Department of Water Resources Home


Assessment of HMP and PL 84-99 Levees

Elkhorn Slough, Sacramento San Joaquin Delta


The general condition of the Delta levee system can be understood by determining the degree to which the levees conform to the design standards HMP (Hazard Mitigation Plan) and PL84-99 (See Levee Standards (PDF, 141 KB). However, until recently, the ability to have a "snapshot" of the entire Delta levee system was limited by the fragmentation of information available on levee conditions. The completion of a LIDAR (Light Detection and Ranging) survey and new Delta levees reference base mapping provided a way to complete a Delta-wide assessment of the levee system.

Project Description

The goal of the project was to develop individual maps and tables detailing HMP and PL84-99 compliance for all of the Delta local reclamation districts (RD), and summary results and maps for the Delta as a whole. To do this, cross sections were cut at 1000 foot intervals for all Delta islands, and topographic data was compared against idealized design prisms using GIS in order to conduct the classification. The topographic data that was used included both LIDAR data and recent RD engineer-supplied survey data, as appropriate. The RDs were also contacted for engineering input and feedback on all analysis products. The results of the assessment can be found at: