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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13

Inspection of the double-mass diagrams of the Arkansas River at

Las Animas vs, Adjusted Canon City Flows (set 4) shows that the

decline in the inflows to John Martin Reservoir began immediately

after adoption of the Compact. During the entire post-compact

period, the relationship of John Martin Reservoir inflows to

Adjusted Canon City Flows has remained relatively constant. Noted

exceptions are the diagrams of winter flows (November-March), The

slopes of these curves for the post-compact period have declined

starting in about 1974 in relation to the 1949-1973 period,

Diagrams of Usable Stateline Flows vs, Index Flows were also pre-

pared. The Index flows are defined for purposes of this analysis

as the sum of the Purgatoire River at Las Animas and the Adjusted

Canon City flows, This provides another indication of the avail-

able water supply in the basin, combining the Arkansas and

Purgatoire River flows, The Purgatoire River has historically

contributed approximately 15% of the combined flow. The diagrams

of Usable Stateline Flow vs. Index Flows (set 5) indicate the same

trends as do the adjusted Canon City diagrams, The Purgatoire

River flows have declined considerably during the post-compact

period, Because this decline is incorporated into the index flow,

the change of Usable Stateline Flows in relation to the Index Flow

is less than the the change in relation to the Adjusted Canon City

flows,

.