Water Resources Engineer III

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.

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.

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.

• 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…