Central Coast Branch Meeting


"Vertical Flow, Faults and MODFLOW - Groundwater Model Development for the Oxnard Coastal Plain"

 Presented By:

Dr. Jason Sun, PE 
United Water Conservation District 


John Lindquist, PG, CHG 
United Water Conservation District 



The severe drought from 2012 through 2015 has caused groundwater levels to reach historic lows in coastal Ventura County, California. The recent drought is part of a repeated pattern in Ventura County, similar to the rest of southern California. United Water Conservation District (UWCD), the Fox Canyon Groundwater Management Agency (FCGMA), and other agencies tasked with management of the groundwater basins of the Santa Clara River Valley and the Oxnard Plain of Ventura County (“study area”) have wrestled with groundwater sustainability for many decades. The variable duration and magnitude of recurring wet and dry periods underscores the importance of planning groundwater management. Prior to the promulgation of the Sustainable Groundwater Management Act (SGMA) in 2014, UWCD and FCGMA recognized the importance of a detailed groundwater model to their missions.  As a result, UWCD has developed a detailed groundwater flow model to simulate aquifer-specific heads within each of the sub-basins in the current study area (the Oxnard Plain, Pleasant Valley, and Mound basins).

The hydrostratigraphy and relevant structural geology underlying the Oxnard Coastal Plain reveal that there are 13 principal hydrostratigraphic units: 7 aquifers and 6 aquitard layers. The upper aquifer system (UAS) includes three aquifers: the semi-perched, Oxnard and Mugu Aquifers. The lower aquifer system (LAS) includes four aquifers: the Hueneme, main (upper) Fox Canyon, basal Fox Canyon, and Grimes Canyon Aquifers. The UWCD model treats all 7 aquifers and 6 aquitards as individual model layers. The groundwater model uses the time period from January 1985 to December 2012 for model calibration and the time period from January 2013 to December 2015 for model validation. This calibrated groundwater model characterizes flow both between aquifers within the individual sub-basins and between the sub-basins, providing insight into the complex interaction of the regional groundwater flow. The model has been used by UWCD to evaluate travel times and distances for recharge of recycled water, and to evaluate impacts on groundwater supply resulting from a range of potential future operational scenarios for surface water diversions from the Santa Clara River.



Dr. Jason Sun is the senior groundwater modeler at United Water Conservation District. Dr. Sun is a Professional Engineer and earned his PhD from Massachusetts Institute of Technology. Prior joining UWCD, Dr. Sun had 15 years of experience working for consulting firms on groundwater related projects ranging from remediation, water resources to litigation.   At UWCD, Dr. Sun’s emphasis has been on the construction and calibration of a new groundwater flow model that ultimately will encompass the groundwater basins along the Santa Clara River, the Oxnard Plain, and the West Las Posas basin.

John Lindquist has been a Senior Hydrogeologist for the United Water Conservation District in western Ventura County since June 2015, and is a California Professional Geologist and Certified Hydrogeologist.  He holds a BS degree in Geology from CSU Northridge, and a MS degree in Geosciences (with an emphasis in Geohydrology) from the University of Arizona.  His career began with a focus on modeling of groundwater supply and recharge projects in Arizona and Chile, and subsequently expanded to include groundwater contamination and remediation projects in southern California and Turkey.  John’s recent work at United has been focused on planning for implementation of the Sustainable Groundwater Management Act in the groundwater basins of the Oxnard coastal plain, and evaluation of potential impacts on groundwater supply and quality resulting from potential changes in volume of surface water applied in the region and planned introduction of recycled water at United’s spreading grounds.


Scholastic Sponsorship Program:  The Central Coast Branch initiated a scholastic sponsorship program, with local sponsors supporting our annual scholarship fund for students who are engaged in groundwater studies. If your organization is interested in participating as a Scholastic Sponsor for a future event, please contact a Branch Officer.  Sponsors will be recognized at our meetings and on the GRA website.

Sponsors :   If you would like to sponsor a GRA Meeting or other event, or volunteer your time or services to any one of the many GRA-sponsored activities, please contact Dan Detmer at dand@unitedwater.org or (805) 525-4431. Presently, we are in need of sponsorship or donations for our upcoming meetings.  Our sponsorship program has two levels:

 A contribution of $100 will earn your company a mention in our meeting announcement as well as an opportunity to distribute information regarding services or products at our meeting.

A contribution of $300 or more your organization will be allotted 10 minutes to speak to the group and acquaint them with your services or products and the opportunity to distribute information. 

The GRA branch welcomes any ideas for sponsorship that you may have.



6:00 - 6:15 p.m. - Registration & Networking
6:15 - 7:00 p.m. - Dinner, Announcements & Business Meeting
7:00 - 8:00 p.m. - Keynote Speaker



Costs and menu are shown below. GRA is unable to assure food and room for you without an RSVP. Using GRA's automated RSVP process is quick and painless!


Meeting costs are:
Members: $35.00
Non-Members: $45.00
Students: Free (Must RSVP)

*Retired professionals receive a 10% (rounded to the nearest dollar) discount on any meal.

 If you RSVP after Noon on Friday, December 2nd, or walk-in, a $3.00 surcharge will be added to the meeting costs. Cancellations must be made by Noon on Friday, December 2nd.  At that time, we must submit a final head count and we will be charged accordingly.  If you cancel after that time, or are a no-show, we will ask you to pay the cost of your meal(s). Thank you for your cooperation. 


 Contacting the Central Coast Branch Officers: 

If you have questions, comments, or would just like to contact one of the Central Coast Branch officers, you will find them at the following addresses:

President -- Tony Morgan
United Water Conservation District

Vice President – Jeff Kubran
Dudek, Inc.
(805) 963-0651
Secretary – Bryan Bondy
Calleguas Municipal Water District
(805) 579-7196
Treasurer – Dan Detmer
United Water Conservation District
(805) 525-4431


Location Files


Tue, Dec. 6, 2016
6:00 p.m. - 8:30 p.m.

Event has ended


United Water Conservation District
106 N. 8th Street
Santa Paula , California 93060