Stormwater & Urban Runoff
What is stormwater?
Stormwater runoff is generated when precipitation from rain and
snowmelt events flows over land or impervious surfaces and does
not percolate into the ground. As that runoff flows over land or hard
surfaces (paved streets, parking lots, and building rooftops), it
accumulates debris, chemicals, sediment or other pollutants that
could adversely affect water quality if the runoff is discharged
untreated (into rivers, streams and oceans).
In urban areas, this runoff makes its way through the municipal
storm drain systems creating a "toxic soup" and can eventually,
depending upon the city and its stormwater management
practices, drain into the ocean. The largest source of stormwater
pollution is the general public and the most common pollutants in
urban areas can be things such as fast-food wrappers, cigarette,
styrofoam, fertilizer, motor oil, sewage overflow and animal waste.
Stormwater runoff is generated when precipitation from rain and
snowmelt events flows over land or impervious surfaces and does
not percolate into the ground. As that runoff flows over land or hard
surfaces (paved streets, parking lots, and building rooftops), it
accumulates debris, chemicals, sediment or other pollutants that
could adversely affect water quality if the runoff is discharged
untreated (into rivers, streams and oceans).
In urban areas, this runoff makes its way through the municipal
storm drain systems creating a "toxic soup" and can eventually,
depending upon the city and its stormwater management
practices, drain into the ocean. The largest source of stormwater
pollution is the general public and the most common pollutants in
urban areas can be things such as fast-food wrappers, cigarette,
styrofoam, fertilizer, motor oil, sewage overflow and animal waste.
What are the affects of stormwater pollution?
Many urban areas in California do have storm drains that will
directly flow to local water bodies. Even those storm drains that
connect to a wastewater treatment plant (San Francisco, for
example) need to be kept contaminant-free because those
wastewater treatment facilities were not designed to treat toxic
pollutants. In some cities that carry both waste and storm water in
the same pipe to treatment facilities, too much rain can flood the
system.
Pollutants that go down street storm drains can have many
negative impacts on our local waters:
Many urban areas in California do have storm drains that will
directly flow to local water bodies. Even those storm drains that
connect to a wastewater treatment plant (San Francisco, for
example) need to be kept contaminant-free because those
wastewater treatment facilities were not designed to treat toxic
pollutants. In some cities that carry both waste and storm water in
the same pipe to treatment facilities, too much rain can flood the
system.
Pollutants that go down street storm drains can have many
negative impacts on our local waters:
- Poison fish and other aquatic life
- Endanger recreational uses (swimming, boating, beaches)
- Hinder the future growth of aquatic plant life
- Clogging of sewer and storm drain systems in urban areas
- Health risk to humans within range of storm drain outlets
- Cause algae blooms that remove oxygen from natural
aquatic life
What is Stormwater Management?
Managing the quantity and quality of stormwater is called
Stormwater Management. The term Best Management Practice
(BMP) refers to structural devices and procedural practices that
treat polluted stormwater. Essentially, this means that BMPs are
control measures taken to mitigate changes to both the quantity
and quality of urban runoff. Many state and local governments in
California have enacted their own stormwater management laws
and ordinances.
Managing the quantity and quality of stormwater is called
Stormwater Management. The term Best Management Practice
(BMP) refers to structural devices and procedural practices that
treat polluted stormwater. Essentially, this means that BMPs are
control measures taken to mitigate changes to both the quantity
and quality of urban runoff. Many state and local governments in
California have enacted their own stormwater management laws
and ordinances.
What can I do to prevent stormwater pollution?
- Don't put anything in the drains but rainwater.
- DO NOT LITTER!
- Pick up after your pet.
- Discard cigarette butts in the proper receptacle, not in the
street or on sidewalks. - Bag, compost or recycle grass clippings, tree limbs, leaves
and other yard waste. - Dispose of motor oil, antifreeze, paints and other household
hazardous chemicals properly. - Be smart when you apply pesticides or fertilizers, and use
mulch as a natural fertilizer or as ground cover.
How can I learn more about stormwater management?
Many local governments in California are incorporating stormwater
into their water plans. You can learn more on your water supplier's
website and inquire into your particular local ordinance.
The City of Los Angeles has created a very thorough BMP
handbook for construction. The City of San Francisco, together with
its PUC and Port, has recently passed its own water runoff
regulations and have created a stormwater BMP booklet with
graphic fact sheets to help meet guidelines they have set in the city.
Southern Sonoma County has released a homeowner's and
landowner's guide to stormwater as well.
The State of California's CalTrans department have released a
project planning guide for new construction that can serve the
overall state. Finally, the EPA has a stormwater webpage devoted to
technical and regulatory information for municipal, industrial and
construction activities.
The Wall Street Journal recently published an great informational
article discussing a national look at cities' stormwater affects and
solutions.
Many local governments in California are incorporating stormwater
into their water plans. You can learn more on your water supplier's
website and inquire into your particular local ordinance.
The City of Los Angeles has created a very thorough BMP
handbook for construction. The City of San Francisco, together with
its PUC and Port, has recently passed its own water runoff
regulations and have created a stormwater BMP booklet with
graphic fact sheets to help meet guidelines they have set in the city.
Southern Sonoma County has released a homeowner's and
landowner's guide to stormwater as well.
