Hydrologic Effectiveness and Plant Survivability in the Holmes Lake Rain Garden Pilot Program: Year Three

Rain gardens are increasingly being used as small scale stormwater best management practices (BMPs) to reduce stormwater runoff through infiltration and to remove pollutants through filtration. In 2007, as part of a comprehensive water quality restoration process of Holmes Lake in Lincoln, Nebraska, 20 pilot rain gardens were installed in residential and school properties in the watershed. Currently, assessment and monitoring has been limited to participant surveys and cannot be used to determine if hydraulic or vegetative problems exist within the garden area. In this study, visual inspections were conducted to establish a database standard for successful rain gardens, hydraulic and/or vegetative problems were noted, followed by interviews with rain garden owners. Of the 18 surveyed rain gardens, several issues appeared that were attributable to garden revisions by property owners. In all but three gardens, there was an overall problem with plant survivability. Issues more closely studied included use of sprinkler systems, hydraulic function, and plant placement within the garden. Plant placement appears to be a major concern relative to plant survivability. Plant lists need to be updated to include where a plant will do best within the rain garden depression and the installer needs to be further educated on these findings. This study also shows that visual inspections can be an efficient and low cost, effective way to detect problems within a residential rain garden