The City's sole source of drinking water is pumped from the Edwards Aquifer.
Water is secured from four operational wells. One of two inoperable wells
is being utilized by the EAA for water quality monitoring. In addition, the
City is drilling a water well into the Trinity Aquifer in order to diversify the
City's water resources. The Trinity aquifer lies below the Edwards Aquifer
along the northern part of our City. All Trinity aquifer regulatory authorities'
boundaries end at Loop 1604, thus allowing the City to develop it's own conservation
program and rules.
706 water customers receive water service either from Shavano Park or the San Antonio
Water System (SAWS). Residents of Shavano Creek and Bentley Manor including
the commercial areas on Loop 1604 and Lockhill Selma receive water and sewer services
from SAWS.
What is “Stormwater”?
Stormwater is any water that results from a storm - typically a rainfall event.
Three things can happen to that rainwater. It can enter the ground and recharge
aquifers and help feed a nearby stream's base flow (a critical role in those dry
summer months). It can evaporate into the atmosphere or be used by plants in their
life cycle, or it can flow over land to streams, wetlands, ponds, etc. All three
avenues are part of the natural hydrologic system.
Over time, stormwater runoff has had a major influence on the characteristics of
our waterways, helping to shape their floodplains. Bank widths, stream slope, channel
shape, and sinuosity (its curves and bends). These characteristics began to change
as land that was historically covered in mature forests was cleared for logging
and agriculture.
Over the last one hundred years, we have again changed the land and its associated
runoff characteristics through increased suburban and urban development. That
has meant more roads, parking lots, and buildings that are impervious to rain water
infiltrating the ground. The result is greater volumes of runoff hitting our streams
with greater frequency and more ferocity.
Stream characteristics that evolved under forest conditions cannot handle this added
power and volume as the rain waters move through the watershed. The erosive force
of water gouges stream banks, smothers aquatic organisms, and changes the shape
of stream channels. Flooding becomes more frequent and high waters increase bridge
scour by undercutting bridge piers and supports, downstream, increased loads of
sediment and pollution are delivered to bays and reservoirs, adding costs to water
suppliers that use stream intakes and disrupting the delicate balance of estuarine
ecosystems, such as the Chesapeake Bay. Meanwhile, upstream groundwater reserves
dwindle as more stormwater is literally exported to the mouth of the watershed.
Why is this important to you and what can you do about it? After all, stormwater
management is the domain of engineers, you say.
Not exactly. While stormwater management practices are designed by engineers, a
basic understanding of the latest management approaches and techniques will empower
you to provide educated input into the making of local ordinances that are the backbone
of stormwater management programs. In fact, much of the new thinking behind stormwater
controls is easier to understand because it encourages the use of the landscape's
natural features to reduce flooding and pollution. Simple, effective, and economic
are words commonly used to describe the latest promotions in stormwater management.
Consider also the costs associated with not managing stormwater effectively -- the
expense of flood control projects, flood repair, drinking water purification, dredging
of shipping channels clogged with sediment, maintenance of stormwater infrastructure,
and habitat restoration. There's the aesthetic and ecological value that stormwater
management devices can have in your community as well. Did you know that there are
alternatives to the detention basins that are fixtures in today's suburban developments?
Many of these alternatives are better looking, provide better habitat for wildlife,
and are a better buy for reducing runoff and pollution to our streams. In short,
they promise good-looking, multi-functional landscapes.
Historically, there have been major shifts in how stormwater runoff has been managed
by society. More than a hundred years ago, open ditches in towns and cities carried
away stormwater, human wastewater, and debris creating nothing more than urban cesspools.
Fifty years ago, storm runoff and wastewater were put into pipes, all of which was
discharged directly into streams and rivers with no treatment systems. (Today, these
combined stormwater and sanitary sewers are still found in many older cities and
there remains the problem of "combined sewer overflows," or CSO's, which allow untreated
sewage to be discharged to streams during storm events.)
By the 1940's, health problems led to the separation of stormwater and waste water
pipes, and the modern urban drainage infrastructure was born, consisting of an efficient
drainage system with catch basins and pipes leading to the nearest stream. By the
1970's, however, the unforeseen fruit of such a system was downstream flooding and
channel erosion. Back to the drawing board.
The paradigm of the 70's was to keep post-development stream flow at pre-development
flow levels. The answer seemed to be large stormwater detention basins, which were
designed to detain runoff from diffuse areas for a period of time, slowing and releasing
it to a receiving stream. The goal was to get stormwater off site as fast as possible.
Roof runoff was channeled through gutters, down driveways, into the street and through
storm sewers to the nearest detention pond. Quick conveyance was the thinking of
the day.
The biggest problem with detention basins is that they only control flood peaks,
not the total volume of water released to a stream. A good analogy is a city traffic
jam in which three major events all end within a half-hour of each other. Each parking
lot releases only so many cars at once, much like a detention pond. But dozens of
lots are all letting out cars at a controlled rate to the same main artery. The
problem is a car volume problem, not a peak-flow problem. With stormwater, the peak
of runoff may be controlled directly below a detention pond, but, downstream, where
the total drainage area may be ten times the area detained by one basin upstream,
the stream cannot handle the cumulative volume of the water being released simultaneously.
The result is more flooding, combined sewer overflows, and stream habitat degradation
and thermal pollution.
The other problem with large detention basins is that they do little to improve
water quality, which became the 1980's challenge in stormwater management as a result
of the movement to reduce "nonpoint source pollution," or pollutants that run off
the land from diffuse points. Efforts to control stormwater quantity and stormwater
quality became increasingly intertwined, and detention basins generally fell short
of meeting both goals. (Some contaminants that attach to sediment may be broken
down by microorganisms in detention basins, but to a limited degree.) New ap-proaches
were being tested in stormwater management to positively impact the biological health
of a stream. No longer could engineers work alone in designing stormwater systems
they needed the expertise of ecologists and biologists to address the whole picture.
Current thinking revolves around looking holistically at the local watershed, since
everything that happens in a watershed affects its stream corridors. Development
standards, gardening, changing the oil in your car, floodplain uses, road maintenance,
local ordinances, etc. can all be done differently to protect our streams. Stormwater
management is but one component of watershed protection that is undergoing a revolution
of sorts to create functional, environmentally-friendly, sustainable, and beautiful
living environments.
Managing stormwater is now part of the paradigm that promotes small-scale, distributed
controls that reduce the impacts of development. As with past paradigms, some innovations
will work while others will fail. Regardless, this approach demands that local governments
understand the rapid departure from conventional thinking gathering and storing
runoff from a large area and getting rid of it as quickly as possible - to today's
thinking that promotes dispersed, on-site practices that slow down and cleanse runoff
as it flows to underlying groundwater or a receiving stream.
Stormwater management is no longer the sole province of engineers. Ecologists, biologists,
planners, and economists should all have input into the direction and implementation
of stormwater management programs. Citizens, whether motivated by the financial,
environmental, or recreational aspects of the big picture, can play an important
role in how the latest stormwater management paradigm plays out.