Water Resources

Our Mission 

The Water Resources Flood Hazard Review & Master Planning Section delivers specialized floodplain management and hydrology support to promote safe, sustainable development and effective flood control throughout the County. As part of the Water Resources Division, we serve as a trusted source of hydrology and floodplain expertise, offering technical guidance and assistance in areas such as: 

  • Drainage master planning and hydrology modeling 
  • FEMA mapping and levee certification coordination 
  • Flood hazard and environmental review near flood control facilities 

We support both the maintenance of existing stormwater drainage infrastructure and the construction of new Flood Control District facilities. Our team also reviews private development projects to ensure they comply with the District’s flood control standards and goals. 

Online Data

Flood Hazard Review & Master Planning Section 

The Flood Hazard Review & Master Planning Section is responsible for evaluating flood risks and planning long-term flood control solutions to support safe and sustainable development throughout the County. 

Flood Hazard Review 

This section reviews proposed developments to assess potential flood risks from various sources, including: 

  • Streams 
  • Channels
  • Basins 
  • Lakes 

We also evaluate how new developments may impact adjacent Flood Control District facilities. Based on this analysis, we recommend design and construction practices to help mitigate identified flood hazards. 

Key responsibilities include: 

  • Reviewing floodplain analyses prepared by consultants for both District and private projects 
  • Assessing new technologies for flood prediction and comparing them to historical data to ensure reliability and accuracy 

Master Planning 

To support regional flood management, we prepare large-scale hydrology models as part of: 

  • Master Plan of Drainage (MPD) studies 
  • Comprehensive Storm Drain Plan (CSDP) studies 

These conceptual studies focus on broad geographic areas and are used to: 

  • Guide future flood control infrastructure improvements 
  • Coordinate development planning activities 
  • Support the establishment of funding mechanisms 

While MPD and CSDP studies are not intended for project-specific design, they serve as essential frameworks for long-term planning and investment in the County’s flood control systems. 

Software Requirements for Drainage Report and Permit Applications 

For projects requiring complex hydraulic or hydrologic modeling, please adhere to the following: 

  • Accepted Hydrologic Software: 
    • Advanced Engineering Software (AES) 
    • Civil Design Software 
    • HEC-HMS (Hydrologic Engineering Center – Hydrologic Modeling System) 
    • Accepted Hydraulic Software: 
    • Los Angeles County WSPG program 
    • HEC-RAS (Hydrologic Engineering Center – River Analysis System)