Figure 5. Identified recurring ice jam sites on the Platte River between North Bend and Ashland

Table 5. Maximum annual gage heights associated with ice at the USGS gage on the Loup River at Columbus

Table 6. Summary of ice events at North Bend with a stage greater than the flood stage of 8 ft.

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Union Pacific R.R.

Figure 5. Identified recurring ice jam sites on the Platte River between North Bend and Ashland.

ously since 1949. Ice jams have been reported at

recurring ice jams. According to local residents

the gage in 1971, 1972 and 1978. In addition, peak

the jams initiate at a point about 22.5 miles down-

annual stages caused by backwater from down-

stream from the Highway 79 bridge, in the reach

stream ice have occurred at the North Bend gage

upstream from Pole Island (Fig. 5). Ice-jam-relat-

relatively frequently--in 19501953, 1955, 1958

ed flooding occurs primarily in the Morse Bluff

1963, 1970, 1974, 19761977, 19791980, 19821983,

area, but lowland flooding could occur on both

19851986 and 19881989.

sides of the river. Ice jams have also been noted

The flood stage at this gage, 8 ft, has been ex-

upstream from the Highway 79 bridge, but data

ceeded during the period of record by 14 ice-re-

are sketchy. For example, Nebraska Civil Defense

lated events, 11 of which occurred between 1971

records report that an ice jam located about 1.75

and 1989 (Fig. 6, Table 6). Using the difference

miles upstream from the bridge in February 1980

between recorded stage and flood stage as a mea-

resulted in lowland flooding, but no other infor-

sure of severity, it appears there has been a trend

mation about the jam (i.e. location of toe, length,

toward more severe ice events in recent years.

stages) was available. In February 1982, ice jams

However, more detailed information about events

were located both upstream and downstream from

within and outside the period of record, as well as

the bridge. Sandbagging of the levee in the

changes in observers and observation methods,

McGinn's Lake area about four miles west of North

would be required to verify this apparent trend.

Bend was begun when backwater from the jam(s)

In addition, changes in river morphology and

approached within six inches of the top of the

property development patterns may also affect

levee.

stages.

A USGS gaging station is located on the left

The maximum stage recorded at the North

bank of the river just upstream from the Highway

79 bridge. This gage has been operated continu-

Bend gage was 15.55 ft on 19 March 1978, during

10

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