FLOOD01774

• County: Otero
• Community: La Junta
• Title: Analysis of Hydrologic Factors that Affect Grond-Water Levels in the Arkansas River Alluvial Aquifer near La Junta Colorado 1959-99
• Date: 1/1/2000
• Prepared For: La Junta
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

Table 5. Flow-duration statistics for the Fort Lyon Canal and the Arkansas River at La Junta

[ft3/s, cubic feet per second]
Flow value, Fort Lyon Canal Flow value, Arkansas River at La Junta
(inft3/s) (in ft3/s)
Percentage of
record flow 1961l-1980 1981-1997 1961l-1980 1981-1997
was exceeded
99 0.50 0.09 4.63 20.38
98 2.59 0.18 5.80 24.99
95 55.95 0.44 8.61 33.52
90 97.60 0.88 12.90 44.12
85 130.74 142.00 16.34 53.60
80 152.38 160.52 19.74 63.30
75 160.85 172.39 23.21 73.54
70 169.31 184.26 26.84 83.97
65 177.77 196.12 30.86 94.51
60 186.23 235.Q7 35.05 105.10
55 194.69 288.65 40.08 118.09
50 212.62 345.23 47.08 133.17
45 246.48 408.79 55.94 148.26
40 281.42 476.45 66.21 178.33
35 318.84 557.77 81.55 215.44
30 359.42 635.17 103.07 263.11
2S 4\5.64 705.55 \40.85 324.50
20 481.53 775.93 203.22 404.29
15 583.61 866.86 310 .97 512.36
10 701.39 977.09 451.43 683.10
5 847.30 1087.31 605.25 1283.85
2 1035.61 1387.67 930.43 2807.05
1098.38 1642.28 1714.47 3992.77

indicates that flow in the river experienced a high
period in the 1980's similar to the canal. However, the
high in the river is not as pronounced as the high in the
canal, indicating that most of the relatively large
amounts of water in the river were diverted to the
canal. After 1989, flow in the river, unlike diversions
to the canal, remained above the long-term mean and,
generally, continued to increase.

The flow-duration statistics for the Arkansas
River listed in table 5 also are similar to those for the
Fort Lyon Canal. The tendency for flows to be greater
in the second period is more pronounced for the
Arkansas River; second period flows often exceed first
period flows by a factor of 2 and sometimes by a
factor of 3. For example, flow in the Arkansas River
was greater than about 133 cubic feet per second for
50 percent of the second period; in the first period the

50 percent exceedance flow was about 47 cubic feet
per second.

Surface-Water Applications

As indicated in the Introduction, there is a large
diversion of water from the Arkansas River into the
Fort Lyon Canal a few miles west of La Junta. The
Fort Lyon Canal often carries more water than the
Arkansas River and is a contributor to the fact that
the median flow for the Arkansas River at La JUllta,
which has a contributing drainage area of about
12,000 square miles, is only about 60 cubic feet per
second.
The Fort Lyon Canal conveys water to many
areas east of the study area, and only part of the water
diverted to the canal is used in the study area. Local

HYDROLOGIC FACTORS THAT AFFECT GROUND-WATER LEVEI.5 19