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

Chapter 1: South Platte Basin Inventory

March 21.1998
Page 1-10

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upstream municipal water rights, an analysis of this effect was beyond the scope of this
study. For the purposes of this study it was assumed that estimated future flow
increases due to metro area RIS and L1RF would be fully included in the Denver and
Henderson gage flows,

Increased Future Wastewater Flows From Tributaries.

Denver's PACSM model uses historical gage data to simulate inflows from Plum
Creek, Cherry Creek, Bear Creek and Clear Creek to the South Platte. However, it
likely that future flows from Cherry Creek, Plum Creek and Clear Creek will increase
due to increases in wastewater discharges.

At Near Term demand levels, Douglas County water demands will probably
exceed 100,000 acre-feet per year, with most of this supply coming from nontributary
groundwater. As a result wastewater flows in the Cherry Creek and Plum Creek basins
will increase significantly. While some of this wastewater is likely to be reused through
augmentation plans and direct reuse, a net increase in wastewater flows is projected, in
both the Cherry Creek and Plum Creek basins. To estimate this net increase in
wastewater flow, future Douglas County water demands met by nontributary
groundwater, resulting wastewater flows and associated augmentation/reuse plans
were estimated based on current County projections (Mulhern, 1995), The net increase
in wastewater flows derived from nontributary groundwater sources was calculated
taking into account average monthly municipal delivery and wastewater production
patterns, augmentation plans and direct reuse plans. The resulting net increase in
wastewater ranged from 1 cfs to 20 cfs and averaged 5,700 acre-feet per year. These
flows were added to Denver's modeled flows at the Chatfield, Denver and Henderson
gages.

Flows from Clear Creek into the South Platte have increased since 1990 by
approximately 15 cfs due to wastewater discharges from the Coors/Golden plant no
longer being diverted by the Croke Canal. These flow increases are not reflected in
Denver's modeled Henderson gage flows. This increased Clear Creek inflow generally
affects flows at the Henderson gage during all months except August through October,
when intervening irrigation rights on lower Clear Creek divert most of this water. It was
assumed for the purposes of this study that these wastewater flows would increase
average flows at the Henderson gage by 15 cfs during November though July,
Denver's modeled flows at Henderson were adjusted accordingly,

Increased flows from Bear Creek compared to historical gage records were
assumed to be negligible,

Junior South Platte Water Riahts,

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