Annual Inlet Excavation


Reconnecting San Elijo Lagoon with the Pacific Ocean 

Clearing the Inlet after High Tides and Rain Occurred December 27-28, 2018 (see blog post).

The 2019 Inlet Clearing will be posted when known.


With the estuary overcrossed by Coast Highway 101 and the railroad, a buildup of sand occurs. These sediments are transported by high incoming tides, surf and storm surges. When the inlet becomes blocked, Conservancy teams monitor the water quality and determine the appropriate timing of an inlet excavation in relation to optimal tidal flows.

In 2001, a long-term financial endowment was established for the Conservancy to actively fund maintenance of tidal flushing. Efforts to keep the lagoon open to tidal circulation have shown that significant ecological benefits result from increased tidal flushing, as evidenced by:


When early settlers arrived, only beach and dunes separated the lagoon from the ocean. The inlet was open most of the year, sometimes closing during the late summer, but opening again with the combined force of winter rains and surf. The inlet migrated between north and south according to the prevailing forces of the season.


It has been decades since San Elijo Lagoon was naturally connected to the Pacific Ocean. Coastal development occurred at a rapid pace after the 1880s. The first bridge and berm crossing the lagoon was constructed by the railroad in 1881, followed by Pacific Coast Highway in 1891 and, in 1965, Interstate 5, which divided the wetland in half.

This partitioning of the lagoon created altered flows for both freshwater and saltwater, leading to accelerated sediment deposition, dramatically-reduced water quality, and a reduction in native estuarine habitats due to increased runoff from development upstream. During the winter storm cycles the inlet often becomes blocked by an accumulation of sand in the tidal channel. As temperatures rise in the spring, the demand for oxygen increases. Withhout the circulation provided by the ebb and flow of the tides, the entire lagoon can become stagnant. The lagoon inlet, rarely, if ever, opens naturally.

Inlet Photomonitoring Slideshow






View Slideshow
See daily photomonitoring, August 2012 - September 2013 (inlet excavation occured June 2013) of San Elijo Lagoon's only channel to the Pacific Ocean. The inlet is restricted by a railroad and highways. Watch the slow accumulation of sand and cobble that becomes trapped in this passage, thereby restricting water flow.

Tim Stillinger, Scientific Program Director
San Elijo Lagoon Conservancy
Email: tim [at] sanelijo [dot] org (subject: Lagoon%20Inlet%20Opening)