A rain garden is a vegetated filtration and/or infiltration system that has a contributing drainage area not to exceed two acres, and a ponding depth not to exceed twelve inches.
Unlike conventional centralized stormwater management systems, rain gardens may employ multiple controls dispersed across a development, and may be incorporated into the landscape to provide aesthetic as well as ecological benefits.
Rain gardens can be designed to provide a level of treatment equivalent to sedimentation/filtration, and also provide extended detention that enhances baseflow and reduces stream erosion.
Rain Garden FAQs Can rain gardens be used in the Barton Springs zone as a stand-alone water quality control?
No – Rain Gardens are not allowed in Barton Springs Zone (BSZ)watersheds as a stand-alone water quality control, as they are not capable of achieving a non-degradation level of treatment. The use of a Rain Garden as a water quality control is limited to Commercial and Multi-Family developments only.
Are rain gardens eligible for landscape credit?
Yes - Because of the vegetation, rain gardens can be aesthetic amenities and may be eligible for landscape credit (unlike sedimentation/filtration systems).
What is an IPM plan?
IPM stands for Integrated Pest Management. To ensure proper management of the pond system, filtration media, and vegetation, an Integrated Pest Management (IPM) Plan is required. www.austintexas.gov/ipm
Where can I find design guidelines?
Design guidelines for rain gardens can be found in Section 1.6.7.H of the Environmental Criteria Manual. Click here for guidelines and resources for small scale green stormwater infrastructure.
Where can I learn more about biofiltration media?
The rain garden filtration media is the same as that used for biofiltration systems. For information on the biofiltration media go to the Biofiltration Media guidance document.
Where can I find a list of potential biofiltration media suppliers? Click here for a list of potential biofiltration media suppliers