CAP has conducted an analysis of our system and determined the volume of water that can be made available during the 6-week Salt River Siphon outage. The available volume is dependent on:

  • Initial filling depth (and corresponding volume)
  • How far down the canal is drawn during the outage
  • Losses due to evaporation


In preparation for the outage, CAP will fill all pools downstream of the siphon to the top of the canal lining. A pool in the CAP system is defined as the section of canal between check structures or pumping plants and is identified by the downstream check structure or pumping plant. Pools upstream of Brady Pumping Plant will be drawn down to 8 feet and pools downstream of Brady Pumping Plant will be drawn down to 7 feet. The Lower Raw Water Impoundment will be drawn down to 5.5 feet and the Black Mountain Operating Reservoir will be drawn down to 6 feet. Evaporation was assumed to be roughly 7.7% of the initial volume.

The figures below show the volume available in each pool. The first figure shows all turnouts in Segment 4 as orange squares on the diagram. The second figure designates Segments 5 through 10, the Lower Raw Water Impoundment, and the Black Mountain Operating Reservoir. Note that each customer will only be able to take water through their existing turnout or pump as long as the turnout/pump has an intake depth below the water level.

The minimum depths provided reflect minimum depths at the check structures at the downstream end of the pool, but there will be locations upstream of the checks that go below the minimum depth.  If you wish to know the minimum depth at a particular location please contact:

Anna Corrigan
CAP Water Operations Department
acorrigan@cap-az.com
623-869-2629

Note that customers will not be able to access water in any pool downstream of their water intake, as water cannot be moved in the upstream direction.

Salt River Siphon Outage Map of Segment 4
Figure 1
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Salt River Siphon Outage Map of Segment 5
Figure 2
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