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South Santa Rosa Vernal Pool Mitigation Bank

Sonoma County, CA

Vernal Pool Technologies
Fall 1999

This project, designed by Marco Waaland, Golden Bear Biostudies of Santa Rosa, constructed a series of vernal pools and swales on a 12-acre parcel located on the Santa Rosa Plain, south of the City of Santa Rosa. Historically, vernal pools that existed on this site were leveled for orchards; therefore the goal of this project was to return the native topography. Fedco, Inc. of Santa Rosa provided rough grading, which was monitored by Golden Bear Biostudies and Hanford ARC.

Following rough grading, Hanford ARC completed a number of specialized tasks for the project which included fine grading (0.10-foot tolerance) to achieve optimal pool and swale depth, topsoil harvesting and spreading, soil preparation, and hydroseeding. The topsoil harvesting method required scraping small bands of soil two inches in depth from adjacent ‘donor’ pools. This soil contains seed of native vernal pool plant species as well as eggs and dormant or aestivating macroinvertebrates. It has been demonstrated that spreading this soil in restored vernal pools with proper hydrology increases probability of successful establishment of native plant and animal species.

Hanford ARC also provided consultation on vernal pool construction methods.

Click on thumbnail to see enlarged photo.

Scarifying method

Laser level and fine graded pools

Finished vernal pool, first season

Finished vernal pool, first season

Finished vernal pool, first season