Table 7. Summary of ice-related flooding at Big Island.
Date
Description
615 March 1949
overbank flow 0.5 to 4 miles upstream from Highway 77 bridge
624 March 1950
possible overflow into Big Island
March 1978
100 evacuated by airboat
1116 March 1979
lowland flooding, jam near BNRR Bridge
22 February 1982
jam three-quarters of a mile downstream from Highway 77 bridge
1418 February 1984
roads flooded, residents evacuated
7 January 1985
evacuations due to ice-related high water
late February-early March 1989
minor ice-related flooding
span (1978) reported ice-related flooding at Big
side of the river, resulting in flooding on High-
Island during the floods of 615 March 1949, when
way 79 and in the Morse Bluff area.
overbank flow was observed between about one-
In February 1982, ice jammed intermittently at
half mile downstream from the Highway 77 bridge
the upstream side of the bridge, and a jam formed
and a point about 4 miles upstream from the
about three-quarters of a mile downstream from
bridge. It is possible that the area was flooded
the bridge. Blasting was considered, but the jam
again on 624 March 1950, although Big Island
failed before blasting could be started. The
was not specifically mentioned by Wehrspan, who
McGinn's Lake and Wolf Lake areas were flood-
reported that "ice jams caused moderate over-
ed. NWS records indicate that lowland flooding
bank flow on the Platte River in the vicinity of
along the south bank also resulted from the Feb-
Fremont, Linwood, Schuyler and North Bend"
ruary 1985 event. Jamming upstream and down-
during this event.
stream from the bridge caused lowland flooding
Big Island was flooded in 1978, and 100 people
in March 1993.
were evacuated by airboat, according to the Oma-
ha World-Herald. No other details about the ice
Site 3. Platte River:
jam causing this flood were given, although it is
Big Island at Fremont
probable that the ice jams at Mercer and down-
Big Island is located along the north bank of
stream, which flooded the Valley area, contribut-
the Platte River to the southwest of Fremont (Fig.
ed to elevated water levels at Big Island. In March
5) and includes several residential developments
1979, Nebraska Civil Defense records reported
built around lakes. There is some anecdotal evi-
lowland flooding in the Big Island area due to ice
dence that an ice jam occurs in the reach along Big
movement and jamming at the Burlington North-
Island, with the jam toe about 1 mile upstream
ern Railroad bridge.
from the Highway 77 bridge.* According to local
An ice jam formed about three-quarters of a
residents, ice blocks which pile up at the Burling-
mile downstream from the Highway 77 bridge on
ton Northern Railroad bridge can also raise the
22 February 1982. This jam raised water levels in
water level sufficiently to cause backwater to flow
the Big Island area, prompting some evacuations.
into the Big Island area. In most cases the back-
Nebraska Civil Defense records indicate that the
water is probably formed by jams which form in
jam moved out by itself late in the afternoon but
several places downstream from Fremont. One
rejammed between the Ford Farm and the High-
recurring jam initiation location is about a half
way 64 bridge in the same location as the major
mile downstream from the Highway 77 bridge,
jam of 1978.
and another is in the vicinity of Mercer, about 3
The NWS indicated that minor ice-related
3.5 miles downstream from the Burlington North-
flooding was affecting Big Island on 14 February
ern Railroad bridge. Known ice-jam-related flood-
1984. By the next day, roads in the area were flood-
ing events are summarized in Table 7.
ed, and on 16 February 1984, a number of resi-
In a review of ice-related flooding within the
dents were evacuated from the area. The jam was
PapioMissouri Natural Resources District, Wehr-
not described, but it appears to have extended at
least as far as Ridge Road from an unknown point
* Marlin Petermann, personal communication.
downstream. The jam was observed from the air
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