Water Resources Engineer III

Castillo Engineering; United States; Remote; USD 95,000 - 135,000; Full time

Benefits offered by this job

Health, dental, and vision insurance

Paid time off and company holidays

Professional growth opportunities

Job summary

A leading engineering firm in the United States is seeking a Water Resources Engineer III to design and manage utility-scale solar and battery projects. This role demands expertise in hydrologic and hydraulic modeling, regulatory compliance, and end-to-end project ownership. Candidates should possess a relevant engineering degree and have 3–5 years of experience, especially in solar projects. With a focus on mentorship and innovation, this position also allows for a remote work arrangement within the continental US.

Qualifications

• 3–5 years of experience in water resources engineering, especially in utility-scale solar.
• PE licensure or active EIT with clear path to PE preferred.
• Experience in stormwater drainage and NPDES CGP compliance.
• Proficiency in HEC-HMS and HEC-RAS; experience with StormCAD or equivalent.
• Strong writing skills; experience with drainage reports and permit applications.

Responsibilities

• Lead hydrologic and hydraulic modeling tasks.
• Manage water resource scope on utility-scale solar projects.
• Regulatory compliance for floodplain and stormwater permits.
• Stamp hydrologic/hydraulic reports and permit applications for multi‑jurisdictional submittals.
• Manage construction-phase water resources support and RFI responses.
• Mentor staff and contribute to internal standards and QA/QC.

Skills

HEC-HMS proficiency

HEC-RAS experience

Technical writing skills

Strong communication skills

Education

Bachelor's degree in civil or environmental engineering

PE licensure or EIT with path to PE

Tools

AutoCAD Civil 3D

ArcGIS or QGIS

HEC-RAS

StormCAD

ArcGIS / QGIS

Job description

Build What’s Next with Castillo Engineering

At Castillo Engineering, you will design utility-scale solar and battery storage projects that are shaping the future of energy while accelerating your own career in the process. We’re looking for a Water Resources Engineer III who thrives on meaningful project ownership, has strong communication skills, a commitment to excellence, and a passion for supporting clean‑energy projects in a process‑driven, collaborative environment.

Why You’ll Love Working Here

We are a fast-growing, mission-driven firm where engineers are trusted, supported, and given clear opportunities to advance. You will work in a collaborative environment that values mentorship, innovation, and professional growth, allowing you to develop your skills, make a visible impact, and build confidence as part of a close-knit team.

Position Overview

The Water Resources Engineer III is Castillo Engineering's subject matter expert (SME) for all hydrologic, hydraulic, floodplain, and stormwater engineering disciplines. This role operates with full autonomy across the project lifecycle—leading feasibility assessments, directing advanced hydrologic/hydraulic modeling, stamping permit packages as Engineer of Record, and guiding construction phase support. Beyond project delivery, the Engineer III owns the water resources technical practice: developing company standards, mentoring multi‑level staff, advising on tool adoption, and contributing directly to business development and strategic growth. PE licensure is required.

