Environmental Engineering Reference
In-Depth Information
limited instances, the municipality has engaged in the expensive practice
of purchasing structures that are threatened by erosion and fl oodwaters,
allowing urban waterways more room to meander within their channel. 20
These activities are the urban equivalent to conservation land purchases
and easements in the rural Hill Country, pulling the urban fabric away
from the unpredictable fl ows of nature. But in most cases, the municipality
is stuck with a network that has evolved over the past century, with the
built environment and nature entwined in confi gurations that tend to resist
the large-scale changes required to improve water quality. 21
Building a Municipal Stormwater Program
Despite the challenges of providing fl ood and erosion control in a fl ashy
hydrologic region, the municipality has developed an internationally rec-
ognized approach to protecting and enhancing urban water quality. One
of the most renowned activities is the longstanding monitoring of wa-
ter quality conditions for watersheds throughout the city. 22 The earliest
monitoring data in Austin was collected in the late nineteenth century,
but the current program was initiated in the mid-1970s when the munici-
pal government collaborated with the U.S. Geological Survey to monitor
stormwater fl ows in eight large, mixed-use watersheds. 23 These monitor-
ing activities preceded federal permitting requirements for stormwater
management and were already well-established when Austin joined the
federally funded National Urban Runoff Program in 1981 (as described
in chapter 1). 24 A local geologist notes, “Austin already had ten years of
data before this study came about, the city was way ahead of the curve.
They had automated samplers on many urban creeks in the 1970s, which
was unprecedented at the time.” 25
Although monitoring does nothing to alleviate the tensions between
the built environment and water fl ows, it recognizes the value in tracking
how environmental conditions change over time. In addition to monitoring
activities, the municipality is well known for its early efforts to evaluate
and require end-of-pipe BMPs for urban runoff from new developments.
Austin established a national reputation in the early 1980s when it insti-
tuted water quality regulations that required high levels of treatment at-
tainable only with sand fi lters (sometimes referred to as “Austin” fi lters).
The regulations were performance-based and required specifi c pollutant
removal levels. Sand fi lters were specifi ed as the most cost-effective way
to meet these requirements and eventually became the de facto standard
for new development. The advantage of sand fi lters is that they provide a
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