WSP09785

• File Number: 8142.600.30.A
• Description: Trinidad Project - Studies - Other Studies - Purgatoire river transit loss study
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 1/1/1993
• Author: USGS
• Title: Evaluation of Streamflow Traveltime and Streamflow Gains and Losses Along the Lower Purgatoire River Southeastern Colorado 1984-1992
• Water Supply Pro - Doc Type: Report/Study

0812

establishing in-channel streamflow losses between the
Ninemile Canal [site Q3A (fig. 1)] and the Highland
Canal, a distance of about 32 river miles, that varied
from streamflow losses of 3 ft3 Is in winter to 8 ft3 Is
during summer.
A study by the Bureau of Reclamation (1964b)
reported that "it is generally recognized that natural
chaune110sses of the Purgatoire River are consider-
able" (p. 71) in certain reaches, and "the normal flow
of the Purgatoire River at Trinidad has very little
chance of reaching Alfalfa" (p. 72). The study
also reported that "fairly reliable loss rates can be
determined for 105 river miles" (p. 79) on water
transported between Alfalfa and the Highland Canal.
Channel losses were not estimated for river reaches
upstream from Alfalfa or downstream from the
Highland Canal because of the difficulty in estimating
diversions and return flows in these irrigated reaches
of the lower Purgatoire River. Generally, there were
few records of tributary inflow available for tl)e
analysis periods used in this study.
A more recent study (Colorado Department
of Natural Resources, 1975) attempted to determine
the amount of streamflow needed for downstream
deliveries to satisfy the senior water rights of the
Highland Irrigation Company, operator of the last
irrigation canal diverting from the lower Purgatoire
River. The study was conducted during summer, and
the riverbed was generally dry. Streamflow in the
Purgatoire River was regulated for several days using
bypasses at the Enlarged Southside Ditch, a large
canal near Trinidad that can divert a large percentage
of the available streamflow. Streamflow measure-
ments were made to determine conveyance losses
from Alfalfa to the Highland Canal. Following
several incremental increases to streamflow near
Trinidad, streamflow finally arrived at the Highland
Canal more than 16 days after the upstream releases
started. During this study, streamflow losses of
20 percent to more than 80 percent were indicated
in some river reaches (Colorado Department of
Natural Resources, 1975).
Another analysis of data from the study
described in the previous paragraph indicated that a
traveltime of approximately 5 days for water to flow
about 110 mi from Alfalfa to the Highland Canal was
more reasonable than the 16 days reported in the study
by the State (David E. Fleming, David E. Fleming

Company, written comrnun., 1975). Fleming
concluded that the 35 ft3 Is being supplied downstream
from Alfalfa in the first 10 days of the conveyance test
,was insufficient to result in measurable streamflow
!at the Highland Canal. Streamflow losses of about
i37 ft3/s were reported by Fleming along the 110 mi
lof river between Alfalfa and the Highland Canal.
Qazi and Krason (1976) reviewed and
analyzed many of the previous studies in the basin
land concluded that insufficient data were available
,to quantify streamflow losses along the lower
iPurgatoire River. Qazi and Krason (1976) concluded
!that (1) the irrigation season generally was a period of
'streamflow loss and the nonirrigation season generally
,was a period of streamflow gain in the river reaches
:from Trinidad (site Q1A) to Hoehne (site QIB) and
from Alfalfa (site Q 1 C) to the Ninemile Canal
(site Q3A); and (2) streamflow was observed to
'generally increase in the river reaches from Hoehne
ito Alfalfa and from the Ninemile Canal to the
iLas Animas streamflow-gaging station (site Q4).
i
,

,

I Generalized Study Approach

A compilation of historical streamflow records
. collected by Federal and State agencies along the
,lower Purgatoire River was made for the purposes
of selecting data and time periods that could be used
to estimate streamflow traveltime and streamflow
gains and losses. Streamflow traveltime is the amount
of time it takes for a parcel of water to travel some
i known river distance downstream. Streamflow gains
and losses are the amount of water that is interchanged
between surface- and ground-water systems along the
river and are computed by subtracting all the surface
water leaving a river reach from all the surface water
entering a river reach. The review of available stream-
flow records indicated (1) mainstem streamflow data
along the lower Purgatoire River were available since
1895; (2) tributary streamflow data in the study area
were limited and available for only a few tributaries;
(3) the best continuity of tributary streamflow data was
for 1957-67 and 1984-92; (4) daily mean streamflow
and daily diversion data were available for both of
these time periods; and (5) hourly streamflow data
needed to evaluate streamflow traveltimes were
readily available after 1990.

6 Evaluation of Streamflow Traveltime and Streemflow Galne end Losses along the Lower Purgatoire River,
Southeastern Coloredo, f 984-92