Relations of Main-Stem Reservoir Operations and Specific Conductance in the Lower Arkansas River

• Description: Relations of Main-Stem Reservoir Operations and Specific Conductance in the Lower Arkansas River
• State: CO
• Author: Lewis, Michael; Brendle, Daniel
• Title: Relations of Main-Stem Reservoir Operations and Specific Conductance in the Lower Arkansas River
• Water Supply Pro - Doc Type: Report/Study

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19b4 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994
Figure 7. Specific conductance at station 07096000 (Arkansas River at Canon City), 1964 -94.
Boxplots of monthly specific- conductance data for
1964 -74 and 1975 -94 indicate that, after 1974,
the median specific conductance tended to decrease
during most low -flow months and increase during
late summer (fig. 8), thus correlating well with the
monthly streamflow trends. Specific conductance
decreased significantly in January, February,
and March (table 3), which are months having
low streamflow. Although specific conductance
tended to increase during July through September
(fig. 8), the differences were not statistically
significant (table 3).
The significant increase in streamflow
and the significant decrease in specific conductance
for January, February, and March probably were
caused by an increase in the amount of stored
imported water that was released to the river,
upstream from Canon City, during low flow. The
larger flow volume increased the dilution potential
of the river during a period when base flow, which
has a larger dissolved - solids concentration and
specific conductance than the imported water,
historically represented a substantial part of the
streamflow.
Above Pueblo
The quality of water in the Arkansas River
above Pueblo (station 07099400) is important from a
drinking -water perspective because the river is the
municipal water supply for the Pueblo Board of Water
Works and for the St. Charles Mesa Water District.
The diversion point for the Pueblo water supply is
about 4 mi downstream from station 07099400
(fig. 1), and the diversion point for the St. Charles
Mesa water supply is about 8.5 mi downstream from
the station. Streamflow and specific- conductance data
were available at station 07099400 for 29 years from
1966 through 1994.
RELATIONS OF STREAMFLOW AND SPECIFIC - CONDUCTANCE TRENDS TO RESERVOIR OPERATIONS 15
IN THE ARKANSAS RIVER