Low Impact Development & Nonpoint Source Pollution
Transcript
Slide 1
Low Impact Development & Nonpoint Source Pollution
Slide 2
Define Low Impact Development LID is an approach to land
development (or re-development) that works with nature to manage
storm water as close to its source as possible. LID employs
principles such as preserving and recreating natural landscape
features, minimizing effective imperviousness to create functional
and appealing site drainage that treat storm water as a resource
rather than a waste product. There are many practices that have
been used to adhere to these principles such as bioretention
facilities, rain gardens, vegetated rooftops, rain barrels, and
permeable pavements. By implementing LID principles and practices,
water can be managed in a way that reduces the impact of built
areas and promotes the natural movement of water within an
ecosystem or watershed. Applied on a broad scale, LID can maintain
or restore a watershed's hydrologic and ecological functions.
Slide 3
Nonpoint Source Pollution Excess fertilizers, herbicides, and
insecticides from agricultural lands and residential areas Oil,
grease, and toxic chemicals from urban runoff and energy production
Sediment from improperly managed construction sites, crop and
forest lands, and eroding stream banks Salt from irrigation
practices and acid drainage from abandoned mines Bacteria and
nutrients from livestock, pet waste, and faulty septic systems
Atmospheric deposition and hydromodification
Slide 4
Nonpoint Source Pollution cont. Comes from many diffuse sources
such as rainfall or snowmelt moving over and through the ground
Results from land runoff, precipitation, atmospheric deposition,
drainage, seepage, or hydrologic modification
Slide 5
Impacts of land use on watersheds Land uses from any part of
the watershed -- such as polluted runoff from farms, forests and
homes -- eventually affect the health of the whole watershed. Land
use practices such as clearing land for timber or agriculture,
developing and maintaining roads, housing developments, and water
diversions may have environmental consequences that greatly affect
stream conditions even when the activity is not directly associated
with or near a stream. Proper planning and adequate care in
implementing projects can help ensure that one activity within a
watershed does not detrimentally impact the downstream
environment.
Slide 6
In a healthy watershed, after a rain event, vegetation and
wetlands intercept and slow the flow of water as it travels through
the watershed, removing sediment and allowing large quantities of
water to enter the soil and percolate into the groundwater. This
groundwater is then available to contribute to late season stream
flow, to the benefit of fisheries and water quality. In comparison,
a watershed with more impervious surfaces and the loss of
vegetation and wetlands, responds differently after a rain event.
More water runs over the land instead of replenishing groundwater.
This larger volume of water quickly reaches water bodies reducing
the time available for the water to be cleansed and filtered and
also causing erosion of stream banks.
Slide 7
Most human activities and development have the potential to
adversely affect the overall health and quality of a watershed.
Timber harvest on unstable slopes can cause erosion. Agricultural
activities can increase levels of harmful bacteria and overload
runoff with nutrients. Also, poorly planned urban and industrial
growth can cause many of the same problems as farming and timber
harvest in addition to contamination from toxic chemicals. Even
seemingly harmless activities such as rural development and
recreational activities along rivers and creeks can be harmful,
impacting the watershed's sensitive riparian vegetation which is
important for water quality protection and wildlife habitat.
Slide 8
When viewed individually, most human activities have little
effect on the general health of the watershed. However, the effects
of numerous activities within a watershed are cumulative and when
combined can greatly diminish the watershed's overall health. Every
activity has the potential to impact the area of the watershed
downstream. As people place more demands on a watershed, greater
efforts must be made to reduce these cumulative effects. Having
clean water will require communities to work together to ensure
that activities do not negatively impact those downstream.
Slide 9
In the 2000 National Water Quality Inventory, states reported
that agricultural nonpoint source (NPS) pollution is the leading
source of water quality impacts on surveyed rivers and lakes, the
second largest source of impairments to wetlands, and a major
contributor to contamination of surveyed estuaries and ground
water. Agricultural activities that cause NPS pollution include
poorly located or managed animal feeding operations; overgrazing;
plowing too often or at the wrong time; and improper, excessive, or
poorly timed application of pesticides, irrigation water, and
fertilizer. Pollutants that result from farming and ranching
include sediment, nutrients, pathogens, pesticides, metals, and
salts. Impacts from agricultural activities on surface water and
ground water can be minimized by using management practices that
are adapted to local conditions. Many practices designed to reduce
pollution also increase productivity and save farmers and ranchers
money in the long run.
Slide 10
Did you know that runoff from farms is the leading source of
impairments to surveyed rivers and lakes? There are many government
programs available to help farmers and ranchers design and pay for
management approaches to prevent and control NPS pollution. For
example, over 40 percent of section 319 Clean Water Act grants have
been used to control NPS pollution from working farms and ranches.
Also, many programs funded by the U.S. Department of Agriculture
and by states provide cost-share, technical assistance, and
economic incentives to implement NPS pollution management
practices. Many local organizations and individuals have come
together to help create regional support networks to adopt
technologies and practices to eliminate or reduce water quality
impacts caused by agricultural activities.
