Water Quality Modeler Jobs (NOW HIRING)

Larry Walker Associates is seeking a Groundwater Modeler to support numerical modeling and technical analysis on groundwater projects throughout California. This role is suited to candidates with more than 4 years of professional experience who are passionate about groundwater modeling and want to apply their expertise across a range of complex projects. The successful candidate will work with teams to develop and apply groundwater models in support of SGMA compliance, basin characterization, water resources planning, and regulatory reporting.

• Develop, calibrate, and apply numerical groundwater flow and transport models using MODFLOW (e.g., MODFLOW-6, MODFLOW-OWHM, MODFLOW-USG) and/or DWR integrated hydrologic models (IWFM, C2VSim)
• Perform model parameter estimation and uncertainty analysis
• Develop and evaluate model input datasets including hydrostratigraphy, recharge, pumping, and water quality using R or Python, specialized software, and GIS
• Conduct scenario analyses to evaluate groundwater management strategies, pumping impacts, and recharge effectiveness
• Use model outputs to support basin management, facilitate stakeholder engagement, and meet regulatory requirements
• Prepare clear and well-documented technical reports, model documentation, and presentations

• Bachelor’s degree or higher in Geology, Hydrologic Sciences, Civil/Environmental Engineering, or a closely related field
• Demonstrated hands-on experience with MODFLOW-based numerical groundwater modeling (e.g., MODFLOW-6, MODFLOW-OWHM, MODFLOW-USG, MODFLOW-NWT) or equivalent
• 4 years of professional experience in hydrogeology, or water resources engineering
• Proficiency in Python or R for scripting, data processing, and model pre/post-processing
• Strong technical writing skills with the ability to document model construction, calibration, and results clearly for both technical and regulatory audiences
• Willingness to travel as needed

• Experience with IWFM, C2VSim, or other integrated surface water–groundwater modeling frameworks used by DWR
• Familiarity with California water data systems (DWR, GAMA, CIMIS, OpenET, DDW, CEDEN) for model input development and data validation
• Professional registration (e.g., PG, CHG, PE) in California is highly desired
• Excellent work ethic, self-directed, and highly motivated
• Valid driver's license

• LWA’s total compensation package includes a competitive salary, an annual bonus program, a fully funded profit-sharing retirement program, a full range of health benefit offerings (including medical, dental, vision, life, and long-time disability insurance), flexible paid vacation time, paid sick leave, 10 paid holidays a year, and an annual training budget which includes conference attendance and support to obtain professional licensure.
• Our company is organized into self-directed teams that provide opportunities for employees to take responsibility for their own career path, work on diverse and interesting projects, and assume leadership roles from day one. Technical staff are directly involved in project leadership, client engagement, and strategic decision-making.
• LWA is committed to our values of passion for excellence, caring, building meaningful relationships, forward thinking, and serving the public good, and our successful employees embody the behaviors that support those values. We are known for taking great care of our clients and employees alike.

Larry Walker Associates (LWA) is a small, family-owned environmental engineering and consulting firm based in Davis, California with regional offices in Berkeley, San Diego, Santa Monica, Ventura, Yreka, and Seattle. Our Groundwater team currently supports GSP implementation in 15 basins across California and has led the development of 5 GSPs, with expertise ranging from numerical modeling and groundwater recharge to basin-scale water quality planning under CV-SALTS. LWA is a Certified Evergreen® company and was recognized by the Tugboat Institute as one of the 2025 Best Evergreen Companies for our commitment to long-term purpose, a people-first culture, and sustainable growth. LWA is privately held, built to last, and focused on serving the public good, including its employees, clients, and communities. As an Evergreen® business, LWA is committed to upholding the Evergreen 7Ps® principles: Purpose, Perseverance, People First, Private, Profit, Paced Growth, and Pragmatic Innovation.

Larry Walker Associates is an Equal Opportunity Employer. Applicants are considered for all positions based on experience and education, without regard to race, color, religion, national origin, age, medical condition, physical or mental disability, marital status, sex, sexual orientation, reproductive health decision-making, genetic information/characteristics, gender, gender identity, gender expression, transgender, military or veteran status, or any other characteristic protected by federal, state, or local laws. This policy governs all aspects of employment including recruiting, hiring, job assignment, promotion, compensation, training, access to benefits, discipline, and termination.