Fort Worth O
Midland
Waco
"Austin
Houston
San Antonio
>us Christi
McAllen
Key:
Intermittent, ephemeral, and
headwater stream miles as
percentage of total stream
miles contained in all SPAs
for a given county
0.36% - 44%
44% -56%
57% - 69%
70% - 86%
87% - 100%
No Data
Percentage of Surface Drinking Water from Intermittent,
Ephemeral, and Headwater Streams in Texas











•
cti 1
















Lubbock
o










Dallas
o





Legend: This map highlights regional
patterns of dependence on
intermittent, ephemeral, and headwater
streams for surface drinking water in
Texas. In Texas, 20,483 total miles of
streams provide water for surface water
intakes supplying public drinking water
systems; of this, 12,570 miles, or 61%,
are intermittent, ephemeral, or
headwater streams. Over 11.5 million
people in Texas receive drinking water
from public drinking water systems
that rely at least in part on intermittent,
ephemeral, or headwater streams. This
analysis compared the stream length of
intermittent, ephemeral, and headwater
streams to total stream length within all
mapped Source Protection Areas
(SPAs) for each county. A SPA is an
area upstream from a drinking water
source or intake that contributes
surface water flow to the drinking
water intake during a 24-hour period.
This is based on data that generally do
not include streams less than one mile
in length. Intermittent streams are
streams containing water for only part
of the year. Ephemeral streams flow in
response to precipitation events. First-
order streams have been used to
represent headwater streams.
Data Sources: National Hydrography
Dataset Plus at medium resolution;
Federal Safe Drinking Water
Information System 4th Quarter 2006
Data.

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