Dredging

2022-23 Dredge Operations

FEDERAL ENTRANCE CHANNEL

The Port District recently secured a new 10-year dredge permit from the U.S. Army Corps of Engineers, which will allow dredging operations in the federal entrance channel and inner-harbor areas to continue seasonally through April 30, 2032.

In preparation for the upcoming season, the dredge crew will move Twin Lakes to the entrance channel on Monday, November 7, 2022. Dredging of the harbor entrance is scheduled to begin during the week of November 14, 2022, after all equipment has been mobilized. The typical dredge schedule will be Monday – Thursday, with as-needed maintenance performed on Fridays.

Weekly soundings will resume and be posted to the harbor’s website. Prior to transiting the entrance, please check tide and weather conditions, review the entrance sounding, and know what your vessel draws.

During dredging operations, pass Twin Lakes on the east side (Crow’s Nest side) of the channel unless otherwise marked. Stay at least 50’ from the dredge and contact the dredge crew on VHF channel 8 for passing instructions. If your vessel contacts any dredge equipment or pipeline, please contact Harbor Patrol IMMEDIATELY on VHF channel 9.

NORTH HARBOR DREDGING

Dredging of the north harbor is anticipated to begin on November 28, 2022, using the Port District’s 8” dredge Squirt. Dredging of fine-grained material is permitted through February 28, 2023.

To view the areas proposed for dredging and the anticipated pipeline configuration in the north harbor please click here.

The Science Behind Dredging

WHY WE DREDGE
Dredging of the harbor is required because of the constant easterly movement of sand along our coast and thus, across our harbor entrance. Such movement is generated by the ongoing forces of waves and currents. The amount of material moved and deposited is directly proportional to the severity of current and wave conditions. This constant movement of masses of sand is termed littoral drift.

Sand indicated by orange dotted areas, is carried down the San Lorenzo River and thence moved down-coast by wave and tidal action called littoral drift. Constantly moving, the sand mass builds up against the west jetty and flows around it, shoaling the Santa Cruz Harbor entrance channel. Impeding sand is then dredged from the entrance channel and deposited in the inter-tidal zone where the existing littoral drift carries it down-coast, nourishing those beaches east of the Santa Cruz Harbor entrance.

THE DANGER OF SHOALING
Because of sand incursion at the mouth of the harbor, it is essential that an annual dredging effort be maintained to assure sufficient depth at the harbor entrance to permit the safe passage of vessels transiting the entrance. Shoaling conditions caused by littoral sand drift produce dangerous and unpredictable breaking wave formations at the harbor’s entrance. These breaking waves are extremely hazardous to incoming, and outgoing vessels and pose a particular danger to individuals walking on either of the jetties.

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