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More on Water, Irrigation and Storm Water Management

The Rain Garden Parking Lots

Rain Garden

Rain gardens are shallow depressions filled with water-tolerant plants that collect runoff and filter out pollutants before water enters the groundwater. A series of these gardens is located at the Arboretum between the main parking lots in front of the Oswald Visitor Center. The lots direct rain water to sandy soil, where salt and silt are settled out and absorbed by plants as nitrogen and phosphorous. Toxic materials picked up on the blacktop- such as oil and gasoline- are converted by bacteria within the soil into simple organic compounds and filtered with the storm water into the groundwater below.  For more information on the Arboretum's rain garden parking lot Click Here

The Storm Water Run Off Model

Storm Water Run Off Model

In partnership with the Minnehaha Watershed District and the Metropolitan Council, the Arboretum created a Storm Water Run-off Model to demonstrate on a smaller scale how rain gardens and permeable pavers work. By comparing the porosity levels of different parking lot surfaces, the model demonstrates which surfaces best absorb storm run-off. Urban developers frequently visit the model for ideas on managing their infrastructures. Click Here for more information about the Storm Water Run-off Model.  

We’re Renovating Our Irrigation


The Arboretum’s own Green Heron Pond provides 95% of our irrigation needs. To be wise stewards in using it, we’re updating our system to be more water-efficient.


NEW CONTROLS for Visitor Center Gardens - Now rain sensors stop irrigation during rain, until the soil dries. SMART controllers use weather data to manage watering for each zone’s unique soil and plants.


  • 35% savings in water use
  • No sprinklers going off in the rain or when not needed
  • Better visitor experience

NEW DRIP SYSTEM for the Nelson Shrub Rose Garden - All 549 shrub roses are now drip-irrigated by their own micro-sprinklers below the mulch. A rain sensor and SMART controller manage the watering schedule.


  • 50% less water used
  • Major savings in staff time and expenses 
  • Healthier plants because leaves stay dry and no over-watering
  • Better visitor experience


Next Step? Do an Irrigation Audit - We will conduct an audit of our entire 50-year old system and create a prioritized plan for further improving its water efficiency


The Irrigation System Renovation Project has been made possible by generous support of The Toro Giving Program, Water in Motion, and Irrigation By Design.

 Harvest Your Rain

Permanent models of rain water management for homes are on display at the Harvest Your Rain site near the Learning Center.

Picnic Shelter A: Green Roof.  A green roof installation on Shelter A demonstrates the use of a living carpet of plants to absorb significant amounts of rainfall on a normal impermeable roof surface.

Picnic Shelter B: Rain Barrels.  Linking the gutter system to a set of rain barrels provides a reservoir of water that is then available for watering plants, filling birdbaths and other outdoor uses.  

Picnic Shelter C: Rain Garden.  Managing the flow of rainwater from the roof and paved surfaces into a shallow depression filled with perennial plants that thrive in changing water levels will restore the system of natural infiltration by providing a temporary holding area where rain can soak into the soil and groundwater.


Rain Gardens/Run Off Model