Caltrans Headquarters - Stormwater Quality Monitoring Program - Areas of Special Biological Significance (ASBS)

Reference stream gauging for ambient loading calculations,  Gazos Creek
Prime Contractor: 
Period of Performance: 
April, 2005 to September, 2007
June, 2008
Project Description: 

As mandated by the State Water Resources Control Board’s (SWRCB) Draft Special Protections - Areas of Special Biological Significance (ASBS) 2006 Draft Proposal, Caltrans implemented a monitoring study to characterize the quality of stormwater runoff from Caltrans highway locations that are tributary to ASBS. Since 2006, under the 43A0127 and 43A0208 contracts, ADH has supported Caltrans as a subcontractor, primarily on the central and northern California ASBS sites.

For this complex, multi-faceted and evolving monitoring project, storm-water was collected at three edge-of-pavement (EOP) highway locations that are tributary to selected ASBS within central and northern California over three storm seasons. During the first year of monitoring, the EOP site sampling was performed concurrent with ocean receiving water sampling for one event. During the second and third monitoring years, in addition to the three EOP sites being sampled for eight events, water quality was also monitored at two reference stream sites concurrent with three of the EOP events. Annual “Interim” monitoring reports were generated to present all physical, chemical, microbiological and toxicological data with the intent that water quality of highway runoff would be respectively compared to representative ocean and reference stream receiving water quality.

The overall monitoring effort employed automated samplers and flow meters to collect event-based, flow-weighted stormwater composite samples at the EOP sites and time-based multi-day event (up to seven days) composite samples at the reference stream sites. Grab samples were collected during every event and monitored for several parameters, including low-level mercury and microbiology. In addition, water level and discharge data were measured and collected throughout the storm season, both during and between monitored events, to develop stream discharge rating curves for the reference stream sites. Automated monitoring equipment was also used to measure rainfall, storm flow rate and volume, and to communicate remotely for system control and data acquisition during and between monitored events.

ADH Responsibilities: 
  • Sampling site selection and preparation of site selection technical memoranda
  • Secured site access, encroachment and/or coastal development permits from multiple agencies including the California Coastal Commission, San Mateo County Planning Department, respective Caltrans staff, private landholders, and Native American tribes
  • Prepared the statewide (including the southern California sites) ASBS Health and Safety Plan
  • Prepared and annually revised the statewide ASBS Sampling and Analysis Plan in respect to Caltrans Comprehensive Protocols Guidance Manual and the California Oceans Plan
  • Installation, operation, and maintenance of automated monitoring equipment
  • Coordinated and conducted water monitoring at all EOP, reference stream and ocean-receiving water sites; and performed nearly flawless multi-faceted monitoring activities, often over several consecutive 24-hour days, under extremely difficult weather, surf, stream and driving conditions, particularly at the ocean receiving and reference stream sites
  • Developed and performed stream discharge measurements in accordance with U.S. Geological Survey gauging methods that included installation, operation and maintenance of water level measurement transducers at each reference stream site, and real-time flow rate transect measurements using electromagnetically-based hand-held flow meters
  • Prepared all post storm-technical memoranda
  • Provided comprehensive project quality assurance/quality control for field and laboratory results
  • Prepared all ASBS 8, 9, 15 annual interim monitoring reports; for the 2007-2008 and 2012-2013 annual interim monitoring reports, incorporated all relevant data from the two southern California ASBS located at Point Magu and along the Irvine coast (ASBS 24 and 33) EOP monitoring sites
  • Provided ongoing expert technical advisory input to Caltrans and Office Water Programs staff
  • Regularly participated in and provided technical expertise at SWRCB-sponsored northern California ASBS stakeholder’s meetings

Ocean graph sampling at Ano Nuevo Bay

Ocean grab sampling at Año Nuevo Bay