PUB00094

• Year: 1998
• Title: Denver Basin and South Platte River Basin Technical Study: Technical Addendum 1 and 2
• Author: Special Water Committee
• Description: Technical addendums for the report
• Publications - Doc Type: Tech Report

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Chapter 1: South Platte Basin Inventory

March 21.1998
Page 1-13

assuming typical monthly CBT delivery patterns and stream depletion factors.
The resulting monthly pattern was then added to the Kersey gage flows for water
years 1950, 1951 and 1952.

Chances In District 2 Diversions.

For the period of October through March, it was assumed that changes in
flow at Henderson and from the Cache La Poudre, Big Thompson and St. Vrain
basins would be transmitted completely to the Kersey gage. For the period of
April through September, it was assumed that a portion of the flow increases
would be diverted by the irrigation ditches on the South Platte between
Henderson and Kersey, The maximum demand of these ditches at Henderson
was assumed to be 550 cfs based on previous call analyses done by Denver
Water, Spronk and Hydrosphere, Any flow increase at Henderson in excess of
this intervening irrigation demand was assumed to arrive at the Kersey gage,

Estimated future flows for the Kersey gage are shown in Table 1-15 and Figure

1-15.

1.1.5 Reusable Flows

Reusable flows from the metro Denver area were estimated only for the
Henderson gage since most reusable return flows are generated at the Metro
Wastewater Reclamation District plant or at downstream locations, All metro Denver
area reusable flows are assumed to accrue to the river at the Henderson gage even
though a small portion of these reusable flows would actually occur slightly
downstream. Reusable return flows were estimated for both existing and future
conditions. Estimates were generated as part of the MWSI project through review of
existing and future water supply system operations for Denver Water, Aurora,
Westminster, Arvada, Thornton, major Douglas and Arapaho County water districts,
Broomfield, Northglenn, Englewood and South Adams County Water & Sanitation
District. Reusable flows are discussed in more detail in Chapter 3, Estimates of
existing and future reusable effluent are shown in Table 1-16 and Figure 1-16. The
second graph in Figure 1-16 shows remaining reusable flows compared to total stream
flows Henderson after accounting for reusable flows utilized in existing and future reuse
plans,

Additional reusable flows accruing to the river at the Kersey gage and not
accounted for at the Henderson gage as discussed above consist of Windy Gap return
flows plus net reusable credits resulting from irrigation rights changed to municipal uses
in the St. Vrain, Big Thompson and Cache La Poudre basins, Currently there is
relatively little Windy Gap water being used. The net reusable credits from Windy Gap
use and changed irrigation rights is estimated to be approximately 5,000 acre-feet per

Hydrosphere Resource Consu~ants, 1002 Walnut Su~e 200. Boulder. CO 80302