30-81 bridge, resulted in a stage of greater than
Table 5. Maximum annual gage
heights associated with ice at the
12.5 ft at the gage, based on high-water marks.
USGS gage on the Loup River at
Local residents described the 1993 event as being
Columbus (period of record 1934
the worst in memory, with a local farm imple-
1979, flood stage 11 ft).
ment dealer noting that the high-water marks on
his building were 4.55 ft higher than during the
Ice-related annual
August 1966 flood, which had a stage of 14.42 ft
Date
maximum stage (ft)
recorded at the USGS gage. High-water marks set
5 March 1936
6.57
by Corps personnel indicated that the stages pro-
26 February 1958
7.53
duced by the ice jam at Columbus were equiva-
5 March 1959
6.18
lent to those that might be expected from an open-
17 February 1961
6.38
16 February 1963
6.04
water event of about 200,000 cfs (USAED, Omaha
21 March 1969
11.2
1993).
3 January 1970
8.0
Ice jams which form on the Platte River be-
20 February 1971
9.3
tween the Burlington Northern Railroad bridge
20 January 1973
7.4
and the tailrace of the Loup River Power Canal
10 January 1974
6.7
11 January 1975
7.46
(Fig. 3) can also affect Loup River stages at Co-
3 January 1976
8.58
lumbus and cause lowland flooding along the
24 February 1977
6.36
Loup and Platte Rivers. Jams are known to have
15 March 1978
8.87
formed in this area in March 1978, March 1979,
7 March 1993
>12.5
February 1982 and late November 1993. The jam
of February 1971, which extended for five miles
lumbus (upstream from the gage), caused over-
up the Loup River, probably also formed in this
bank flooding. No other more specific informa-
area.
tion regarding jam formation or extent was given.
On 30 November 1993, a freeze-up ice jam
The flood stage at the Columbus gage is con-
formed upstream from the Burlington Northern
sidered by the USGS to be 11 ft. The maximum
Railroad bridge (Fig. 3) following a sudden drop
open-water gage height of record was 14.42 ft on
in temperature beginning about 22 November (Fig.
14 August 1966. Prior to 1993 the peak ice-related
4b). The sudden drop in discharge through both
the river and the canal coincident with low tem-
stage at the Columbus USGS gage was 11.2 ft on
peratures is indicative of significant frazil ice for-
21 March 1969, with an average daily discharge of
mation and blockage upstream. The jam extend-
about 16,500 cfs. This ice jam resulted in extensive
ed upstream to the water plant on the north bank
flooding along the route of the present Highway
of the Loup River. Lowland flooding was experi-
81 and the area between the Loup and Platte Riv-
enced on both sides of the river. With rising tem-
ers. The Columbus Daily Telegram reported that the
peratures the jam eventually went out on its own.
jam began forming east of the Highway 81 bridge
Small ice accumulations typical of ice breakup
at about 6:30 p.m. on Tuesday, 17 March, and even-
and movement were evident on the Loup River
tually extended about one-half mile upstream and
upstream from the jam area. It is probable that the
downstream of the bridge. Within two hours wa-
ter levels had risen enough to begin overbank
Loup River was the primary source of ice which
formed this jam.
flooding. According to newspaper reports, blast-
On 14 March 1979, an ice jam formed upstream
ing was done in the vicinity of the Highway 81
bridge. The blasting was eventually successful in
from the Union Pacific Railroad bridge (Fig. 3).
This jam extended about one-half mile above the
removing the jam, which went out about 7 p.m.
bridge and caused lowland flooding. The jam
on 21 March 1969.
eventually failed and moved downstream, rejam-
According to Nebraska Civil Defense records
ming downstream from the Highway 81 bridge.
(1971), the ice jam that occurred in 1971 formed
Backwater from the jam reached bank level at the
about five miles east of Columbus and extended
bridge before the jam failed on 15 March 1979.
for three miles. The jam flooded low-lying areas
southeast of Columbus. Blasting was initially un-
Site 2. Platte River:
successful, but it finally caused the release of the
Highway 79 at North Bend
jam on 24 February 1971.
The Platte River in the vicinity of Highway 79
The ice jam of 710 March 1993, which extend-
at North Bend was also identified as a site of
ed a short distance upstream from the Highway
9
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