WSP12671

• File Number: 8146.600.30.A
• Description: Purgatoire River Study
• State: CO
• Basin: Arkansas
• Date: 1/24/2007
• Author: USDOI/SGS Lisa D Miller
• Title: Losses and Gains for Eight Unlined Canals Along the Purgatoire River Near Trindad, Colorado 2000 - 2004
• Water Supply Pro - Doc Type: Publication

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Canal Losses and Gains 11

Table 2. Annual total acre-feet and total days used for eight Purgatoire River Water Conservancy District canals, irrigation years
2000-2004 (as reported by Colorado Division 7 Water Resources, State Engineers Dffice).

[NA, not applicable]
Irrigation year: 2000 Irrigation year: 2001 Irrigaltion year: 2002 Irrigation year: 2003 Irrigation year: 2004
Canal Annual Total Annual Total Annual Total Annual Total Annual Total
name total days total days total days total days total days
acre-feet used acre-feet used acre..feet used acre-feet used acre-feet used
Baca 1,279.08 166 1,381.49 178 509.38 79 1,177.90 152 993.55 133
Chilili 1,326.78 111 1,273.11 105 23.88 4 1,380.30 114 618.08 55
EI Mom 538.10 106 473.46 126 58.69 18 630.93 143 366.59 78
Hoehne 5,039.72 120 5,345.53 138 2,795.80 80 5,209.74 127 5,215.63 139
John Flood 8,822.41 158 6,946.83 174 563.10 63 5,149.05 167 5,612.91 191
Model 10,974.01 108 7,544.00 119 1,660.92 29 2,275.95 29 10,574.08 120
Picketwire 10,021.00 186 6,011.59 165 649.28 65 4,675.29 145 5,387.27 127
Enlarged Southside 22,227.16 119 12.292.82 74 148.13 5 6,601.78 61 15,411.40 97
Total 60,228.26 NA 41,268.83 NA 6,409.18 NA 27,100.94 NA 44,179.51 NA

Canal, and each Baca turnout is equipped with a Parshall
flume. Results from the Baca Canal loss and gain measure-
ments are included in this section because, for purposes of
this study, Baca Canal is considered to be a subreach of the
Picketwire Canal that extends from about 1.5 miles to about
3.5 miles downstream from the Picketwire Canal headgate
(PWHG) (fig. 1 and fig. 4). Losses and gains for selected
subreaches of Picketwire Canal are shown in table 3, and
losses and gains for Baca Canal are shown in table 4.
Loss and gain measurements were made at numerous
locations (fig. 4) along Picketwire/Baca Canal on August 2,
2000, May 16,2001, June 18,2003, and June 10,2004. Infor-
mation for individual measurements is summarized in table Al
in the Appendix. Figure 5 shows losses and gains along
Picketwire Canal in relation to distance downstream from the
headgate for measurements made on August 2, 2000, May 16,
2001, June 18,2003, and June 1O,20D4.
On August 2, 2000, discharge measurements were
made at main canal and diversion locations from the headgate
(PWHG) to PW26, a distance of about 15.1 miles. Leakage
was observed at three closed diversion gates (table AI). The
total leakage from the three gates was estimated to be about
0.9 ft3/s. A gain of about 1.2 ft3/s (3 percent of the subreach
inflow) was measured along the Baca subreach from BAOl to
BAI0 (table 4). The loss for the entire Picketwire Canal from
PWHG to PW26 was computed to be 3.3 ft3/s, or 7 percent of
the headgate inflow (table 3 and fig. 5).
Discharge measurements were made at main canal and
diversion locations from PWHG to PW27, a distance of about
16.0 miles, on May 16,2001. No leakage was observed at the
diversion gates (table AI). A loss of about 4.6 ft3/s (13 percent
of the subreach inflow) was measured from BAOl to PW02
(tables 3 and 4), a 2.4-mile reach. The loss from PWHG to
PW27 (table 3) was computed to be 9.4 ft3/s, or 23 percent of
the headgate inflow (fig. 5).
Discharge measurements were made at main canal and
diversion locations from PWHG to PW02 on June 18, 2003
(fig. 4). No leakage was observed at the diversion gates

(table AI). The loss from PWHG to PW02, a 3.9-mile reach,
was computed to be 2.0 ft3/s, or 13 percent of the headgate
inflow (fig. 5 and tables 3 and 4).
On June 10, 2004, discharge measurements were made
at main canal and diversion locations from PWHG to PW26
(fig. 4). Minor leakage of less than 0.02 ft3/s was estimated
at three closed diversion gates (table AI). No leakage was
observed at the remaining diversion gates. A loss of about
1.7 ft3.'s (4 percent of the subreach inflow) was measured along
the Baca subreach from BA02 to BAlO (table 4), a 1.9-mile
reach. The loss from PWHG to PW26 was computed to be
4.8 ft3ls, or 12 percent of the headgate inflow (fig. 5 and table 3).
Loss and gain measurements showed that Picketwire
Canal generally loses some flow from the headgate to the
end of the canal (PWHG to PW26) (table 3 and fig. 5),
although some subreaches showed gains in flow during the
2000 and 2004 studies. Losses in the canal appear to decrease
the longer the canal flows. For example, the greatest loss
(9.4 ftJ/s or 23 percent of the headgate inflow) was measured
on May 16,2001, when the canal had only been flowing for
about 10 days before the measurement, whereas the small-
est loss from the headgate to the end ofthe canal (3.3 ft3/s, or
7 pewent of the headgate inflow) was measured on August 2,
2000, when the canal had been flowing for about 107 days
before the measurement (table 3).
Main canal measurements were not made at BAO 1 on
June 18, 2003, and June 10, 2004, and maim canal measure-
ments were not made at BAIO on May 16,2001, and June 18,
2003. As a result, losses and gains from BAOl to BAIO (Baca
subreach) were not computed for the 2001,2003, and 2004
measurements. Losses and gains are shown in table 4 for
reaches from BA01 to PW02 on May 16,2001, from PWHG
to PW02 on June 18, 20D3, and from BA02 to BAIO on
June 10, 2004.
The losses and gains computed along the Baca subreach
on August 2, 2000, and June 10, 2004, are small and are
within the uncertainty of the measurements (:t5 to 8 percent).
The measurement made on June 18,2003, also may indicate