Bioswales Filters Polluted Water Saving Rivers & The Ocean

Street-drain-bioretention-cell-basin-example

Bioretention cells and Bioswales Filtering Stormwater Runoff


Bioswales are designed to remove pollutants and silt from surface runoff water. Natural areas consist of a marshy runoff course, gently sloped sides, and are filled with plants, compost and, in some cases, rocks known as riprap bioswale removes pollutants and silt by maximizing the time water spends in the swale, which aids in trapping and filtering pollution at its source and before it enters rivers or the Ocean.

One of the most common locations for a bioswale is next to a parking lot. e parking lot collects pollution from cars and rainwater flushes the lot into a bioswale. e bioswale then filters the water and releases the cleansed water into the storm drain system or a local waterway.

Other cities like Portland, Oregon are doing a great job at utilizing bioswhales portland to lower pollution runoff water and the collections of cigarette butt litter leaving plastic filters in our waterways and watersheds we depend on so much. 

Bioretention cells and bioswales help filter water before polluted runoff water flows into rivers or the Ocean. Small pond like designs called Bioretention cells or Swales are treatment devices for stormwater, which generally occur in public spaces. They infiltrate stormwater but this is not their primary purpose.

Moisture levels fluctuate widely in these features, since the flow of water they receive is concentrated, sometimes up to 40 times what a given area would receive naturally.

Tight clay subsoils in our region, these features normally include a subdrain system that ultimately ties to the storm sewer system. Water passes through the soil where physical, chemical and biological processes break down, filter, or hold contaminants. Water that reaches the subdrain is far cleaner, its temperature is moderated, and the flow rate and volume are attenuated. Suspended pavements which receive stormwater inputs function in the same way.


There is a lot of confusion over the terminology and overlap between bioretention, biofilter, bioswale, and rain garden. The ALIDP takes the approach that the term bioretention should be used to indicate the highly engineered feature, generally occuring in the public realm, where treatment is the primary function. The term rain garden should be used when describing depressions, typically on residential lots where downspouts are directed into them, receiving about four times the normal amount of moisture, where volume attenuation is the primary function.

Designers have long known the toll that compacted turf-and-tree landscapes and hardened surfaces like roofs, roads and parking lots take on our lakes, rivers and streams. However, the tools to address these impacts in this complex system have only begun to be developed in the past decade or two.

Green infrastructure, sustainable urban drainage systems, water-sensitive urban design, low impact development…whatever the name, the goal remains the same: a high-performance urban environment from the perspective of our water resources.

Maps of Bioretention Cell examples and map of  Oregon State University Bioretention Cell Campus Locations, you should learn about. 

What is a Rain Garden

What is a rain garden and why would are needed? Rain gardens for your viewing pleasure. Being aesthetically attractive is one of the many great reasons for rain gardens but the main functions are their impact on our living environment! Rain gardens are vegetated depressions that catch rain runoff from impervious areas such as roofs, driveways, walkways, parking lots, and even some compacted lawn areas. e rain runoff is captured in the gardens and allowed to soak into the soil.

The pond like areas replace concrete areas slowing down runoff water and prevents surges of rain water from flowing into storm drains or local streams which causes erosion, water pollution, flooding, and diminished groundwater. e essential purpose of a rain garden is to improve the water quality in nearby bodies of water.

Think of all the oil drips in parking areas