Slide 11
Conventional Development vs. LID: Conventional development
techniques often clear all trees and valuable topsoil from a site
and re-grade it so that all water ends up in one large detention
basin. Resulting problems include loss of recharge, increased water
temperature, decreased water quality and higher runoff volumes. The
LID approach protects the natural ability of the site to capture
precipitation, keep it clean and allow it to recharge the local
water table.
Slide 12
Slide 13
LID Best Management Practices and selection criteria The use of
best management practices to reduce the amount of impervious
surfaces, disconnect flow paths (i.e., downspouts connected to
storm sewers), and treat storm water at its source all help
minimize the impacts to water quality and local hydrology.
Slide 14
Pros of applying LID Provides energy at an affordable cost
Minimizes land clearing and grading costs Reduces infrastructure
costs (streets, curbs, gutters, sidewalk) Reduces storm water
management costs (reduces or eliminates storm sewers and ponds)
Increases lot and community marketability Increases lot sale yields
and reduces permit fees
Slide 15
Pros cont. Protects site and regional water quality by reducing
sediment, nutrient, and toxic loads to water bodies Balances growth
needs with natural resource protection Reduces municipal
infrastructure and utility maintenance costs (streets, curbs,
gutters, sidewalks, storm sewers and ponds) Fosters public/private
partnerships Provides local accessibility to open spaces,
recreation and wildlife areas Preserves and protects amenities that
can translate into more saleable homes and communities Provides
shading for homes and properly orients homes to help decrease
monthly utility bills
Slide 16
Pros cont. Preserves integrity of ecological and biological
systems Protects site and regional water quality by reducing
sediment, nutrient, and toxic loads to water bodies Reduces impacts
to local terrestrial and aquatic plants and animals Preserves trees
and natural vegetation Creates connected corridors of wildlife
habitat
Slide 17
Cons Supplies have to be specially ordered Not significantly
different compared to what we already have Not well known People
refuse to use it.
Slide 18
Hydrologic Controls Clustering buildings Building set backs
Naturally vegetated buffers Natural vegetation should be preserved
Steep slopes should not be disturbed Rain gardens Bio retention
areas Grassed swales Native plant landscaping
Slide 19
Hydrologic Controls Permeable or porous pavement Reduced in
impervious surfaces Disconnected down spouts (Rain barrels) Green
roofs
Slide 20
Rain Garden Green roof system
Slide 21
What can communities do? Start using LID for community
building/municipal center Make laws to enforce LID Promote LID
Encourage others to use LID Reach out to developers Get projects on
the ground Make sure ordinances are LID friendly Use less
pavement
Slide 22
Soils, wildlife, forestry, and aquatics affect and are affected
by nonpoint source pollution and its reduction and LID Polluted
storm water runoff can have many adverse effects on plants, fish,
animals, and people. Sediment can cloud the water and make it
difficult or impossible for aquatic plants to grow. Sediment also
can destroy aquatic habitats Excess nutrients can cause algae
blooms. When algae die, they sink to the bottom and decompose in a
process that removes oxygen from the water. Fish and other aquatic
organisms cant exist in water with low dissolved oxygen levels.
Bacteria and other pathogens can wash into swimming areas and
create health hazards, often making beach closures necessary.
Slide 23
Slide 24
Debrisplastic bags, six-pack rings, bottles, and cigarette
buttswashed into water bodies can choke, suffocate, or disable
aquatic life like ducks, fish, turtles, and birds. Household
hazardous wastes like insecticides, pesticides, paint, solvents,
used motor oil, and other auto fluids can poison aquatic life. Land
animals and people can become sick or die from eating diseased fish
and shellfish or ingesting polluted water. Polluted storm water
often affects drinking water sources. This, in turn, can affect
human health and increase drinking water treatment costs.
Slide 25
Auto care Washing your car and degreasing auto parts at home
can send detergents and other contaminants through the storm sewer
system. Dumping automotive fluids into storm drains has the same
result as dumping the materials directly into a water body.
Slide 26
Lawn care Excess fertilizers and pesticides applied to lawns
and gardens wash off and pollute streams. In addition, yard
clippings and leaves can wash into storm drains and contribute
nutrients and organic matter to streams.
Slide 27
Septic Systems Leaking and poorly maintained septic systems
release nutrients and pathogens (bacteria and viruses) that can be
picked up by storm water and discharged into nearby water bodies.
Pathogens can cause public health problems and environmental
concerns.
Slide 28
Pet waste Pet waste can be a major source of bacteria and
excess nutrients in local waters.
Slide 29
Dirt, oil, and debris that collect in parking lots and paved
areas can be washed into the storm sewer system and eventually
enter local water bodies. Erosion controls that arent maintained
can cause excessive amounts of sediment and debris to be carried
into the storm water system. Construction vehicles can leak fuel,
oil, and other harmful fluids that can be picked up by storm water
and deposited into local water bodies.
Slide 30
Improperly managed logging operations can result in erosion and
sedimentation. Uncovered fueling stations allow spills to be washed
into storm drains. Cars waiting to be repaired can leak fuel, oil,
and other harmful fluids that can be picked up by storm water.