Caltrans District 1 - Surface Water Quality Monitoring Program - Willits Bypass Project

High-flow stream gauging with ADCP raft for safe and accurate development of head to flow rating curves.
Monitoring site selection prioritized safe access, steam representativeness, and equipment security.
Time-series physical parameters and water quality data collection to establish baseline trends.
Client: 
California Department of Transportation (CalTrans)
Prime Contractor: 
IFC International
Brown and Caldwell
Location: 
Willits, California
Period of Performance: 
July, 2010 to July, 2012
January, 2016
Project Description: 

As mandated by the Clean Water Act Section 401 permit approved by the North Coast Regional Water Quality Control Board, Caltrans implemented a yearlong baseline monitoring study to characterize the water quality and stream flow rates within the watershed of Outlet Creek in Little Lake Valley. For this project, 20 monitoring sites were designed and installed by ADH. Sites consisted of: creating safe access to the location; long-term deployment of continuous monitoring multi-parameter water quality sondes; fabrication of protective sonde casings; installation of water-level loggers housed in custom fabricated stilling wells; installation of staff gauges and establishment of benchmarks; fabrication of solar shields and installation of air temperature loggers; installation of rope transect lines across streams for current meter deployment during high-flow stream gauging.

ADH performed monthly collection of water quality samples, equipment maintenance/storm damage repairs, data downloading, sonde calibration, high stream flow measurements, and secured encroachment permits for county bridges. High stream flow measurements were performed using an acoustic doppler current profiler (ADCP) programmed and controlled by a wireless hand-held unit. ADH staff participated in eight storm event sampling events annually.

ADH Responsibilities: 
  • Site selection
  • Secure bridge access encroachment permits
  • Design, procure materials and fabricate protective sonde casings, stilling wells, and solar radiation shields
  • Install and maintain stilling wells and staff gauges, water quality meters, water level loggers and air temperature loggers
  • Perform  routine monthly water quality grab sampling
  • Perform eight storm sampling events
  • Perform high flow stream ratings
  • Develop flow rating curves
  • Prepare maintenance technical memoranda
  • Quality assurance/quality control
  • Spawning gravel monitoring and sampling

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