Water Smart Development and LID Guidebook

Horizon Water and Environment (Horizon) assisted the Sonoma County Water Agency (SCWA) to develop a state-of-the-art guidebook to educate and encourage the communities of Sonoma County to implement water smart development practices.  The Guidebook provides water smart development standards and BMPs for multiple objectives including water conservation, water reuse, and stormwater and runoff management.  It is envisioned that these standards and BMPs will be applied internally to support Agency operations, and applied externally to guide development projects in Sonoma County.

Low Impact Development (LID) stormwater avoidance and reduction approaches are incorporated into the Guidebook to comply with new requirements of the NPDES municipal stormwater permit for which SCWA, the City of Santa Rosa, and Sonoma County are co-permittees.  Horizon developed an LID approach that highlights site assessment and opportunities and constraints analysis to identify, apply, and design suitable LID treatments for existing and new development projects. Within the Guidebook, a range of LID treatments including biofiltration swales, permeable paving, green roofs, and rainwater harvesting are described in detail with illustrated “fact sheets.”  The Guidebook also considers other stormwater management approaches beyond the immediate site-scale measures of typical LID treatments. These include off-site runoff management approaches and regional multi-objective detention facilities that can provide runoff reduction, sediment settling, pollutant treatment, groundwater recharge, and habitat benefits.

The integrating principle of the Guidebook is that development potentially affects all aspects of the hydrologic cycle, and not just heightened runoff through increased impervious surfaces. The Guidebook describes methods to reduce water demand and opportunities to reuse water.  Taken together these smart water use strategies in addition to on-site stormwater reduction and off-site runoff management provide an integrated plan to avoid and reduce impacts throughout the hydrologic cycle.

Horizon worked closely with representatives from the North Coast Regional Water Quality Control Board, as well as each of the incorporated cities in the county to develop the Guidebook.