It’s official: Irene and Lee flooding set all-time records

PHOTOGRAPHER: Lee Coleman

Tropical Storm Irene, which drenched the Capital Region in late August, set 55 high-water records on streams, creeks and rivers in eastern New York state, including the Schoharie Creek and Mohawk River.

The tropical storm that hit the region late on Aug. 27 and continued throughout Aug. 28 caused millions of dollars in flood damage in Schoharie, Schenectady, Montgomery and Washington counties.

“There were 55 peaks of record,” said Gerald Butch, a hydrologist with the U.S. Geological Survey.

He said Irene set records in the Capital Region while Tropical Storm Lee, which swept through the state a week later, set records along the Susquehanna River and its tributaries.

The U.S. Geological Survey maintains and manages stream gauges in New York state and reports water levels before, during and after major rains as from Tropical Storm Irene. The information is used by the National Weather Service, the Federal Emergency Management Agency and others to alert people to flooding and the potential for flooding.

“Our mission is to collect the data and provide damage assessments,” Butch said.

He said the water ran so high and fast on the Schoharie Creek on Aug. 28 and 29 that two of the USGS river gauges — at Prattsville and just below the Gilboa dam — were destroyed or badly damaged.

“In both cases, we put in temporary gauges for when [Tropical Storm] Lee came through,” Butch said. At both these locations, water level records were set.

The USGS is putting in new permanent gauges at Prattsville and Gilboa and placing them so they won’t be as likely to be damaged by high waters.

Examples of the records could be found at the gauge at the Schoharie Creek Reservoir that reached 1,137.73 feet above sea level after Irene came through, surpassing the old record of 1,136 feet set in January 1996.

At the gauge on the Schoharie Creek at Burtonsville, near the borders of Schoharie, Montgomery and Schenectady counties, a record creek level of 15.3 feet was recorded, surpassing the old mark of 12.08 feet set on Jan. 20, 1996, according to preliminary records. Some of these readings are estimates because the gauges were damaged during the storm.

Butch said the USGS is still compiling its final records for Irene and Lee.

The USGS uses a cubic-feet-per-second stream flow measure in its reporting. For example, the Schoharie Creek at Gilboa had a peak discharge of approximately 108,000 cubic feet per second on Aug. 28, but this was an estimate because the gauge was damaged during the storm.

Butch said the USGS is still waiting for money from the federal government to repair and replace river gauges. However, federal cutbacks won’t affect stream gauges on the Schoharie Creek or any other gauges in the Capital Region. Some gauges in other parts of the state, including Essex and Washington counties, may be deactivated, however.

U.S. Sen. Charles Schumer, D-New York, said this week that he is opposed to the USGS switching off more than 30 stream gauges across the state.

“The flood gauges, located in New York’s Southern Tier, Hudson River, and Champlain Valley, are frequently used to warn residents and business owners in low-lying areas of potential flooding and help communities throughout the state plan for evacuations and flood responses,” Schumer said in a statement.

The USGS said the record levels of water as the result of Tropical Storm Irene’s rainfall exceeded anything recorded previously at these locations, including major floods in 1987 and 1996.

“Some of these stream gauges have been in place for 30 to 101 years,” reads a USGS statement.

Britt Westergard, a hydrologist with the National Weather Service in Albany, said the Schoharie Creek and Mohawk River received much of the flooding, but the Hudson River was also impacted in the Albany area. She said a storm surge and winds from Irene actually pushed water up the Hudson from the south.

This unusual event was recorded early in the storm. Later on Aug. 28, water flowing in from the Mohawk and Hoosic rivers brought the Hudson to much higher than normal levels. No records were set during this event on the Hudson, however, according to preliminary results.

Westergard said records were also set on rivers and streams in Washington County, as well as in Vermont.

The Mohawk River in the Schenectady area went over its banks in places, doing considerable damage, but did not set all-time records. The Mohawk and the Hudson in the Capital Region were both just below the 100-year-flood level.

Hydrologists don’t like to refer to flooding events as a 100-year flood or a 500-year flood. They would rather describe a 100-year flood as a high water event having a one percent chance of happening in any year. This is a way of describing the probability that a given flood exceeded 100 years of water volume records.