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Centennial Creek-CalTrans Mitigation

Construction Schedule

Groundbreaking began 8am August 22nd, 2022

Week 1: Tree trimming, heavy equipment delivery, material drop off, project staking 

Week 2: Finish tree trimming, begin grading and rock placement

Week 3-6: Grading, roughened riffle installation, erosion and sediment control

Week 7: Grading complete. Install coir logs and seed disturbed areas.

Native plant installation tentatively scheduled for November 14th, 2022 - December 8th, 2022


Phase 2 (Nickerson to Lana) anticipated July 2023. 

Request for Proposal-Centennial_phase 2.pdf


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Project News



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Project Description
Construction of the State Route 46 Corridor Improvement Project has impacted wetlands and other waters in the Union, Whitley 2A, Whitley 2B, and future Cholame section. Onsite mitigation is maximized within the Caltrans right-of-way; however, additional acreage is required by jurisdictional agencies but cannot be accommodated onsite. The remaining acreage of offsite mitigation requirements for the Union segment consists of approximately 0.474 acre of wetlands creation and enhancement, while the Whitley 2A and Whitley 2B segments and Cholame section require approximately 3.292 acres of other waters creation, enhancement, and re-establishment.

The Centennial Creek Mitigation Project intends to improve the hydrology and function of the creek by removing and/or replacing undersized culverts, removing hardscaping and debris, and engineering roughened riffles (shallow portions of the creek with large rocks placed to form natural habitat) at intervals along the system to encourage aggradation and reestablishment of a riffle/pool system.  The total area proposed for mitigation is approximately 4.14 acres, which includes 0.53 acres of wetlands creation and enhancement, as well as 3.61 acres of other waters creation, enhancement, and re-establishment.  The improvements to the infrastructure will be followed by over two acres of planting a variety of native species to create vegetation structure and increase plant diversity and habitat quality.  A plant establishment period will be for 3 years, followed by a monitoring period of 7 years, for a total of 10 years after planting to successfully meet agency success criteria. 

Caltrans established a partnership with the City of Paso Robles and the Upper Salinas-Las Tablas Resource Conservation District in 2017 to identify potential project sites to meet its mitigation requirements.  Project design, implementation, maintenance, and monitoring will be the responsibility of the Upper Salinas-Las Tablas Resource Conservation District through funding provided from Caltrans. The property will remain under the ownership of the City of Paso Robles as designated Open Space, with the mitigation site protected by a conservation easement.

Find out more information here:

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