
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.
Our team developed the Hydrogeologic Conceptual Model (HCM), defined historical groundwater conditions, established the proposed monitoring network, evaluated and recommended the integrated hydrologic model, and assessed existing data and data gaps as part of GSP development. In addition to preparing GSP content, the West Yost team is currently planning additional hydrogeologic investigations to fill identified data gaps and providing ongoing support to the GSAs during development of sustainable management criteria, consideration of management areas, and identification of projects and management actions that will protect the valuable resources of the Colusa Subbasin.
Team Spotlight

Ken Loy, PG, CEG, CHG
Hydrogeologist

Ken Loy, PG, CEG, CHG
Hydrogeologist
“As a specialist in groundwater-related issues, I greatly enjoy being a part of the strong multidisciplinary teams needed to address wide-ranging client needs. Each client is unique, and each project has its own set of challenges. I enjoy learning about the client’s perspectives on these challenges and coming up with the right approach and team to address them. At West Yost we have the internal resources and team atmosphere that really makes the difference, not just within our groundwater and hydrogeology team, but across the board for water-related services. When it suits our client’s needs, we don’t hesitate to extend that collaborative team-based approach to our teaming partners. It’s great to be a part of these win-win situations!
I am especially proud to be a part of the multidisciplinary teams working to meet a variety of needs for our clients. My clients include agencies such as the Glenn and Colusa GSAs and the Santa Clarita Valley Water Authority as well as municipal clients, such as Sacramento Suburban Water District and the Cities of Davis, Dixon, Vacaville, Milpitas, Modesto, Pasadena, Petaluma, Santa Rosa, and Woodland. We have a long history of providing a variety of planning, modeling, design, and construction management services across multiple disciplines, including water and wastewater services, and it’s very gratifying to know that what I do related to groundwater is part of a bigger picture for our clients, our communities, and the sustainability of our environment.”

Anna Reimer, PG
Associate Geologist I

Anna Reimer, PG
Associate Geologist I
“I really enjoy working in the subsurface, looking at what is beneath our feet, the water there, where it is coming from, and where it is going. It is really exciting when we get projects that combine different task types. For example, projects that include or lead to a conceptual study or basin assessment, well construction and testing, groundwater modelling, management planning, and implementation. It is great being able to provide our clients insight regarding how everything is connected and assisting them with identifying beneficial future projects. I enjoy working as a consultant because we get a wide variety of task types that cross different industry sectors.
Recently, I have been working a lot on the development of the Colusa Subbasin GSP, partnering with other consulting firms. This is my first major project for which I am the primary writer of our content. The process has been challenging, but I’m pretty proud of what we have accomplished.”

Peter Dellavalle, PG
Geologist II

Peter Dellavalle, PG
Geologist II
“I get jazzed by taking data we collect and telling a story in maps and figures that illustrates to an every-day user what we learned. I get tremendous satisfaction from creating well-crafted images from dense spreadsheets of raw data. For example, for the Colusa project because we
gotstarted with a pile of data and we turned it into maps in a large report that told a story for stakeholders and the general public. It makes the information approachable and understandable.
One of my most rewarding efforts was for the City of Modesto’s Grogan Park Municipal Supply Well. It’s cool to put a big pipe in the ground and get water out of it! It worked exactly as intended, we got clean water at the volume they needed. After that, the City asked us to support them by doing two more projects, the Del Rio Well and Replacement Well 229. They were very happy with all three projects.”