The water quality inventory includes the current Treatment BMP Types listed below. To see individual BMPs, visit the Find a BMP page.

Bioinfiltration (bioretention with underdrain)

Landscaped shallow depressions that normally consist of a ponding area, mulch layer, planting soils, plants, and collection pipes in a gravel layer to capture and filter stormwater runoff. A detailed description of this BMP type can be found in the BIO-1 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the INF-4 Fact Sheet for the 2011 TGD for North Orange County.
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Bioretention with no Underdrain

Landscaped shallow depressions that normally consist of a ponding area, mulch layer, planting soils, and plants to capture and infiltrate stormwater runoff. A detailed description of this BMP type can be found in the INF-3 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
54
Bioretention with Underdrain and Impervious Liner

Landscaped shallow depressions that normally consist of a ponding area, mulch layer, planting soils, plants, and collection pipes in a gravel layer to capture and filter stormwater runoff while preventing infiltration with an impervious liner. A detailed description of this BMP type can be found in the BIO-6 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the BIO-1 Fact Sheet for the 2011 TGD for North Orange County.
22
Catch Basin / Inlet (unscreened)

This BMP Type is used to track Catch Basins that do not have a trash screen installed.
3509
Cistern for Harvest and Use

Collect and temporarily store runoff from rooftops for later use as irrigation and/or other non-potable uses. This can include above-ground and below-ground systems. Cisterns can have a portion of volume dedicated to harvested water storage and a portion dedicated to detention with surface discharge. A detailed description of this BMP type can be found in the HU-1 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
6
Constructed Wetland

A system of shallow pools (1 to 2 feet deep) planted with emergent vegetation, deeper areas or micro pools (3 to 5 feet deep), and a water quality outlet structure. A detailed description of this BMP type can be found in the BIO-9 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the BIO-5 Fact Sheet for the 2011 TGD for North Orange County.
4
Dry Extended Detention Basin

Basins whose outlets have been designed to detain the stormwater quality design volume, SQDV, for 36 to 48 hours to allow particulates and associated pollutants to settle out. A detailed description of this BMP type can be found in the BIO-4 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the BIO-6 Fact Sheet for the 2011 TGD for North Orange County.
77
Dry Weather Treatment Systems

A system designed to treat dry weather flows using active treatment processes such as ultraviolet (UV) and ozone disinfection. Bacteria disinfection is the primary treatment process these systems provide. Design components typically include a diversion, pump station, (optional pre- filtration), and disinfection system.
3
Drywell

Small excavated pit filled with aggregate or a prefabricated storage chamber or pipe segment designed to temporarily store and infiltrate runoff. A detailed description of this BMP type can be found in the INF-4 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the INF-5 Fact Sheet for the 2011 TGD for North Orange County.
32
Flow Duration Control Basin

Basins that are used to control the timing and volume of runoff.
2
Flow Duration Control Tank

Tanks that are used to control the timing of runoff.
57
Hydrodynamic Separator

Pretreatment units designed to remove trash, debris, and coarse sediment using screening, gravity settling, and centrifugal forces generated by forcing the influent into a circular motion. A detailed description of this BMP type can be found in the PRE-1 Fact Sheet for the 2011 TGD for North Orange County.
312
Infiltration Basin

Earthen basin constructed in naturally pervious soils with a flat bottom and dryland grasses or irrigated turf grass to infiltrate stormwater. A detailed description of this BMP type can be found in the INF-1 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
25
Infiltration Trench

Long, narrow, rock-filled trench with no outlet other than an overflow outlet. Runoff is stored in the void space between stones and infiltrates through the bottom and sides of the trench. A detailed description of this BMP type can be found in the INF-2 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
75
Inlet and Pipe Screens

Inlet screens, baskets, and connector pipe screens installed within a catch basin to capture trash. This BMP can also be used to inventory catch basins without screens or baskets.
9299
In-stream Trash Capture

Manufactured units that contain a floating removable boom or basket that collects floating debris/litter within the channel.
7
Low Flow Diversion

Designed to divert dry-weather runoff from storm drains into the sanitary sewer or other endpoint to eliminate discharge into receiving waters.
50
Natural Treatment Systems

A system of shallow pools planted with emergent vegetation, deeper areas or micro pools, and a water quality outlet structure. Natural Treatment Systems (NTS) can be designed to treat dry weather flow only or both wet and dry weather. This BMP type is specific to the San Diego Creek Watershed NTS Master Plan. It is not currently in the Technical Guidance Document (TGD). It is most similar to Constructed Wetlands (BIO-9) in the TGD. It can be referenced as BIO-10.
1
Permeable Pavement

Designed as modular paving system (concrete pavers, grass-pave, or gravel-pave) or poured in place pavement (porous concrete, permeable asphalt) containing small voids that allow water to pass through to a gravel base. A detailed description of this BMP type can be found in the INF-5 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the INF-6 Fact Sheet for the 2011 TGD for North Orange County.
116
Proprietary Biotreatment

Devices that are manufactured to mimic natural systems such as bioretention areas by incorporating plants, soil, and microbes engineered to provide treatment at higher flow rates or volumes and with smaller footprints than their natural counterparts. A detailed description of this BMP type can be found in the BIO-7 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
431
Proprietary Treatment Control

Manufactured devices that treat stormwater and usually include filtration through engineered, proprietary media mixes and/or filtration through cartridge filters. A detailed description of this BMP type can be found in the TRT-2 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
1282
Sand Filters

Designed to filter stormwater through a constructed media bed (generally sand) with an underdrain system. A detailed description of this BMP type can be found in the TRT-1 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
6
Underground Infiltration

Vault or chamber with an open bottom used to store runoff and percolate into the subsurface. Proprietary vendors offer products that allow for similar or enhanced rates of infiltration and subsurface storage while providing durable prefabricated structures. A detailed description of this BMP type can be found in the INF-6 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the INF-7 Fact Sheet for the 2011 TGD for North Orange County.
19
Vegetated Filter Strip

Designed to treat sheet flow runoff from adjacent impervious surfaces or intensive landscaped areas. Filter strips decrease runoff velocity, filter out total suspended solids and associated pollutants, and provide some infiltration into underlying soils. A detailed description of this BMP type can be found in the BIO-3 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
43
Vegetated Swale

Open, shallow channels with low-lying vegetation covering the side slopes and bottom that collect and slowly convey runoff flow to downstream discharge points to provide pollutant removal through settling and filtration. A detailed description of this BMP type can be found in the BIO-2 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the 2011 TGD for North Orange County.
264
Wet Detention Basin

Constructed, naturalistic ponds with a permanent or seasonal pool of water maintained by outlet controls and base flows exceeding or matching losses through evaporation and/or infiltration. A detailed description of this BMP type can be found in the BIO-8 Fact sheet in the 2017 Technical Guidance Document (TGD) for South Orange County or the BIO-4 Fact Sheet for the 2011 TGD for North Orange County.
2