San Joaquin Council of Governments (SJCOG), on behalf of the Cities of Stockton and Tracy, is providing a DRAFT PM2.5 and PM10 Hot-spot Conformity Assessments for public review/comment and for interagency consultation. The two projects, both located in San Joaquin County, are: 1) Stockton Swain Road / Morgan Place Roundabout; and 2) the Interstate 580 / Corral Hollow Road Interchange Bridge Improvement. The San Joaquin Valley Air Basin is in non-attainment for PM2.5 and maintenance for PM10. All related materials are available for public review/comment on the SJCOG website: https://www.sjcog.org/281/Air-Quality.
The first proposed project consists of converting an existing four-way-stop-controlled intersection at Swain Road and Morgan Place to a roundabout.
The second proposed project consists of converting the existing Tight Diamond interchange into a Diverging Diamond Interchange, including widening the Corral Hollow Road Overpass (Bridge No. 29-0080) to 4 lanes and adding a center-running bike/pedestrian path, reconfiguring the eastbound and westbound I-580 ramp termini with a two-phase signal, and installing new traffic signals and crosswalks at the ramp termini.
As part of the environmental review, it is requested that the Interagency Consultation Partners concur that the projects are not a “Project of Air Quality Concern” (POAQC) and will not result in new violations of Federal PM2.5 and PM10 air quality standards. The NEPA document for this project is CE (23 USC 326); therefore, Caltrans and EPA concurrences are requested.
Public comments can be submitted to Phimmasone@sjcog.org through February 16, 2026.
An interagency conference call and public meeting has been scheduled for February 18, 2026, at 1pm (PT).
Contact Person:
Ty Phimmasone, Senior Regional Planner
555 E. Weber Avenue
Stockton, CA 95202