HELIX Environmental Planning (HELIX) prepared an Environmental Impact Report (EIR) for the Quarry Creek Project and a Subsequent EIR (SEIR) for the 104-acre South Coast Materials Quarry Reclamation Project located in the cities of Carlsbad and Oceanside in San Diego County. HELIX conducted preconstruction coastal California gnatcatcher and least Bell’s vireo surveys, as well as construction monitoring, noise control, and habitat maintenance and monitoring for this project to develop a 156-acre former mine into an open space and residential planned community. The Quarry Creek EIR addressed the realignment of Buena Vista Creek to the north within the mine property as approved in the 1991 Reclamation Plan and an alternative that would leave the creek in place. The 2007 amendment and associated SEIR addressed the final design for the remaining reclamation phases, including the retention of Buena Vista Creek in its current alignment. Key issues evaluated by HELIX included biological and hydrological resources related to the creek design and cultural resources associated with El Salto Falls, which have been designated as a sacred site. HELIX biologists also were responsible for the biological permitting of the project and implementation of the habitat restoration for the creek.