26 February 2012

Plants and Stormwater - Cleaning Urban Runoff

Plants provide many benefits to the Urban Core city areas.  Carbon sequestration, oxygen production, nutrient uptake, urban heat island effect moderation, habitat creation, landscape beauty creation are all benefits of having plants grow in the Urban Core.

City plants are exceptionally effective in cleaning stormwater,  capturing trash, filtering nitrogen, phosphorous and toxic heavy metals.  Cleaning stormwater before the runoff reaches creeks, rivers and oceans is important.  At stake is the continued health of not only aquatic life, but the health of the entire planet.

Plants surrounding stormwater pipes filter out trash and nutrients
Plants provide habitat, sequester carbon & remove pollutants

In the above photo, stormwater runoff from the University of North Florida (UNF) parking lot drains into the swale vegetated with native herbaceous groundcovers including Frog Fruit (Phyla or Lippia), Dollarweed (Hydrocotyle) and other species.

The runoff filters into the soils and the surrounding plant roots act biologically to remove nitrogen, phosphorous and other pollutants.

During hard storms, the excess stormwater runoff overflows into a larger, wet-meadow type system.  In this system plants and trees such as Cypress, Wax Myrtle, Muhly Grass and Andropogon conduct the same nutrient uptake and evapo-transpiration processes yet on a larger scale.

Ultimately, the bio-retention system replaces open-water, mosquito breeding ponds.  The UNF system efficiently accomplishes stormwater cleansing, provides wildlife with communal habitat and foraging stock, and creates a pallet of native beauty.

Even grass and lawn can help filter and clean runoff

Plants and stormwater infrastructure can be easily integrated into Urban Core master planning.  Use of native plant species should be considered because native plants are adapted to growing in the Urban Core environments, compatible with native soils and tolerant of local weather patterns.

There are many useful publications and design manuals available on the internet including a great pdf manual about plants and stormwater published by the state of Minnesota.  

Stormwater pipes do not have to be surrounded by asphalt and concrete.  Designing infrastructure around nature's perfected filtration system using native plants can provide many benefits!


  1. Surrounding your stormwater pipes with asphalt and concrete will make the water flow faster, but we should take note that trees and grass help in absorbing water, so it is still important that the stormwater pipes are surrounded by plants and trees. That way, both the load and the pressure brought about by stormwater will be lessened, allowing the pipes to receive the water more efficiently.

  2. Looks like that construction site cleanup crew did a solid job. Thanks for sharing!