WSP03745

• File Number: 8111.815
• Description: Arkansas River Compact Administration
• Basin: Arkansas
• Date: 4/1/1990
• Author: UCACOE
• Title: Drought Contingency Plan - John Martin and Trinidad Lake - Appendix D
• Water Supply Pro - Doc Type: Publication

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drought by June 1934. This drought reached its greatest severity in March 1935
with PDSI of -6.41. The severe to extreme drought extended from June 1934
through 1937. Precipitation for the seven year period was approximately 87
percent of normal. The annual river flow at the present John Martin Reservoir
site for the seven year period was approximately 38 percent of normal. The
annual river flow at the present Trinidad Lake site for the seven year period
was approximately 80 percent of normal. The 1934 Purgatoire River flow at the
Trinidad Lake site was 43 percent of normal and was the lowest for the seven year
period. Plate 3-2spows the PDSI for this period.

d. Drought of 1939-1940. This drought started off as a mild to moderate
drought and intensified to a severe drought. The severe drought extended from
October 1939 to December 1939 and leveled off to a mild to moderate drought
through March 1940. This drought reached its greatest severity in October 1939
with a PDSI of -3.87. The annual rainfall for 1939 was approximately 69 percent
of normal. The annual river flow at the John Martin Reservoir site was five
percent of normal during the two year period. At the Trinidad Lake site, the
annual inflow for the two year period was 60 percent of normal. Plate 3-3 shows
the PDSI for this period.

e. Drought of 1950-1956. A moderate to extreme drought occurred during
this period. This drought reached its greatest severity in October 1956 with
a PDSI of -6.46. The lowest annual rainfall for this period of record was 1956
with 10.88 inches. The precipitation for the seven year period was 85 percent
of normal. The annual inflow into John Martin Reservoir during this six year
period was approximately 50 percent of normal, except for 1955. The annual flow
at the Trinidad Lake site was approximately 56 percent of normal for the six year
period. Plate 3-4 shows the PDSI for this period.

f. Drought of 1963-1964. This drought intensified to an extreme drought
by May 1963 and extended through December 1963. This drought reached its
greatest severity in July 1963 with a PDSI of -6.51. Practically all of this
period was in the severe drought level, with precipitation at 81 percent of
normal. The annual inflow into John Martin Reservoir was 31 percent of normal
during this two year period. At the Trinidad Lake site the annual flow was 44
percent of normal. Plate 3-5 shows the PDSI for this period.

g. Drought of 1974-1978. The annual inflow into John Martin Reservoir was
41 percent of normal during this period. At the Trinidad Lake site, the annual
inflow was 35 percent of normal. This drought started as mild to moderate and
intensified to a severe drought. This drought reached its greatest severity in
July 1976 with a PDSI of -3.70. The precipitation during the period was 87
percent of normal. The low annual inflow was partially accounted for by below
average snowmelt runoff during the period. Plate 3-6 shows the PDSI for this
period.

h. Other Droughts. There were other droughts which have occurred in the
Basin, only the most severe were described above. The droughts, not described,
were generally moderate to mild and lasted only for a few months to a year at
a time. The PDSI for the period of record (1895 to 1987) is shown on Plate 3-
7. The observed annual inflow and outflow for John Martin Reservoir and Trinidad
Lake are shown on Plates 3-8 through 3-11. As seen on Plates 3-8 through 3-11,

3-3