This rainwater harvesting system marks the installation of the first of many best management practices (BMPs) for the Cypress Creek Watershed Protection Plan (CCWPP). It is a critical watershed protection BMP since it protects the local aquifer by reducing groundwater demand.The rainwater harvesting system is installed at the Patsy Glenn Refuge in Wimberley. 

What Was it Designed for?

It was designed to provide irrigation water for the butterfly garden at the Patsy Glenn Refuge during the seven-month period from April through October to keep plants in bloom during the dry summer months. The Wimberley Birding Society, which created the Patsy Glenn Refuge, recognizes the importance of protecting the aquifer while also developing the landscape of the natural area.  They decided to replace the aquifer supplied irrigation system for the butterfly garden with a rainwater harvesting system to eliminate demand on the aquifer. This rainwater collection structure and harvesting system was designed and installed to achieve this goal. 

How Much Water Can it Collect?

The system can collect up to 192 gallons of rainwater from the 16’ x 20’ roof for every inch of rainfall.  The three 500-gallon plastic tanks connected in tandem can store up to 1500 gallons at a time.  If future monthly rainfall amounts match historical averages, this system can provide up to 800 gallons of irrigation water per month from April through October, assuming that the tanks are full at the end of the winter. 

The butterfly garden that this harvesting system provides water for is located downhill of the storage tanks, so rainwater is delivered by gravity rather than the implementation of pumps or other mechanical devices.