You can help protect the health of our precious lagoon! Artificial breaching may be the single most damaging factor to the health of the lagoon environment.
The lagoon and estuary are located under the Hwy 1 bridge at San Gregorio State Beach. In a natural, healthy state, the lagoon is a critical interface between ocean saltwater and the fresh waters of San Gregorio Creek. Fresh and salt water mingle throughout the season in this area, providing species like Coho and Steelhead Salmon, as well as the Tidewater Goby, a place for successful spawning and rearing.
The sandbar is the seasonal barrier between the ocean waves and lagoon waters. When the sandbar is artificially breached, whether by accident or on purpose, an entire season of spawning can be comprised in minutes. The public can be a great help in preventing artificial breaching by being aware of the dire consequences to the fish and wildlife of unnatural opening of the sandbar to the ocean.
The lagoon is opened naturally to the sea when wave action during the winter months break down the sandbar. At the same time, there is pressure from the creek side as winter rains move great volumes of water downstream into the lagoon. Once the sandbar is sufficiently weakened, water built up on the lagoon side pushes through and drains into the ocean (see photos).
We were fortunate this year to have numerous people watching the lagoon as it swelled to unusual proportions. Some were present with a camera when the breach occurred in late October capturing the event in photos. Within approximately 1/2 hour, the lagoon went from a small bay to a gently meandering stream.
As part of San Gregorio Environmental Resource Center’s (SGERC’s) current grant from the Environmental Protection Agency, daily and weekly monitoring of the San Gregorio lagoon began in October 2010. Monitors began noting both the condition of the sandbar (open, closed, about to breach etc.) as well as water quality parameters at three locations in the lagoon.
The monitors check water quality at just below the surface and just above the bottom at three sites in the lagoon. They also note the level at which the water column changes from fresh to salt water (stratification layer). Using a kayak, a handheld YSI meter, a camera and data sheet, these monitors spend several hours a week collecting data in the lagoon. This monitoring will continue throughout the year, at which point our project partners will compile and analyze the data. SGERC will continue to share data throughout the year with our technical advisors and members of the public through our Watershed Working Group.
Our goal is to understand the temperatures and water quality conditions that exist in the lagoon throughout the season, and compare them to the needs of various species. This will enable us to determine if something can be done to improve their spawning and survival. Please help us protect this important research as well as the health of the lagoon and stream system by refraining from damaging the sandbar.
Feel free to contact SGERC with any questions about the lagoon or our ongoing work in the San Gregorio Watershed. Call (650) 726-2499 or email Neil at firstname.lastname@example.org.
Oct. 2010 Lagoon breach photos courtesy David & Sandra Zink
(Also published in The La Honda Voice, February 2011.)
Protecting the San Gregorio Watershed.