WSP12125

• File Number: 8102
• Description: Arkansas River Hydrology
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 1/1/1997
• Author: USGS
• Title: Description of the Program Changes - 1989-97- and a User Manual for a Transit-Loss Accounting Program Applied to Fountain Creek Between Colorado Springs and the Arkansas River-Colorado
• Water Supply Pro - Doc Type: Report/Study

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Commissioner collects daily diversion data
on the various ditches diverting below the
outfall of the Colorado Springs wastewater-
treatment plant. This requires three trips per
week down the creek to retrieve data from
recorders on the ditches. Colorado Springs
Utilities calls in daily reports of water
returning to the creek at their wastewater-
treatment plant, and at the Fort Carson treat-
ment plant, which obtains its water from
Colorado Springs. These returns are divided
into two components, the first of which is
attributable to Colorado Springs' diversion of
native water and the other of which is attribut-
able to use of non-native trans mountain
water. The Water Commissioner also gathers
daily streamflow data from the six gaging
stations along the creek by accessing the
Satellite Monitoring System via the USGS
computer located in Denver.
The program tracks the different types
of water by assessing a transit loss against
the non-native flow as it progresses down the
creek, taking into account the amount of
native waters being diverted from, or being
added to, the stream by way of tributary
inflows or return flows from water use. Thus,
the Water Commissioner is better able to
determine the amount of native water avail-
able for diversion at each headgate.

SUMMARY

Since April 1989, a FORTRAN computer
program has been used to compute transit losses for
transmountain return flows (TRF's) that are
discharged into Fountain Creek by the City of Colo-
rado Springs (CCS). The transit-loss accounting
program, which was developed as a'result of a study
completed in 1987, enables daily accounting of (I) the
TRF's, (2) the transit losses for the TRF's, and (3) the
native streamflows (NSF's) (nontransmountain water)
in Fountain Creek from the CCS wastewater-treatment
facility (WWTF) downstream to the Arkansas River.
Tn the years following 1989, a number of
changes were made to the accounting program;
however, the program and the changes made to it have
never been documented completely. Therefore, the
U.S. Geological Survey (USGS), in cooperation with
the CCS and the Southeastern Colorado Water Conser-
, vancy District (SECWCD), completed a study to

document the accounting program and prepared a
report that: (I) Describes the computational steps and
procedures of the original accounting program;
(2) describes the changes that were made to the
program in 199\-92 and in 1994-95; (3) provides a
user manual; and (4) documents the procedures for
maintaining the accounting program, the auxil iary
programs, and the numerous output files.
Application of the accounting program is based
on a system of 14 subreaches, 16 nodes, and 4 stream
segments. The subreaches are pans of the study reach
having uniform hydraulic and hydrologic characteris-
tics, and the nodes, which delimit the subreaches,
primarily are defined on the basis of location of
streamflow-gaging stations and streamflow diversions
along Fountain Creek. The stream segments are the set
of subreaches between the gaging-station nodes. The
accounting program requires input of the following
data: (I) Daily quantities of TRF and native return
flow discharged into Fountain Creek at the CCS
WWTF; (2) daily mean discharge at each of the
gaging stations along Fountain Creek; and (3) daily
mean discharge at each diversion operating along
Fountain Creek.
Tn computing the estimated quantities of TRF in
Fountain Creek and the associated transit losses, the
accounting program uses two sets of computations.
The first set of computations is made between any two
adjacent gaging stations (stream-segment computa-
tions); these computations estimate the loss or gain in
NSF between the two adjacent gaging stations. The
second set of computations is made between any two
adjacent nodes (subreach computations); the actual
transit-loss computations are made in the subreach
computations, using the result from the stream-
segment computations. The stream-segment computa-
tions are completed for a stream segment, then the
subreach computations are completed for each
subreach in the stream segment. When the subreach
computations are completed for all subreaches in a
stream segment, the stream-segment computations are
repeated for the next stream segment, followed again
by subreach computations; the process continues until
computations are completed downSlI:eam through
subreach 14.
Use of the accounting program is highly depen-
dent on operation of a gaging-station network on
Fountain Creek. The network originally consisted of
fi ve gaging stations and was expanded to six stations
in 1995. Each station is equipped with a

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SUMMARY 37