The State of California's CalTrans department have released a
project planning guide for new construction that can serve the
overall state. Finally, the EPA has a stormwater webpage devoted to
technical and regulatory information for municipal, industrial and
construction activities.
The Wall Street Journal recently published an great informational
article discussing a national look at cities' stormwater affects and
solutions.
Where can I see stormwater practices in action?
The City of Los Angeles, with funding from voter-approved
Proposition O, has begun building Green Street projects. The first
one built by Public Works and Bureau of Sanitation is Oros Green
Street Project. It incorporates soil filtration and vegetative retention
treatments before it flows into the adjacent LA River through the
storm drain system. The most recent green streets project built is
the Elmer Avenue Neighborhood Retrofit Project. The LA & San
Gabriel Rivers Watershed Council and its partners completed this
construction earlier in 2010 and it incorporates newer technology
and practices such as bioswales, smart-irrigation, permeable
surfaces and solar street lights.
Santa Monica's Urban Runoff Recycling Facility, otherwise known
as SMURRF, is a great example of dealing with polluted dry
weather urban runoff. Its a multi-process facility that takes
stormwater through screening, UV disinfection, microfiltration and,
in the end, the water is pumped into the distribution system for
reuse for irrigation in the local area.
San Diego is just beginning to initiate pilot projects, with the SD
StormWater Department completing work on a green street in
Memorial Park and an upcoming "green lot" planned at Kellogg
Park in La Jolla. Read more about their local work here.
The City of Los Angeles, with funding from voter-approved
Proposition O, has begun building Green Street projects. The first
one built by Public Works and Bureau of Sanitation is Oros Green
Street Project. It incorporates soil filtration and vegetative retention
treatments before it flows into the adjacent LA River through the
storm drain system. The most recent green streets project built is
the Elmer Avenue Neighborhood Retrofit Project. The LA & San
Gabriel Rivers Watershed Council and its partners completed this
construction earlier in 2010 and it incorporates newer technology
and practices such as bioswales, smart-irrigation, permeable
surfaces and solar street lights.
Santa Monica's Urban Runoff Recycling Facility, otherwise known
as SMURRF, is a great example of dealing with polluted dry
weather urban runoff. Its a multi-process facility that takes
stormwater through screening, UV disinfection, microfiltration and,
in the end, the water is pumped into the distribution system for
reuse for irrigation in the local area.
San Diego is just beginning to initiate pilot projects, with the SD
StormWater Department completing work on a green street in
Memorial Park and an upcoming "green lot" planned at Kellogg
Park in La Jolla. Read more about their local work here.
How are stormwater and urban runoff different?
Stormwater runoff is water that flows after a rainfall. Once
stormwater enters the storm sewer system of inlets, pipes or
channels, it flows downstream to the nearest creek, lake, river or
ocean. It can pick up pollutants along its way.
Urban runoff also flows to the storm sewer system. Urban runoff is
water from irrigation, overwatering, car washing and other sources
that travels into the street picking up pollutants as well.
Stormwater runoff is water that flows after a rainfall. Once
stormwater enters the storm sewer system of inlets, pipes or
channels, it flows downstream to the nearest creek, lake, river or
ocean. It can pick up pollutants along its way.
Urban runoff also flows to the storm sewer system. Urban runoff is
water from irrigation, overwatering, car washing and other sources
that travels into the street picking up pollutants as well.
How does urban runoff affect drinking water?
Because urban runoff consists of water that has drained from
non-porous surfaces in densely populated areas, any form or
amount of precipitation and irrigation can scour these surfaces and
wash away all the materials that sit on top.
This suspended sediment is the primary pollutant in urban runoff
which includes basic trash, cigarette butts, motor oil, grease,
pesticides, gasoline and toxic chemicals from automobiles, and
other daily use items. These types of materials are allowing for
increased human health risks in our surface water. When surface
waters are used as potable water supplies, they can be
compromised.
A report by NRDC on Community Responses to Runoff Pollution is
a resource for citizens concerned about the quality of their local
environment. The EPA Urban Runoff website offers fact sheets
related to nonpoint source (NPS) pollution, urban runoff.
Because urban runoff consists of water that has drained from
non-porous surfaces in densely populated areas, any form or
amount of precipitation and irrigation can scour these surfaces and
wash away all the materials that sit on top.
This suspended sediment is the primary pollutant in urban runoff
which includes basic trash, cigarette butts, motor oil, grease,
pesticides, gasoline and toxic chemicals from automobiles, and
other daily use items. These types of materials are allowing for
increased human health risks in our surface water. When surface
waters are used as potable water supplies, they can be
compromised.
A report by NRDC on Community Responses to Runoff Pollution is
a resource for citizens concerned about the quality of their local
environment. The EPA Urban Runoff website offers fact sheets
related to nonpoint source (NPS) pollution, urban runoff.
| View of SMURRF from Appian Way, south of the Santa Monica Pier. |
| Image of a rain filled bioswale in the Elmer Avenue Green Streets Project. |
| Bioswales in Downtown Los Angeles |
Articles of interest on local stormwater issues:
Keeping trash from going with the flow - LA Times
Keeping trash from going with the flow - LA Times
| Scientific American |