State Route 57 Stormwater Mitigation Project

3 Documents in Project


SCH Number
Lead Agency
Caltrans, District 12 - Orange (California Department of Transportation, District 12)
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
Caltrans, District 12
1750 E 4th Street, St #100
Santa Ana, CA 92705

Phone : (657) 328-6054


33°56'23.2"N 117°52'30.9"W
Cross Streets
Northbound State Route 57 Tonner Canyon off-ramp loop
Total Acres
State Highways
Pacific Electric, Union Pacific
Multiple (5)

Notice of Completion

Review Period Start
Review Period End
Development Type
Transportation (Detention basin within off-ramp loop)
Project Issues
Aesthetic/Visual Agricultural Land Air Quality Archaeologic-Historic Biological Resources Flood Plain/Flooding Forest Land/Fire Hazard Geologic/Seismic Minerals Noise Population/Housing Balance Public Services Recreation/Parks Toxic/Hazardous Traffic/Circulation Vegetation Water Quality Land Use Cumulative Effects Climate Change
Reviewing Agencies
California Air Resources Board California Department of Conservation California Department of Fish and Wildlife, South Coast Region 5 California Department of Forestry and Fire Protection California Department of Parks and Recreation California Department of Water Resources California Highway Patrol California Native American Heritage Commission California Natural Resources Agency California Public Utilities Commission California Regional Water Quality Control Board, Santa Ana Region 8 California State Lands Commission Department of Toxic Substances Control Office of Historic Preservation State Water Resources Control Board, Division of Water Quality


Environmental Document
0Q270_DED_12   PDF 12177 K 0Q270_NOA   PDF 290 K 0Q270_Summary Form   PDF 578 K
0Q270_NOC   PDF 740 K

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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