What is "Stormwater"? The result of precipitation in which the water that does not infiltrated into the ground becomes surface water runoff that enters into streams and the ocean, in many cases, via the storm sewer system.
In a natural system, when stormwater either infiltrates into the ground or is absorbed by vegetation. However, when stormwater flows along an impervious surface (a hard, non-absorbing surface such as asphalt or concrete) it is called "stormwater runoff". As this stormwater moves along the land, it picks up a multitude of pollutants along the way. Pollutants include oil and grease, heavy metals, sediments, trash/debris, fertilizers, pesticides, pet waste, etc. On Oahu, stormwater runoff is usually routed off the land and into the nearest storm drain or stream and then dumped in the ocean.
Hui o Ko`olaupoko aims to treat our precious rain water as a resource rather than a waste. HOK implements projects that mimic natural systems - which capture, store and infiltration stormwater, which recharges our ground water aquifer and prevent polluted runoff from entering our streams and ocean.
Stormwater: Water that originates during a precipitation event (i.e. rain water or snow melt)
Runoff: Stormwater or water from other sources that does not soak into the ground and flows over impervious surfaces
Pervious: Allows water to pass through; permeable; absorbent (e.g. soil or grass)
Impervious surface: A hard surface such as a roof, road, parking lot or other surface that does not allow water to infiltrate causing increased surface runoff
Point source pollution: A single, definable source of pollution, such as water pollution from a waste water treatment plant discharge pipe
Non-point source pollution: Pollution that is generated by a diffused source of water (such as stormwater runoff) that carries pollutants into storm drains, streams and the ocean
Storm drains: System of drains and underground pipes that capture excess water on land and carry it underground into the nearest water body, usually a stream or directly into the ocean
Above are images of stormwater infrastructure and pollution impacts.