt, stay on the banks of the Schoharie Creek or find its way to the Mohawk River. On the other hand, should the ice go out suddenly, with a big snow melt accompanied by rain, it will jam and break up in a series of "pulses" that will have a devastating effect in Schoharie, Montgomery and Schenectady Counties. I noticed that at 9:30 a.m. 2/28/07, the release from the Shandaken Tunnel was at 195 cfs. We understand that since the "State of Emergency" was lifted at Gilboa Dam with the installation of the last post tensioned anchor, releases via the Shandaken Tunnel have been reduced by court order. Hence, the only viable way to deal preemptively with the problem now at hand, is to start using the siphons now. I am enclosing the email address and business phone # of Dr. John Garver, Geologist and specialist in Ice Jamming on the Mohawk River. He is Professor of Geology at Union College, Schenectady, NY. Also, included is the phone # of Mr. William Van Hoesen, Director of Emergency Management for Schenectady County. Thank you, Howard R. Bartholomew, Dam Concerned Citizens Dr. John Garver William Van Hoesen...

March 1, 2007

Press Release From Schoharie County:

CITY AIMS TO BEGIN SNOWPACK-BASED FLOOD CONTROL PROGRAM AT SCHOHARIE RESERVOIR NEXT WEEK EQUIPMENT BEING BROUGHT TO GILBOA TO DE-ICE SIPHONS

Schoharie County Board of Supervisors Chairman Earl VanWormer and New York City Department of Environmental Protection (DEP) Commissioner Emily Lloyd announced today that the DEP is bringing de-icing equipment to the Gilboa Dam with the goal of using siphons at the Dam to begin a flood control program at the Schoharie Reservoir next week. Chairman VanWormer said, " I would like to thank the New York City Department of Environmental Protection and Commissioner Lloyd for keeping us informed as issues develop with the Gilboa Dam. We, the Board of Supervisors, realize that sometimes things happen that interfere with doing work, but we expect that the NYCDEP will get the situation taken care of in a timely manner, as the safety of our residents is our top priority." Commissioner Lloyd said, "We are taking this step to alleviate some of the concerns of Schoharie residents about the potential for flooding when the existing snow cover melts. The full-scale reconstruction of the Gilboa Dam will include flood gates and release works with a capacity that exceeds State guidelines. Until that work is complete in 2011, we will attempt to use the siphons in Gilboa to provide some measure of protection for people downstream." The new flood control program would aim to use siphons that were left in place after construction at the Gilboa Dam in order to maintain, when possible within the limitations of the siphons, a void in the reservoir equal to one-half of the melted snowpack in the Schoharie watershed. Four large siphons, each with a maximum capacity of 125 million gallons per day, were installed at the Gilboa Dam last year at the start of a project to stabilize the dam. Inspections of the siphons this week showed that they are currently unusable because of ice buildup inside their steel pipes. DEP will have equipment at the dam later this week to begin the process of de-icing the siphons, and expects to have them operational by the later part of next week. DEP manually surveys the snowpack around the Schoharie Reservoir every two weeks - more often when there is significant change to the snowpack - and estimates how much water it contains. Those surveys, combined with data received from the National Weather Service, will be used to determine when to operate the siphons in order to determine the void in the reservoir. In December, the DEP completed a $24 million project to bring the Gilboa Dam up to State standards for existing dam construction. A full-scale, $300+ million reconstruction project from 2008 to 2011 will bring the dam up to the more stringent State standards for new dam construction. The DEP has committed to including flood gates and large, new release works as part of the full-scale reconstruction project. # # #

Update: Siphons are now running, the graph of the Dam reservoir level will show water dropping, if you use the Minekill USGS link to check the water level there it shows very little difference. This was explained to Supervisor Tony Van Glad as the same amount of water is flowing out of the Power Authorities resevoir as what is coming in and it isn't visible because of ice on top of the reservoir at Minekill.

The next phase of work, to begin as soon as possible spring of 2007, is sediment removal in front of the intake chamber of the 18.6 mile long Shandaken Tunnel. This conducts Schoharie Reservoir water to the Esopus Creek and Ashokan Reservoir in Ulster County. The "Tunnel" has not been able to operate at full capacity, approx. 1000 cfs (cubic feet per second) for years because its opening on the Schoharie Reservoir side has been occluded; partially blocked with mud and the release gates have been only partially operable.