WSP08775

• File Number: 8056
• Description: Drought Preparedness
• State: CO
• Basin: Statewide
• Date: 1/1/1979
• Author: USGS
• Title: Hydrologic and Human aspects of the 1976-77 Drought
• Water Supply Pro - Doc Type: Report/Study

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CHRONOLOGY OF THE 1976-77 DROUGHT

73

red. Rains carried by the trade winds provided
adequate water between February and June
1952 except on Molokai where precipitation
was less than half of average. The late
summer was dry and so was the early winter,
Pastures on Molokai and Maui were brown, and
truck crops wilted. Some wells ran dry or
became brackish, and drinking water was being
trucked from higher elevations to the Kona
area, on the west coast of Hawaii, January
1953 was very dry with Maui receiving only 10
percent of normal rainfall. Ground water was
pumped into the elaborate ditch system on
Maui to provide flows near a quarter of its
capacity. Thunderstorms in mid-February
brought some relief, but the drought continued
throughout the sum mer of 1953.
At Waipahu, Oahu, near Pearl Harbor west
of Honolulu, monthly rainfall was well below
normal for 18 of the 21 months from January
1952 through September 1953, This record
indicates the lack of the usual number of or
substantial Kona storms which are the wide-
spread storms that usually occur during the
winter. The deficient rainfall from the trade
winds during the rest of the year is indicated
by the record at Luakaha in the mountains
back of Honolulu where rainfall was below
normal in 12 of the same 21 months and in 6 of
the last 7 months. Rains in October and
November 1953 ended the drought. Previous
record low rainfall had been in 1921 on Kauai,
in 1933 on Oahu, and in 1917 on Maui and
Hawaii,
What was called a dry spell by some and a
drought by others occurred in the summer of
1971. Maui was particularly hit hard, and less
severe conditions existed on Hawaii, Molokai,
Oahu, and Kauai. The major cause was the
absence of normal rainfall from the trade
winds that bring moisture to the higher eleva-
tions on the windward sides of the islands.
There are no ground-water sources on East
Maui to supplement a shortage in the streams;
therefore, when the number of rainy days and
the amount of rainfall were reduced signifi-
cantly, drought conditions existed. Irrigation
and domestic uses were sharply curtailed on
Maui and Hawaii, water was trucked to fami-
lies on Molokai and to irrigate macadamia nuts
on Hawaii, temporary pumps were installed to
raise water from a low elevation reservoir into
a higher level ditch system on Maui, and
planting of sugar cane was delayed until sig-

nificant rains occurred. Rains ended the
drought in September 1971.
The May through August 1971 precipitation
at Waikamoi Dam on East Maui was the lowest
since records began in 1911 and was 30 percent
of normal as compared to 40 percent in 1953,
The 4-month rainfalls at other Maui sites were
in the range of 19 to 52 percent of normal.

Precipitation and Runoff

Precipitation for 1975 at the four index
sta tions on the four larger islands ranged from
75 to 107 percent of normal. The below
normal trend started about March 1975 with
the bulk of the deficiency occurring during the
summer and fall. Even the 107 percent of
normal at Honolulu was caused primarily by
almost four times the normal rainfall in
November whereas 10 of 12 months in 1975
were below normal.
Rainfall was below normal during 11 of the
12 months in 1976 at Honolulu, Oahu and
Kahului, Maui. Only February was above
normal. Precipitation was deficient for 9 of
the 12 months at Hilo, Hawaii and for 8 of
them at Lihue, Kauai. At Honolulu, only 15
percent of the normal rainfall occurred during
the period September through December 1976,
and December with only 0.06 in. was the driest
December in the 100-year period of record,
Below normal precipitation continued into
March 1977, then above normal precipitation
in April on all the islands and in May and June
on Kauai and Oahu relieved the drought con-
ditions to some extent. But the pattern of
below normal rainfall was reestablished in July
and continued through December.
Runoff during the last 8 months of 1975
was below normal on the islands of Hawaii and
Kauai and was normal for most of that time on
Maui and Oahu. Deficient runoff conditions
continued into 1976 and became serious enough
by August 1976 to be considered a drought
which persisted to March 1977. Runoff in-
creased in April and in May on Kauai and Oahu
in response to the above normal precipitation,
and was again generally deficient from July
through December 1977.

Ground-water Conditions

Water levels in five observation wells de-
clined to record low levels. Three of the mini-