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Expert geologists, hydrogeologists and engineering geologists, civil engineers, and environmental scientists designing and implementing solutions for a sustainable water future

water coming from a pipe into a river


Holistic, Sustainable Solutions for the Future

West Yost’s Groundwater Team is unmatched in its ability to design and implement holistic, sustainable solutions that fuse the needs of clients, the environment, and surrounding communities. Our forward-thinking scientists and environmental engineers identify problems precisely and solve them through a methodical process that weighs political, legal, and technical considerations while building consensus for ideas and solutions.

Our groundwater resources team offers a full-service approach, including:

  • General consulting in the areas of water resources, hydrology, and hydrogeology
  • Studies and planning
  • Modeling
  • Regulatory and permitting assistance
  • Designs for well rehabilitation, new municipal wells, and ASR wells
  • Watermaster services
  • Funding assistance
  • Construction phase services
  • Operations and maintenance (O&M)
  • Optimization of existing systems
  • Groundwater management plans
  • Development and application of numerical models to evaluate the hydrologic and water quality response of ground and surface waters
  • Recharge master plans and managed aquifer recharge projects
  • Salt and nutrient management plans
  • Development and implementation of monitoring plans for surface water, groundwater, and land subsidence
  • Development and implementation of data‐management systems

West Yost brings the value of understanding and knowledge gained from groundwater regulatory compliance with the Sustainable Groundwater Management Act (SGMA) and Groundwater Sustainability Agency (GSA) formation; groundwater modeling and aquifer evaluations; and planning and design of facilities that best meet your long-term goals of quantity, quality, and conjunctive use supply strategies. In addition, West Yost staff apply construction and O&M knowledge to the design process to improve construction document quality and reduce construction risks, costs, and delays.

Project Highlights

Map of the Chino Basin

Development and Application of High-Resolution Models to Recalculate the Chino Basin Safe Yield and Follow-on Model Applications

Chino Basin Watermaster

The Chino Basin adjudication was settled in 1978 through a stipulated agreement. Through other agreements, the Chino Basin Watermaster was required to recalculate the safe yield and other hydrologic items in 2011. Our groundwater team developed and implemented a methodology based on scientific principles and detailed numerical models to develop a complete hydrologic description of the Chino Basin over the 1960-2011 calibration period and the 2012-2071 planning period.

Colusa Subbasin Groundwater Sustainability Plan and SGMA Technical Support Services

Colusa Groundwater Sustainability Agency and Glenn Groundwater Sustainability Agency

At nearly three-quarters of a million acres, the Colusa Subbasin is the largest groundwater basin in the Sacramento Valley and the eighth largest in California. Building on our years of experience with groundwater in the Sacramento Valley, West Yost has become a valued member of a multi-consultant team responsible for development of the Groundwater Sustainability Plan (GSP) for the Colusa Subbasin. We are involved in all aspects of GSP development, including engaging with stakeholders and the public, and have the primary responsibility for producing the GSP for the Colusa Groundwater Sustainability Agency (GSA) and Glenn GSA.

Development and Implementation of a Salt and Nutrient Management Plan for the San Juan Creek Watershed

South Orange County Wastewater Authority

In May 2009, the State Board adopted a Recycled Water Policy to move aggressively towards a sustainable water future by encouraging local and regional water agencies to move toward clean, abundant, local water for California, emphasizing the need to increase the reuse of recycled water in addition to water conservation, the maintenance of infrastructure, and the capture of stormwater, including dry-weather urban runoff.

Watermaster Services for Water Rights Compliance and Groundwater Management

Six Basins Watermaster

The Six Basins are a group of adjacent groundwater sub-basins located in Eastern Los Angeles and Western San Bernardino Counties. The pumping rights from the Six Basins were adjudicated in 1998 through a stipulated judgment, which established the Six Basins Watermaster (Watermaster) to implement the Judgment..

A Place-to-Play Test Well Conversion

City of Santa Rosa

As part of the City of Santa Rosa’s Emergency Groundwater Supply Program, West Yost worked with a well redevelopment contractor to rehabilitate the City’s 10-year old test well at the A Place to Play Park. Rehabilitation included: video inspection and initial pump test; swabbing and brushing; chlorination; airlift redevelopment; and pumping redevelopment; followed by a final pump test and video inspection.

Monitoring for Impact of Groundwater Management Plans on Critical Riparian Habitat

Chino Basin Watermaster and Inland Empire Utilities Agency

The Chino Basin is a large alluvial groundwater basin in Southern California with storage exceeding five million acre-feet. Groundwater in the Chino Basin generally flows from the forebay regions in the north towards the Prado Flood-Control Basin in the south (Prado Basin).

Team Spotlight

Our groundwater experts include specialists in geology, hydrogeology, engineering geology, civil engineering and water treatment plant operators. We provide over 150 years of combined experience. Meet some of our team below and on our project pages.

Samantha Adams

Groundwater Business Sector Leader

Mark Wildermuth, PE

Principal III

headshot of employee Ken Loy, PG

Ken Loy, PG, CEG, CHG


Available Positions

Scientist / Geologist I/II

Any office

Engineering | SCIEN001139


The Staff Scientist will work with a team of experienced hydrogeologists, engineers and environmental scientists on a variety of groundwater-related projects and investigations. The candidate will be expected to support technical work on more than one project simultaneously, work collaboratively with peers, and manage tasks with creative problem-solving skills and flexibility.

Insights & Trainings

West Yost is an Equal Opportunity Employer

EEO Policy