Buena Vista Lagoon has been slowly filling up with reeds and sediment since it was dammed in the early 1970s by a weir at the mouth. Historically, the lagoon was both a saltwater and freshwater environment, depending on the influence and timing of ocean tides and upland streamflow. If nothing is done, the lagoon will eventually become a wet meadow and North County will lose an important piece of habitat for resident and migratory birds.

In 2004, CDFW led efforts to restore the lagoon; however, stakeholders failed to agree and the efforts stalled. Property owners near the lagoon’s mouth hold easement rights to the weir and also own a small portion of the lagoon. Fearing that removing the weir would drain the Lagoon and replace it with mud flats, they insisted that it remain a freshwater system, with the weir kept in place. Conservation groups, including the Buena Vista Audubon Society, advocated for the weir’s removal in order to become a saltwater environment. Removing the weir would allow the lagoon to connect to the ocean and to maintain a variety of saltwater habitats, subject to tidal influences. Currently, there are no mud flats along the lagoon’s edges. Mud flats are being lost elsewhere due to sea-level rise and thus a saltwater lagoon would provide this critical habitat for shorebirds. A saltwater lagoon would also function as a nursery for ocean fish, improve water quality,  reduce severe infestations of mosquitoes, and reduce flooding.

In July 2022, State Fish and Wildlife Department officials awarded a $1 million grant to the San Diego Association of Governments for planning the restoration of the Buena Vista Lagoon at the Oceanside-Carlsbad border. The $1 million adds to $3 million the state Wildlife Conservation Board awarded in 2021 to SANDAG for the proposed cleanup of the stagnant 220-acre lagoon. The new grant gives the agency about half the money it needs to finish the engineering and design work that must be completed before the project can be offered for construction bids.

No funding has been allocated so far for construction, which is expected to cost between $80 million and $90 million. The restoration should be finished in three to four years after the construction contract is signed. Much of the lagoon will be excavated to remove the silt and cattails that have been slowly filling the basin for decades and to open a new channel to the ocean. The weir at the outlet will be removed to allow ocean water to flow in and out, changing what has become a freshwater marsh back to a saltwater wetland.