STORM WATER MANAGEMENT AND ITS ENVIRONMENTAL IMPACT QUESTIONS WELL ANSWERED
LATEST UPDATE 2026
Surface Runoff - Answers Water flowing by gravity into streams,
rivers, ponds, lakes, and oceans.
-Occurs quickly on impervious surfaces (e.g., roads, roofs)
Subsurface Runoff - Answers Slow water movement (horizontal & vertical) through soil, influenced by
permeability.
-Usually occurs slower than surface runoff
Impervious Surfaces - Answers Surfaces that prevent water infiltration, like roads and pavement.
Hydrologic Cycle Disruption - Answers Alteration of natural water movement due to development.
Hydrologic Cycle Disruption: Development Effects - Answers Reduces infiltration and vegetation
uptake
Accelerates runoff and reduces natural hydrologic functions
Alters stream flow, volume, velocity, and raises flood risks
Hydrologic Cycle Disruption: Stream Impacts - Answers Peak discharges can increase 2-5x, causing
flooding
Reduced infiltration lowers groundwater recharge
Stream banks erode; sediment fills channels, reducing capacity
Runoff contains pollutants from cars, construction, fertilizers, etc.
Management Philosophy: Traditional Approach - Answers Traditional: Move water off-site quickly
using sewers/channels
Management Philosophy: Contemporary Approach - Answers Contemporary: Manage on-site
through detention, infiltration, and treatment
Management Philosophy: New Goal - Answers Maintain natural drainage patterns and reduce runoff
at the source
Infiltration - Answers Allows water to soak into soil to recharge groundwater
Dependent on water table depth and soil type
Infiltration Systems - Answers reduce surface runoff by filtering it through the soil layer, but should
not be used to remove sediment as they can clog the system.
ie. surface trench, porous pavement
Peak Discharge - Answers Maximum flow rate in a stream during flooding.
Detention - Answers Temporary water storage, released at controlled rates.
Evapotranspiration - Answers Water release from plants, combining evaporation and transpiration.
Bioretainment - Answers Using plants to retain and treat stormwater.
Water Quality Treatment - Answers Processes to improve stormwater quality before discharge.
Sedimentation - Answers Slowing water to allow solids to settle out.
Filtration - Answers Water passing through vegetation and soil for purification.
Plant Resistance - Answers Plants slowing flow and enhancing pollutant uptake.
Thermal Attenuation - Answers Cooling heated runoff through infiltration.
Adsorption - Answers Soil binding and removing soluble pollutants from water.
Phytoremediation - Answers Plants absorbing and storing toxins and nutrients.
Volatilization - Answers Conversion of pollutants to gas phase, like CO₂.
Storm Water Management Strategies: Watershed-Based Management - Answers More effective than
site-by-site approaches
Emphasizes land planning, public education, and regional detention solutions
Watershed zoning can limit impervious cover based on stream protection goals
Storm Water Management Strategies: Site Planning Techniques - Answers Reduce impervious cover
to protect water quality
Degradation begins when imperviousness >20% of drainage area
Strategies to Reduce Impervious Surfaces - Answers Parking lots
Street width
Cluster development
Strategies to Reduce Impervious Surfaces: Street Width - Answers Reduce from standard widths to
cut paved area
Enables tree planting and bioretention in right-of-way
Strategies to Reduce Impervious Surfaces: Parking Lots - Answers Use realistic demand estimates
LATEST UPDATE 2026
Surface Runoff - Answers Water flowing by gravity into streams,
rivers, ponds, lakes, and oceans.
-Occurs quickly on impervious surfaces (e.g., roads, roofs)
Subsurface Runoff - Answers Slow water movement (horizontal & vertical) through soil, influenced by
permeability.
-Usually occurs slower than surface runoff
Impervious Surfaces - Answers Surfaces that prevent water infiltration, like roads and pavement.
Hydrologic Cycle Disruption - Answers Alteration of natural water movement due to development.
Hydrologic Cycle Disruption: Development Effects - Answers Reduces infiltration and vegetation
uptake
Accelerates runoff and reduces natural hydrologic functions
Alters stream flow, volume, velocity, and raises flood risks
Hydrologic Cycle Disruption: Stream Impacts - Answers Peak discharges can increase 2-5x, causing
flooding
Reduced infiltration lowers groundwater recharge
Stream banks erode; sediment fills channels, reducing capacity
Runoff contains pollutants from cars, construction, fertilizers, etc.
Management Philosophy: Traditional Approach - Answers Traditional: Move water off-site quickly
using sewers/channels
Management Philosophy: Contemporary Approach - Answers Contemporary: Manage on-site
through detention, infiltration, and treatment
Management Philosophy: New Goal - Answers Maintain natural drainage patterns and reduce runoff
at the source
Infiltration - Answers Allows water to soak into soil to recharge groundwater
Dependent on water table depth and soil type
Infiltration Systems - Answers reduce surface runoff by filtering it through the soil layer, but should
not be used to remove sediment as they can clog the system.
ie. surface trench, porous pavement
Peak Discharge - Answers Maximum flow rate in a stream during flooding.
Detention - Answers Temporary water storage, released at controlled rates.
Evapotranspiration - Answers Water release from plants, combining evaporation and transpiration.
Bioretainment - Answers Using plants to retain and treat stormwater.
Water Quality Treatment - Answers Processes to improve stormwater quality before discharge.
Sedimentation - Answers Slowing water to allow solids to settle out.
Filtration - Answers Water passing through vegetation and soil for purification.
Plant Resistance - Answers Plants slowing flow and enhancing pollutant uptake.
Thermal Attenuation - Answers Cooling heated runoff through infiltration.
Adsorption - Answers Soil binding and removing soluble pollutants from water.
Phytoremediation - Answers Plants absorbing and storing toxins and nutrients.
Volatilization - Answers Conversion of pollutants to gas phase, like CO₂.
Storm Water Management Strategies: Watershed-Based Management - Answers More effective than
site-by-site approaches
Emphasizes land planning, public education, and regional detention solutions
Watershed zoning can limit impervious cover based on stream protection goals
Storm Water Management Strategies: Site Planning Techniques - Answers Reduce impervious cover
to protect water quality
Degradation begins when imperviousness >20% of drainage area
Strategies to Reduce Impervious Surfaces - Answers Parking lots
Street width
Cluster development
Strategies to Reduce Impervious Surfaces: Street Width - Answers Reduce from standard widths to
cut paved area
Enables tree planting and bioretention in right-of-way
Strategies to Reduce Impervious Surfaces: Parking Lots - Answers Use realistic demand estimates