What You’ll Do

• Full-Cycle Project Ownership
• Own end-to-end water resources scope on utility‑scale solar and BESS projects (50 MW to 500+ MW AC), serving as Engineer of Record (EOR) for drainage reports, stormwater permit packages, and floodplain analyses.
• Lead site feasibility and fatal-flaw assessments from a water resources perspective: floodplain extent, USACE jurisdictional waters, basin drainage patterns, downstream constraints, and regulatory risk screening.
• Direct preparation of 30%, 60%, 90%, and IFC water resources deliverables, coordinating across civil, environmental, structural, and electrical disciplines with full accountability for schedule, scope, and quality.
• Stamp and seal hydrologic/hydraulic reports, stormwater design calculations, drainage plans, and permit applications for multi‑jurisdictional submittals.
• Manage construction phase water resources support: RFI responses, drainage‑related contractor submittals, field change directives, SWPPP compliance support, and as‑built documentation review.
• Proactively identify and communicate hydrologic risk, permitting schedule risk, and regulatory compliance exposure to project managers and clients.
• Advanced Hydrology & Hydraulic Modeling
• Execute and oversee complex continuous hydrologic simulation using HEC-HMS, SWMM, or equivalent tools for watershed‑scale runoff analysis, long‑term basin water balance, and flood frequency estimation.
• Lead 2D unsteady hydraulic modeling using HEC‑RAS 2D for floodplain mapping, floodway encroachment analysis, bridge and culvert backwater assessment, and FEMA regulatory submissions.
• Develop and validate calibrated watershed models integrating LiDAR terrain, soils (SSURGO), land use, and stream gauge data for high‑accuracy design and regulatory modeling.
• Evaluate climate risk factors including changes in extreme precipitation frequency, IDF curve updates, and sea level rise implications for long‑lived solar infrastructure siting and design.
• Floodplain Engineering & FEMA Regulatory Leadership
• Lead preparation and submission of Conditional Letters of Map Revision (CLOMR) and Letters of Map Revision (LOMR) including HEC‑RAS modeling packages, MT-2 form packages, and community coordination.
• Navigate no‑rise certification requirements, floodway encroachment analysis, and compensatory storage design for projects with fill within regulatory floodplains.
• Develop regulatory strategy for projects intersecting complex floodplain constraints: multiple flood zones, alluvial fan hazard areas, coastal flood zones, and areas lacking effective FIS studies.
• Coordinate with local CFMs, state NFIP coordinators, and FEMA regional offices to resolve technical review issues and advance map revision submittals.
• Stormwater Quality, Green Infrastructure & Regulatory Strategy
• Lead stormwater quality design for projects subject to stringent nutrient, sediment, or volume‑based water quality standards under state MS4, TMDL, or basin‑specific regulatory programs.
• Design and specify advanced post‑construction BMPs including constructed wetlands, bioretention systems, permeable pavement sections, and hydrodynamic separators for solar site O&M areas and access roads.
• Develop watershed‑level stormwater management strategies for large solar projects spanning multiple drainage basins, municipalities, and regulatory jurisdictions.
• Provide expert technical support for USACE Section 404 Individual Permit and Nationwide Permit (NWP) applications, including mitigation sequencing, compensatory mitigation design, and water quality certification coordination.
• Advise on MS4 Phase I and Phase II permit compliance strategies, impervious cover accounting, and post‑construction BMP long‑term maintenance programs.
• Environmental Hydrology & Ecological Flow Analysis
• Support biological resource consultations by providing quantitative hydrologic impact data to wetland specialists, biologists, and environmental permitting teams.
• Assess cumulative downstream impacts on receiving water bodies including flood stage changes, channel erosion potential, sediment loading, and thermal effects.
• Serve as Castillo Engineering's primary water resources technical contact for clients, regulatory agencies, and utility interconnection authorities across the project portfolio.
• Lead agency pre‑application meetings, regulatory strategy sessions, and technical presentations to FEMA, USACE, state WMDs, and local AHJs.
• Support business development efforts by contributing to technical proposals, scope definitions, fee estimates, and qualifications for water resources services.
• Build and maintain agency relationships across Castillo's operating footprint; proactively track regulatory changes affecting solar project permitting timelines and design requirements.
• Provide technical direction and QA/QC review for all water resources deliverables across the project portfolio; establish and enforce quality standards for hydrologic models, hydraulic analyses, and permit packages.
• Mentor Engineer I, II, and project designer staff on hydrology and hydraulics fundamentals, software proficiency, permitting strategy, and professional development.
• Facilitate internal training sessions on modeling software updates, regulatory changes, and technical lessons learned from completed projects.
• Participate in candidate interviews and technical assessments for water resources and civil engineering hires.
• Process Improvement & Strategic Contribution

What You Bring

• Bachelor's degree in civil engineering or environmental engineering with coursework emphasis in water resources, hydrology, or hydraulics.
• 3–5 years of experience in water resources engineering, with at least 2 years on utility‑scale solar, land development, or large‑site drainage projects.
• PE licensure (or active EIT with clear path to PE within 12 months strongly preferred).
• Proficiency in HEC-HMS and HEC‑RAS (1D/2D); experience with StormCAD or equivalent pipe network modeling software.
• Demonstrated experience preparing SWPPP packages and stormwater drainage reports for large‑acre construction projects under NPDES CGP.
• Working knowledge of FEMA floodplain regulations and experience supporting LOMA/LOMR submittals.
• Proficiency in AutoCAD Civil 3D for drainage plan preparation, surface modeling, and grading design.
• GIS proficiency (ArcGIS or QGIS) for watershed delineation, terrain analysis, and regulatory mapping.
• Familiarity with state‑level stormwater permitting programs; Florida WMD experience preferred.
• Strong technical writing skills; experience authoring drainage reports, permit applications, and technical memoranda.
• Experience with HEC‑RAS 2D unsteady‑flow modeling for floodplain encroachment analysis preferred
• Knowledge of post‑construction stormwater quality design standards and pollutant load reduction calculations preferred
• Familiarity with Section 404/401 permitting processes and coordination with USACE and state environmental agencies preferred
• Experience with solar project interconnection civil requirements and drainage coordination with utility owners preferred
• CPESC, CESSWI, or CFM certification preferred
• This role has a remote work arrangement anywhere in the continental US.
• Competitive salary based on experience
• Health, dental, and vision insurance (if applicable)
• Paid time off, company holidays, and professional growth opportunities
• Supportive culture committed to mentorship, innovation, and continuous improvement
• Direct voice in shaping Castillo Engineering's technical standards, service offerings, and strategic direction