The Passaic Flood of 1903 | Page 2

channel of the lower Passaic at full bank carries about
12,000 cubic feet of water per second, but at the height of this flood it
carried about 35,700 cubic feet per second.
The flood period for the entire stream can not be exactly stated, as the
overflow did not occur at the same time in different parts of the basin.
For example, the gage-height records at Dundee dam show that the
flood began to rise on October 8 at 6.30 a. m., and reached a maximum
of 9-1/2 inches over the dam crest at 9 p. m. on October 10. Similarly,
on Beattie's dam at Little Falls the flood began to rise at midnight on
October 7, and reached its maximum at 2 p. m. on October 10, or about
thirty-eight hours after the initial rise, the height of the water being 1.29
inches over the crest of the dam.
The flood rose on the highland tributaries as follows: On Ramapo River
the flood crest passed Hillborn at about 10 a. m. on October 9 and
reached Pompton, at the mouth of the river, shortly after noon of the
same day.
The highest reading recorded on the Geological Survey gage at the
feeder of Morris Canal, in Pompton Plains, was 14.3 feet, at about 6
o'clock on the morning of October 10. As this gage is read only once
daily it is probable that this reading does not represent the height of the
flood crest. Evidence shows that it passed this point on the previous
day. Records of the Newark water department show that the flood on
Pequanac River began to rise at Macopin dam on October 8 at noon,
and rose rapidly to the maximum of 6,000 cubic feet per second at 4 p.
m. on October 10.
No records are available with reference to the rise of flood on Wanaque

River.
Observations made on Pompton Plains on the morning of the 11th
show that Pompton River was well within its banks at that time;
therefore the Ramapo, Wanaque, and Pequanac must have discharged
their flood waters some time previous to this hour. The fact is
important when considered in connection with the height of water in
the main stream at that period. This observation was made only
eighteen hours after the maximum height over Beattie's dam at Little
Falls, and twelve hours after the flood crest passed Dundee dam. The
conditions here outlined illustrate the rapidity with which flood waters
are discharged from the Pompton drainage area, and the deterring effect
of Great Piece Meadows upon the flood.
The rise of the flood on Rockaway River at Old Boonton was almost
coincident with that on Pequanac River at Macopin dam. The
maximum flow occurred fourteen hours later than the maximum on the
Ramapo at Pompton.
The flood crest did not reach Chatham on upper Passaic River until the
morning of October 11, or about twenty-four hours later than the flood
heights in Pompton and Rockaway rivers, and about twelve hours later
than the maximum over Dundee dam.
Adequate reasons for these differences in flood periods between
neighboring points are abundant. They are apparent after a review of
the physiographic conditions described in Water-Supply Paper No. 88.
The flood of 1903 was the immediate result of an enormous rainfall,
and not, as is often the case in north temperate latitudes, the combined
effect of rainfall and the rapid melting of accumulated snows. The
records of weather-observation stations in northern New Jersey and
New York fail to show, throughout their entire observation periods, as
great an amount of precipitation in so short a period. The storm which
was the immediate cause of the flood occurred principally between
October 8 and 11. During that interval rain fell to an average depth of
11.74 inches over the Passaic Basin.

The Passaic Basin is fairly well supplied with storage facilities, which,
under ordinary circumstances, would temper the severity of floods by
holding back a large amount of water. In this case no such effect was
produced, as the reservoirs, lakes, and ponds on the drainage area were
filled, or practically so, at the beginning of the storm, and there was
consequently no available space in which to hold back even an
appreciable part of the run-off water. Over some of the dams in the
highland region a comparatively small amount of water was being
discharged at the beginning of the storm. Therefore, while these storage
basins may have had a certain deterring effect upon the rate of flood
accumulation, they could not, in the end, assist materially in preventing
damages in the lower part of the drainage area.
PRECIPITATION.
The precipitation records for June, July, August, and September are
given below:
Precipitation, in inches, in Passaic Valley and vicinity, June to
September, 1903.
-----------------+--------------+--------------+--------------+------------ |