WSP06720

• File Number: 8111.831
• Description: Arkansas River Compact Administration - Article VIII Investigations
• Basin: Arkansas
• Date: 1/1/1985
• Author: David Pope
• Title: Report to the ARCA regarding Article VIII ‎(H)‎ Investigation of Alleged Violations of the Arkansas River Compact
• Water Supply Pro - Doc Type: Publication

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19

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The increase in flows of the Arkansas Riv r at Las Animas for the

period of 1974-1984 may be the result of ransmountain return

flows which also increased during this per'od. These return flows

may be masking depletions of flow above John Martin Reservoir.

which otherwise would have been apparent if the transmountain re-

turn flows were not available. It is also likely that some deple-

tions to usable stateline flows have been masked by the existence

of transmountain return flows in the river.

The continued existence of these return flows in the Arkansas

River is not guaranteed since users of transmountain water are

entitled under Colorado water law to reuse and completely consume

transmountain diversions, If transmountain return flows are not

maintained, the future available supply for downstream users on

the Arkansas River would decrease, This decrease in supply may
reduce the quantities available for conservation storage in John

Martin Reservoir and usable stateline flows.

~QN~1Q~IQN~
The data and mass diagrams indicate that post-compact depletions
of usable stateline flows have occurred as evidenced by changes in
slope on the post-compact portions of the curves, The breaks in

slope generally occur in 1949 and 1974. Analyses of the slopes of

the curves indicate that usable stateline flows have been depleted

by approximately 40,000 to 50,000 acre-feet per year for the