Sediment Resources
Here you will find tools to give you information and background to help you understand the issues related to sediment management and flood protection at Devil's Gate Dam in Hahamongna Watershed Park as well as LA County Flood Control District's Big Dig program.
Devil's Gate Dam
Arroyo Seco Flood Timeline History Reservoir Map Dam Elements
Sediment Management
Sediment Analysis - 1980 US Forest Service 'It All Flows Downhill'
Philip Williams Sediment Study - 2000 Regional Board Denial - 2011 USGS Post-fire Assessment
New Paradigm (slides) New Paradigm (video) Sustainable Sediment Management for Hahamongna
CA Alluvial Fan Task Force CA Coastal Sediment Workgroup LA County Coastal Draft Sediment Plan
Why Hahamongna Is So Special
Pasadena's Hahamongna Master Plan Save Hahamongna
Habitat Wildlife News Wetland Plant Species found at Hahamongna
Ecosystem Assessments of Hahamongna Watershed Park
Habitat Assessment of Hahamongna 2012 Arroyo Seco Watershed Assessment - 2011
USACE Arroyo Seco Watershed Ecosystem Restoration Feasibility Study
County Environmental and Planning Documents
Draft Environmental Impact Report (October, 2013)
LA County Sediment Management Strategic Plan
EIR Notice of Preparation - Sept. 28, 2011 EIR Initial Study Project Description
Original Presentation – November 2010 Biological Survey Short Term Solution
Interim Measures Public Scoping Comments - November 2011
Public Comments on the County's Draft EIR
ASF Comments Audubon Society City of Pasadena
Friends of Hahamongna Sierra Club Other Comments
Pasadena's Position
Recommentations of Sediment Working Group Sediment Working Group Slides
Final Environmental Impact Report - October 2014
No Big Lawsuit
No Big Dig Fact Sheet Lawsuit Announced Video What's Wrong with the Big Dig
Judge Chalfant's Decision - March 2017
Final EIR Revisions - July 24, 2017
Revisions Current Status Factsheet Contact Supervisors