Habitat Restoration on New Reservoir Construction

Santa Margarita Water District’s new 244-million-gallon Upper Chiquita Reservoir is the largest domestic water reservoir built in south Orange County since the 1970s.

Built on 27-acres of canyon slope, the reservoir is located in the South Orange County Sub-region Natural Community Conservation Plan/Master Streambed Alteration Agreement/Habitat Conservation Plan (NCCP/MSAA/HCP) and San Juan Creek and Western San Mateo Creek Watershed Special Area Management Plan (SAMP).

Dudek assisted the water district through the environmental planning process. When it came to habitat restoration, Dudek and the district took a seamless approach to compliance monitoring and post-construction restoration.

“Integrating restoration design, environmental compliance monitoring and restoration implementation into a seamless habitat mitigation process saves time, money and helps establish the factual record needed for agency sign-off on restoration,” said Stuart Fraser of the Dudek habitat restoration team.

Examples of habitat restoration activities that promoted both construction-phase environmental compliance as well as planned restoration included:

  • Coordinating with the district and contractor on strategies for onsite resource preservation, including avoiding sensitive vegetation, preserving soil and scheduling construction activities around seasonal restrictions.
  • Ensuring that final grading mimicked natural pre-construction contours and/or conformed to the requirements of the approved restoration plan.
  • Salvaging native seed and plants prior to site construction for use in post-construction restoration.
  • Salvaging and storing topsoil by habitat type prior to construction disturbance. This preserved the existing native seed bank, appropriate topsoil micronutrients and physical soil properties.
  • Ensuring that temporary erosion control seed mix derives from site-appropriate native plant palettes. This gets a head start on slope stabilization during restoration by enhancing first-level growth of native plants.

This step also promotes compliance with the Regional Water Quality Control Board General construction permit and can accelerate the schedule for filing a Notice of Termination. It can reduce or eliminate the need to reapply seed mixes during restoration for initial native establishment.

Fraser said construction costs can be reduced by integrating habitat restoration into the project through proper pre-construction planning and phased mitigation implementation.

Making the habitat restoration plan part of the project design assists in resource agency buyoff and securing the necessary environmental permits. For example, successful wetland restoration is promoted by integrating project drainage into mitigation area hydrological requirements. Native grassland restoration requires specific soil textural requirements best provided through on-site salvage. Native plant salvage and onsite seed collection fulfill requirements for locally appropriate genetic stock and reduces the need for repeated supplemental seeding.

“Successful mitigation begins during project design and should be integrated with all phases of project construction,” Fraser said. “This approach reduces potential stringent permit requirements, eliminates potentially redundant resource agency permitting processes, eliminates redundant construction tasks, and promotes the ultimate success of the habitat restoration effort.”