Since 2014, the San Antonio River Authority (River Authority) has provided incentives such as rebates for the creation of green infrastructure features. The River Authority has also created an interactive green infrastructure dashboard (below) that provides information about the amount of stormwater and select pollutants that the features manage.
Stormwater runoff is the greatest threat to river health in the San Antonio River watershed with many other US communities reporting the same problem. Unlike pollution from an industrial pipe, which can be traced to its source, stormwater runoff can originate from anywhere within our watershed such as parking lots, rooftops, unsecured construction sites, roadways, and even our own yards. In urban areas, runoff is designed to be carried from these surfaces to the storm drain system and then directly to a nearby river, creek, or stream.
In our watershed, stormwater runoff is not cleaned at a treatment plant before being discharged into the environment. Pollutants like oil, grease, metals, bacteria, sediment, fertilizers, pesticides, pet waste, and thermal pollution accumulate on the surfaces. During rains, runoff carries the pollutants to our creeks and rivers and during hard downpours, runoff can contribute to street and neighborhood flooding. Stormwater runoff prevents creeks and rivers from primary and secondary contact recreation during and for approximately 72 hours after rain events. Over time, surges of runoff from urbanized areas erode creek banks and can negatively affect bridge and other community infrastructure.
Green infrastructure is a design and land development approach that alleviates these negative runoff impacts. Bioretention systems, stormwater cisterns, permeable pavement, buffers, retention of native infiltrative soils, green space preservation, natural channel (river) design, and several other sustainable development approaches perform natural or nature-mimicking functions that slow, capture, and/or clean stormwater runoff—like nature intended. The design and installation of green infrastructure meets our goals of reducing local flooding and improving water quality by mimicking natural areas to slow, detain, and filter stormwater.
Unlike a storm drain and concrete-lined river segment, which are designed for the singular purpose of water passage, green infrastructure provides multiple benefits.
Along with reducing neighborhood flooding and pollution in our creeks and rivers, green infrastructure benefits include:
- reducing the heat island effect
- improving human health
- creating or preserving valuable wildlife habitat, including for monarchs, bees, and other pollinators essential to our human food supply
Learn more in this module about the benefits of green infrastructure and what you can do to help protect our creeks and rivers.
Treated Stormwater Volume is the volume of stormwater treated by Green Infrastructure methods to improve water quality, using one or more processes: infiltration, filtration, pollutant settling, or bioremediation. Treated Stormwater Volume is measured in cubic feet (1cubic foot = 7.5 gallons).
Bioretention, called rain gardens, are shallow landscaped areas designed to slow and clean stormwater runoff, reduce local flooding, and protect stream health.
|Bioswales are shallow vegetated drainage paths that soak up and filter stormwater runoff from roofs or pavement. Bioswales are constructed with quick-draining soil and drainage layers to filter stormwater and provide water for plants.|
|Cisterns are containers that store primarily roof runoff, keeping stormwater on-site during storms to mitigate flooding and often used later for supplementary watering.|
|Permeable Pavement is a load-bearing paving method that allows for infiltration, on-site storage, and settling of stormwater pollutants to clean and reduce runoff during a storm.|
Sediment are fine particles suspended in stormwater. Sediment from stormwater makes streams and rivers appear cloudy which affects the health of all river plants and animals. Other pollutants such as nutrients, metals and bacteria attach to sediment and are deposited at the stream bottom where they can harm plants and animals.
|Bacteria measures fecal coliform bacteria which is measured in number of colonies. Fecal coliform is used as an indicator of contamination with other pathogens which cause disease in humans. When bacterial levels are high, human contact can result in sickness. Reducing bacteria makes the river safe for contact activities.|
|Green Roof are rooftop planted areas that reduce or eliminate runoff leaving the roof through stormwater capture, plant uptake, and evapotranspiration.|