Intensive Survey of the Guadalupe River Segment 1806

ABSTRACT
An intensive survey of Guadalupe River Segment 1806 was conducted
November 1-3, 1983, by the Texas Water Commission (Predecessor agency
Texas Department of Water Resources). Segment 1806 of the Guadalupe River
extends from the headwaters of Canyon Lake in Comal County to the
confluence of the North and South Forks near Hunt in Kerr County, a
distance of 168.2 km (104.5 mi). Water quality, hydraulic, and biological
data were collected at 11 mainstream stations, three tributary streams, and
the City of Kerrville wastewater treatment plant in the area upstream of SH
87 near Comfort to the upper segment boundary. Stream discharge was
relatively stable (range 1.25-1.28 m3/s) in the two reaches where
measurements were made. Stream widths were variable (9-60 m) due to
natural changes in topography and repeated mainstream impoundments located
within the segment and stream velocities were moderate (0.078-0.12 m/s).
Dissolved oxygen levels remained above the 5 mg/L stream criterion
throughout the diurnal period at all mainstream stations. Levels of
nitrogenous and carbonaceous oxygen demanding substances were low
throughout the study area. Orthophosphorus and nitrate nitrogen levels were
low enough to suggest that either would be limiting to aquatic plant growths
in different areas of the stream. Chlorophyll a levels were less than 2 yg/L
at most stations reflecting the low primary productivity of the stream.
Chloride, sulfate, total dissolved solids, water temperature, pH and fecal
coliform levels generally conformed to segment criteria. Benthic
macroinvertebrate community structure reflected clean water and stable
environmental conditions throughout the study reach. Highest levels of
oxygen demanding substances, nutrients, chlorophyll a, chloride, sulfate, and
total dissolved solids were observed at the upstream station on Third Creek,
the tributary stream which receives periodic discharges from the City of
Kerrville wastewater treatment plant.
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