Head Driven Culvert - San Lorenzo Lagoon Interim Management Plan Project
NOD - Notice of Determination
Present Land Use
San Lorenzo River Mouth at Monterey Bay / Floodplain & Oceanfront Recreation Districts/Natural Area & Coastal Recreation
The project is limited to the installation of a series of three 4-foot diameter standpipes (risers) that will be partially buried in the lagoon adjacent to San Lorenzo Point and connected to a 450 foot horizontal culvert buried in the beach connecting the lagoon to the ocean. Lagoon water will seep into the porous bottoms of the risers, feeding flows into the horizontal culvert. The culvert will be fitted with a gate valve to control the rate at which water is discharged from the lagoon to the Pacific Ocean. The culvert will also be capable of maintaining water surface elevation (WSE) from the 5-foot National Geodetic Vertical Datum (NGVD) to levels of up to 7 feet NGVD in 0.5 foot increments. Outflows through the culvert will be driven by the head difference between the closed lagoon (3.0 to 7.0 feet NGVD) and the ocean (typically less than 3.0 feet NGVD). All risers will be connected to the horizontal culvert at approx.. 3.0 feet NGVD. Bolted flange connections will be used to connect segments. The culvert will maintain a head difference between the lagoon (water surface at 3-7.0 feet NGVD) and riser (water surface constant at 3-feet). The lagoon WSE will be maintained at a minimum of 5 feet NGVD. Seepage flows into the riser will be driven by the head difference, so that flows into the riser will be zero when the lagoon is less than 3.1 feet NGVD and will increase to 0.5 to 1.0 cfs per riser at 5.0 feet NGVD. CDFW is executing a Lake and Streambed Alteration Agreement No. 1600-2015-0017-R3 pursuant to section 1602 of the Fish and Game code to the project Applicant, Scott Collins, City of Santa Cruz.
(1) The project will have a significant impact on the environment
(2a) An Environmental Impact Report was prepared for this project pursuant to the provisions of CEQA
(2b) A Mitigated or a Negative Declaration was prepared for this project pursuant to the provisions of CEQA
(2c) An other document type was prepared for this project pursuant to the provisions of CEQA
(3) Mitigated measures were made a condition of the approval of the project
(4) A mitigation reporting or monitoring plan was adopted for this project
(5) A Statement of Overriding Considerations was adopted for this project
(6) Findings were made pursuant to the provisions of CEQA
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