| Strategy Class | Implementation Strategy | Applications | Benefits | Cost | Barriers to Implementation |
| Green | Bioretention planter | Local, small scale, easily implemented in developed areas | Protects property, treats runoff | $2500 ea | Limited volume disposed of, so many are needed, maintenance |
| Green | Tree box filter | Local, small scale, easily implemented in developed areas | Protects property, treats runoff | $2500 ea | Limited volume disposed of, so many are needed, maintenance |
| Green | Rainwater harvesting | Local, small scale, easily implemented in developed areas | Protects property, treats runoff | Under $5000 | Limited volume disposed of, so many are needed, maintenance |
| Green | Vegetated roof | Specific to a building, absorbs water, reduces runoff | Protects property, treats runoff | $100/sf | Requires irrigation if insufficient rainfall occurs Requires runoff control if too much rainfall occurs |
| Green | Bioswale | Parking lots, runoff from development—primarily treatment for discharge to another system | Protects property, treats runoff | $20 K/ac | Maintenance, limited volume disposed of, used mostly for treatment |
| Gray | Pervious paving | Parking lots, patios, driveways, anything except paved roads due to traffic loading | Reduces roadway and parking lot flooding | $10 - 20/sf, requires bumpers and sub-base to maintain paver integrity | Must be maintained via vacuuming or the perviousness fades after 2 - 3 years |
| Green | Detention | Common for new development, but difficult to retrofit; limited to open areas | Removes water from streets, reduces flooding | $200 K/ac | Land availability, maintenance of pond, discharge location Uses up land that could otherwise be developed |
| Green | Vegetated wall | Used on walls of buildings and retaining walls | Protects property, treats runoff | $30/sf | Requires irrigation if insufficient rainfall occurs Requires runoff control if too much rainfall occurs |
| Gray | Exfiltration Trench | Any low-lying area where stormwater collects and the water table is more than 3 ft below the surface; densely developed areas where retention is not available, roadways | Excess water drains to aquifer, some treatment provided | $250/ft | Significant damage to roadways for installation, maintenance needed, clogging issues reduce benefits |
| Green | Dry Swale | Parking lots, runoff from development—primarily treatment for discharge to another system | Protects Property, treats runoff | $200 K/mi | Maintenance, limited volume disposed of, mostly for treatment |
| Green | Retention Ponds | Common for new development, but difficult to retrofit; limited to open areas | Removes water from streets, reduces flooding | $200 K/ac | Land availability, maintenance of pond, discharge location Uses up land that could otherwise be developed |
| Green | Rain Gardens | Local, small scale, easily implemented in developed areas | Protects property, treats runoff | $20 K/ac | Limited volume disposed of, so many are needed, maintenance |
| Gray | Infiltration Trench | Low lying areas that collect stormwater, but the water table is just below the surface meaning that retention and exfiltration trenches will not work properly | Excess water is drained to pump stations, creating soil storage capacity to store runoff, soil treatment | $250/ft plus pump station | Significant damage to roadways for installation, maintenance needed, clogging issues—must discharge somewhere (pump station, detention pond) |
| Green | Oversized pipes | Local solution—not watershed level, holds water to reduce flooding | Protects property and roadways | $350/ft of more | Sediments, maintenance needs, lack of means to flush, cost |
| Gray | Central sewer installation | All areas where there are septic tanks. Mostly a water quality issue | Public health benefit of reducing discharges to lawns, canals and groundwater from septic tanks | $15,000 per household | Cost, assessments against property owners, property rights issues |
| Green | Filter strips | Localized | Protects property, treats runoff | $50 K/mi | Does not address flooding, treatment/water quality measure |
| Green | Flood prone property acquisition | Regional agency—could be any low-lying areas | Removes flood prone areas from risk | $2 K - $100 K/ac depending on whether it is already developed | Difficult to implement if occupied, issues with willing sellers, cost, lack of funds for acquisition |
