0518000233 - San Lorenzo Watershed Mitigation
All dates below are specific to the schedule of the Environmental Review and Permitting processes for this project.
ENVIRONMENTAL REVIEW AND PERMITTING STATUS
COMPLETE
COMPLETION DATE OF ENVIRONMENTAL REVIEW AND PERMITTING
ENVIRONMENTAL REVIEW AND PERMITTING PROCESSES
COMPLETED
SECTOR
Surface Transportation
CATEGORY
Project Category
DOT Projects
![Caltrans Caltrans](/sites/permits.dot.gov/files/styles/project_page_icon/public/2021-04/California_91x91.png?itok=j-gh4s_R)
LEAD AGENCY
California, CalTrans
Description:
Since 1985, the San Lorenzo River and tributaries have been listed by the Central Coast Regional Water Quality Control Board as an impaired waterway due to sediment, nutrients and pathogens affecting drinking water,fisheries,and recreationalbeneficial usesundersection303(d)ofthefederal Clean Water Act. The State and Regional Water Quality Control Boards and the EPA adopted a Total Maximum Daily Load (TMDL) for sediment in the San Lorenzo River and its tributaries (CCRWQCB, 2002). The TMDL is required to include a source analysis, numeric targets, linkage analysis, TMDLs, load allocations, an implementation plan, and a monitoring plan. The sediment TMDL and the nitrate TMDL were approved by the Office of Administrative Law in 2003 . The pathogen TMDL is scheduled for consideration in 2028. Drainage facilities are an integral part of the highway system and are subject to deterioration. The design service life for drainage facilities is typically in the range of 25 to 50 years. The physical characteristics and conditions of drainage system assets / facilities are evaluated periodically to provide an assessment of structural integrity, hydraulic performance, and roadside compatibili1y. Maintenance engineering inspection teams have identified several drainage facilities that are in various stages of deterioration and in need of timely repair within the project limits. Purpose The purpose of the project is to maintain and improve the drainage systems in poor condition to reduce maintenance needs and protect State Route 17 from potential closure due culvert failure. Additionally, improvements to drainage systems would help to minimize the discharge of sediment to the San Lorenzo River watershed. Need The Drainage System Report (DSR) identified numerous damaged culverts within the designated project limits that are in poor condition due to corrosion and deformation. If deteriorated culverts are not rehabilitated or replaced, the roadway would eventually settle and be susceptible to failure due to the erosion of the soil below the pavement. The culverts within the project limits have the potential to act as source points for excess sediment discharge into the San Lorenzo River watershed. Excessive sedimentation due to anthropogenic watershed disturbances has led to a decline in 1he health of San Lorenzo Riverwatershed ecosystems and interfered with beneficial uses of the river. As a result, a regulatory order called a sedimentation/siltation Total Maximum Daily Load imposed by the Central Coast Regional Water Quality Control Board requires that Caltrans minimize sediment loading to the receiving waters of the San Lorenzo River watershed. This can be accomplished in part via the rehabilitation of deteriorated culverts.