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The Bolsa Chica Basin Inlet Is Ten Years Old!

Posted on: Aug 24, 2016 / Conservator Q3 2016-Events-News / 3 COMMENTS


Photo by: Kelly O’Reilly

Article by: Kelly M. O’Reilly, California Department of Fish & Wildlife

On August 24th, we celebrated the tenth anniversary of the opening of the Bolsa Chica Basin Inlet. This historic event marked the reintroduction of seawater into the Bolsa Chica Lowlands after more than a century of being closed off from the ocean. And with that first incoming tide came life in the form of plankton and fish. As anyone who has ever looked at a drop of seawater under a microscope knows, seawater teams with life! Phytoplankton and zooplankton form the base of the ocean’s food chain. As seawater flowed into the 367-acre Bolsa Chica Basin ten years ago, it transformed sterile dirt and rocks into living marine habitat! Planktonic animals settled out into the newly formed Basin and became barnacles, clams, shrimp, crabs, baby fish and so much more. The Basin became both a nursery for young fish to grow up in, and a cornucopia of food for migratory birds that forage in the water and mud. To those of us who remember what this area looked like more than a decade ago, it has been amazing to witness its transformation from a field of oil wells to a seawater basin that serves as a haven for marine life and birds!


A year after the Basin was opened, volunteers from the Bolsa Chica Conservancy and Amigos de Bolsa Chica assisted state and federal agencies with planting cordgrass on mud flats around the edges of the Basin; and with processing live eelgrass that was transplanted on the Basin floor by NOAA and CDFW scuba divers. Some of the transplanted chord grass survived and has gradually spread throughout the Basin. In contrast, the transplanted eelgrass took off in a big way! The 0.8 acres of eelgrass initially transplanted has expanded to well over 100 acres. Eelgrass beds provide important habitat structure for many marine invertebrates and fishes. These animals use it for feeding, depositing eggs, and to hide from predators. Indeed, eelgrass beds are so important; they were given special status under the Federal Clean Water Act of 1972.


Bolsa Chica Basin I - Eelgrass planting_Richard Herman (photographer)

Photo by: Richard Herman

In January of 2012, the California Department of Fish and Wildlife, which manages the Bolsa Chica Ecological Reserve, included the Basin within its system of Marine Protected Areas. The Bolsa Chica Basin State Marine Conservation Area (SMCA) includes the entire Basin and Inner Bolsa Bay. These are “no take” areas.


Since the completion of the 2004-2006 Bolsa Chica Wetland Restoration Project, when 923 acres of wetlands were restored, including the creation of the Bolsa Chica Basin, 181 acres of muted tidal basins and the 42-acre Pocket Marsh, there have been numerous biological surveys to assess the habitat. These surveys have demonstrated that the Basin supports 65 of the 69 marine fish species known to occur on the Bolsa Chica Ecological Reserve. The Basin also supports over 55 marine invertebrate species and provides foraging habitat for over 70 avian species. During high tides, California sea lions occasionally feed on fish inside the Basin. Green sea turtles have been seen in the Basin inlet and would certainly be attracted to the Basin’s eelgrass beds. California grunion have also spawned in the sand within the Basin inlet.


Speaking of sand, a lot of it becomes trapped within the inlet as the longshore current flows down our coastline. Because more sand comes in the Basin with each tide than flushes out, the mouth of the inlet will close if it isn’t dredged periodically. If sand were to plug the inlet and prevent oxygenated seawater from getting into the Basin, the marine life within the Basin would be in grave danger. Falling amounts of oxygen would be rapidly consumed by sea life and water temperature would increase. Such conditions would spell biological disaster, and a major die-off could occur!


Obviously we can’t let that happen. Over the past couple of years, the California State Lands Commission has attempted to secure funding to continue maintenance dredging of the Bolsa Chica Basin to ensure that this wonderful marine habitat will continue to flourish. Securing funds to maintain any wildlife area is a challenge, but the continued health of the Bolsa Chica Basin and its wildlife depends on it!

Bolsa Chica Basin III - Aerial view

  1. 3 Comments
  2. Carol Chapin
    Aug 24, 2016 at 7:05 pm

    Wow! Ten years already! Seems like only yesterday that the construction of the inlet and the causeway over it were built. I’d love to see photos of the tidal basin before the inlet was built and after. So glad to see health and vigor returning to the area that we all love so much and call home.

  3. randy perez
    Aug 25, 2016 at 12:13 pm

    Let me know how I can help

  4. Reg Adamson
    Aug 25, 2016 at 2:17 pm

    We need to concentrate on naturalizing (eliminating the oil paths and wells ) and returning this coveted area to sea and wildlife.

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