State Route 57 Stormwater Mitigation Project

3 Documents in Project


SCH Number
Lead Agency
California Department of Transportation, District 12 (DOT)
Document Title
State Route 57 Stormwater Mitigation Project
Document Type
MND - Mitigated Negative Declaration
Present Land Use
Document Description
Caltrans proposes to provide long-term measures to reduce pollutant contributions to the San Gabriel River-Coyote Creek Watershed by construction of a detention basin within the northbound State Route 57 Tonner Canyon Off-Ramp loop at Post Mile 22.0 in unincorporated Orange County, California. The proposed project will construct a detention basin as a form of a treatment Best Management Practice that will connect and discharge to the existing drainage system. In addition, the proposed project will add a maintenance vehicle access road within the off-ramp, a Midwest guardrail system along the right-side of the off-ramp loop, and relocate and add additional light posts for the off-ramp.

Contact Information

Alben Phung
Agency Name
Caltrans, District 12
Contact Types
Lead/Public Agency


Cross Streets
Northbound State Route 57 Tonner Canyon off-ramp loop
Total Acres
State Highways
Pacific Electric, Union Pacific
Multiple (5)

Notice of Completion

State Review Period Start
State Review Period End
State Reviewing Agencies
California Air Resources Board (ARB), California Department of Conservation (DOC), California Department of Fish and Wildlife, South Coast Region 5 (CDFW), California Department of Forestry and Fire Protection (CAL FIRE), California Department of Parks and Recreation, California Department of Water Resources (DWR), California Highway Patrol (CHP), California Native American Heritage Commission (NAHC), California Natural Resources Agency, California Public Utilities Commission (CPUC), California Regional Water Quality Control Board, Santa Ana Region 8 (RWQCB), California State Lands Commission (SLC), Department of Toxic Substances Control, Office of Historic Preservation, State Water Resources Control Board, Division of Water Quality
Development Types
Transportation (Detention basin within off-ramp loop)
Project Issues
Aesthetics, Agriculture and Forestry Resources, Air Quality, Biological Resources, Cultural Resources, Cumulative Effects, Flood Plain/Flooding, Geology/Soils, Hazards & Hazardous Materials, Hydrology/Water Quality, Land Use/Planning, Mineral Resources, Noise, Population/Housing, Public Services, Recreation, Transportation, Vegetation, Wildfire, Climate Change


Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

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