One of the realities of the Sycamore Island Club is that from time to time, the whole place disappears under water. After all, the Island resides in the Potomac River's flood plain. In the great flood of 1936 (river height was 28 feet), the river washed away the large boathouse that contained all the member's canoes, and the club's clubhouse which had just seen years of restoration work done on it.
The current clubhouse, built using steel girders on the lower floor every 10 feet, has survived 7 serious floods since it was built shortly after the catastrophe of 1936.
The following year, in 1937, it survived a 23-foot flood, and 5 years later in 1942, it survived a 27-foot flood! 1955 recorded a 17.6-foot flood and in 1972, Hurricane Agnes drenched the watershed producing a 22-foot flood. In 1985 the clubhouse suffered an 18-foot flood and the freak snowmelt and rain combination in January 1996, produced a flood of 19 feet. Eight months later, a wet week followed by Hurricane Fran culminated in the second flood of 1996 which reached 17.8 feet.
The river's height is estimated to be about 5.5 feet when the water reaches the top of the ferry landing on the Sycamore Island side. The ferry itself becomes difficult to operate above 5 feet and by 6 feet is almost impossible. The ferry's pull-rope can be manually pulled up to clear the water at about 10 feet; after that it must be disconnected. About 10 feet is also estimated to be the height that the water wets the grass floor of the canoe shed. About 16 feet is estimated to be the height the river has to reach before it wets the floor of the clubhouse's lower floor.
An analysis of the data below reveals that, on average, the river floods high enough to threaten the lower floor of the clubhouse once every 7 - 10 years. Also, again on average, the river floods high enough to threaten the lowest canoe rack about once or twice every year! The region's cooler months are also its wettest months, accounting for the preponderence of floods during that time of the year.
Because of the fickleness of the weather, some years see almost no high water while other years experience too much. The trends in the data show there were twice as many serious floods (over 9.5 feet) between 1935 and 1965 than from 1965 to 1995. But for ALL floods (over 6.5 feet), there were almost twice as many floods in the 1970s, 1980s and 1990s as there were in any of the 4 decades before them. The last 30 years of the 20th century saw unprecedented suburban growth around the Island and significant suburbanization of hundreds of square miles of land upstream on both sides of the river. (To see this area before much of it was developed, view the 1937 aerial photo
.) It would appear that development is reducing the land's ability to retain water, producing more flash flooding on a routine basis. So far, any trend toward a greater number of larger floods is not yet statistically significant. 1998 was considered an El Nino year (wet in our region) while 1999 and 2000 were La Nina years (dry in our region).
Below is the statistical record of peak river stage height (in feet) at the Little Falls gauge since 1931 (these are only the peaks above 6 feet). For more information or other river statistics, visit the USGS web site at Little Falls
. (1999 and 2000 data not currently available.)