HELIX Environmental Planning (HELIX) provided environmental compliance monitoring during construction and during the post-construction phase of the Carlsbad Oaks North Project, a 414-acre master planned corporate business park. HELIX monitored air quality, water quality, and biological resource mitigation measures in accordance with the Carlsbad Oaks North EIR. HELIX wrote water quality monitoring plan and conducted sediment/siltation monitoring, water quality assessments, and benthic macroinvertebrate community analyses. Biological resource monitoring included construction monitoring, compliance with the project’s Mitigation, Monitoring and Reporting Program (MMRP), Storm Water Prevention Pollution Plan (SWPPP) monitoring, and a 7-year functional assessment of habitat adjacent to the construction site. HELIX staff helped ensure implementation of Clean Water Act Section 404 permit, Clean Water Act Section 401 certification, and California Fish and Game Code Section 1602 Agreement conditions. HELIX also conducted vegetation mapping, focused surveys for coastal California gnatcatcher, monitoring of geotechnical testing, and habitat restoration and monitoring of wetland and upland habitats.