| Gray | Class I injection wells | Any low-lying area where stormwater collects, and there is sufficient land to permit, install and operate a Class I well-limited | Means to drain neighborhoods— potentially arge volumes | $3-6 million depending on size/depth | Needs baffle box, injection zone may not be available, requires a permit, may compete with water users |
| Green | Underground storage | Common for new developments, but difficult to retrofit | Storage of excess runoff from rainfall, can be used for irrigation, can sit under parking lots, unobtrusive | $2/gal | If the tank is full, there is no storage |
| Green | Constructed wetlands | Where there is low lying flood prone land that can be converted into wetlands | Reduces flooding by providing a low-lying area for water to go | $200 - $1 M/ac | Water quality, permitting, monitoring costs, maintenance |
| Gray | Pump stations | Any low-lying area where stormwater collects, and there is a place to pump the excess stormwater to such as a canal; common for developed areas | Removes water from streets, reduces flooding | Start at $1.5 to 5 million each, number unclear without more study | NPDES permits, maintenance cost, land acquisition, discharge quality |
| Gray | Armored sewer systems | Any area where gravity sanitary sewers are installed | Keeps stormwater out of sanitary sewer system and reduces potential for disease spread from sewage overflows | $500/manhole | Limited expense beyond capital cost |
| Gray | Raised roadways | Limited to areas where redevelopment is occurring areawide due to ancillary impacts on adjacent properties | Keeps traffic above floodwaters, access for emergency vehicles, commerce | $2 - 4 million/lane mile | Runoff, cost, utility relocation |
| Gray | Class V gravity wells | Any low-lying areas where stormwater collects and is located where saltwater has intruded the surficial aquifer beneath the site | Means to drain neighborhoods, limited volume | $250 K each | Needs baffle box, limited flow volume (1 MGD), zone for discharge may not be available, permits, water supply wells |
| Gray | Canals | Limited | Means to drain neighborhoods, provides treatment of water | $2 million/mile | Land area, flow volume, maintenance, ownership, capacity issues due to sea level rise pressure |
| Green | Aquatic zones | Any low-lying or flood-prone area that is undeveloped and can store large volumes of water | Place to store large volumes of water | $200 K/ac | Must be maintained, cost, impact on property owners |
| Gray | Levees | Regional issue—along rivers, lakes, impoundments | Protects widescale property | $ millions | Must be maintained, must be continuous, must be planned for extreme events (i.e. Hurricane Katrina showed that New Orleans planning horizon was not sufficient) |
| Gray | Lock structures | Regional (WMD) responsibility | Keeps seawater out, reduces saltwater intrusion | Up to $10 million, may require ancillary stormwater pumping stations at $2 - 5 million each | Permitting, private property rights arguments |
| Gray | Sea walls | Barrier islands and downtown coastal areas | Protects property | $1200/ft | Private property rights, neighbors |
| Green | Polders | Barrier islands and downtown coastal areas | Provides storage for coastal waters | $200 K/ac | Permitting, land acquisition |
| Gray | Surge barriers | Coastal communities—large footprint | Protects property | >$1 B | Cost, open ocean access challenges, property rights |
| Green | Enhanced wetlands | Where there is an existing wetlands area that can be augmented | Reduces flooding by providing a low-lying place for water to go | $200 - $1 M/ac | Water quality, permitting, monitoring costs, maintenance, ecosystem impacts |
| Green | Revetments | Retention, helps maintain the storage volume, in conjunction with other measures | Improves walls of retainage | Varies based on material, depth, wall height | Land area, maintenance |
| Policy | Changes in land use | Applicable universally | Achieves flood risk mitigation by djusting permitted land use | Low but may incur private property rights conflicts and litigation | Private property rights conflicts and litigation |
| Gray | Roadway base protection | Low-lying areas, coastal communities | Protects roads and access routes | $1 million per lane mile | Cost, adjacent properties become uninsurable |
| Policy | Enhanced elevation of buildings or land abandonment | Developers would implement this for new construction | Reduced flood risk | Varies | Potential issues with building structure or latticework, and existing homes that are not elevated |