One of my favorite places to explore for over the past 30 years is over at the Los Penasquitos Lagoon. Can I take you on tour?
Ok! Let’s go!
Located between the city of Del Mar to the north and the border of San Diego to the south, the Los Penasquitos Lagoon is a 510-acre coastal salt marsh estuary.
Translated from Spanish, meaning “The Little Cliffs,” the Los Penasquitos Lagoon frames the northern part of the Torrey Pines State Natural Reserve and is designated as a Natural Preserve.
The Los Penasquitos Lagoon is a Salt Marsh?
Los Penasquitos Lagoon is one of the last remaining salt marshes left in southern California. The lagoon supports a large variety of plants and animals, including seven threatened or endangered species.
Another interesting fact is that this lagoon also serves as a refuge for migratory birds that use the Pacific Flyway.
Since joining the State Park System, there have been quite a few changes to help increase the overall tidal flow here at the Los Penasquitos Lagoon.
Let’s now have a look.
Places nearby- Torrey Pines State Beach
Activities- Hiking, bird watching
Los Penasquitos Lagoon History
Development within the lagoon in the 1880s and the 1930s have modified the lagoons hydrology process.
There are several reasons for how this eventually happened.
Sante Fe Railroad Track at the Los Penasquitos Lagoon
First off, in 1925 the Sante Fe Railroad built a single-track roadbed causeway embarkment down the center of the lagoon for its Surfline.
Can you believe that this track is still in use today on a daily basis?
The embarkment severely restricted the normal historical lagoon drainage for the first time and ultimately this changed the tidal flow.
A New Highway 101 Bridge Over the Los Penasquitos Lagoon
In the 1930s the Pacific Coast Highway, otherwise known as US Route 101 was expanded, the roadbed along the beach heightened, and a bridge built over the mouth of the lagoon.
The waterway under the bridge would continually get clogged with sand and debris due to the 72 wooden pilings. This debris, in turn, would impact the flow of water between the ocean and the lagoon.
In 2005, a new bridge was built for uninhibited water flow.
Do you notice that there are only four cement pilings? Because of this, the lagoon being closed off by sand and debris doesn’t happen anymore.
Due to the very low tide, the tidal flow out to the beach is stronger than usual.
Fun fact- My husband and I would consistently come out here to Torrey Pines State Beach back in the early 1990’s when we were dating.
One of our favorite things to do was to go at night with flashlights. We would shine the light into the mouth of lagoon looking for Gray Smoothhound sharks and other fish. Their eyes would glow green with the reflection of light.
Let’s now have a look at the mouth of the lagoon from on top of the bridge on Highway 101.
Do you see the metal pole sticking out of the water towards the left? That is a monitor that keeps track of the tidal flow that comes in and out of the lagoon.
North Beach Entrance Parking Lot at Torrey Pines State Beach
In 1983 the Los Penasquitos Lagoon Foundation was established. The primary function of this foundation, to this day, is to keep the mouth of the lagoon open, improve circulation of the lagoon as well as to restore habitat.
According to the Los Penasquitos Lagoon Foundation and the State Coastal Conservancy, the building of the fully paved North Parking Lot in 1968, considerably altered the lagoons hydrology (water circulation).
Could this lagoon ever catch a break? First, off the railroad, then clogged bridge pilings and then finally a cement parking lot. All three structures wreaked havoc on the water circulation!
Continuing from the North Parking lot and following Carmel Valley Road, there is an unofficial path in which you may view the lagoon from behind a barrier. Let’s go!
Los Penasquitos Lagoon Trails
Although almost all of the lagoon is off limits to the public, there is one trail- The Marsh Trail that is open to exploring!
To reach this trail, you must start at the South Beach entrance off of North Torrey Pines Road (HWY 101).
You will find the trailhead not that far south on the east side of the road. The trail winds around the western side of the Reserve, finally ending up in the industrial area of Sorrento Valley.
This trail is not a loop, so you must turn around and come back, so keep that in mind. If you go to the very end, the roundtrip would be about 4 miles.
There are many plants and animals to look out for, so keep your eyes open!
My Special Place-Los Penasquitos Lagoon
Well, thank you so much for joining me on a tour of the Los Penasquitos Lagoon. As you can see, it is not enormous, but it sure has character.
Check back later as I plan on taking a hike on the Marsh Trail shortly!
As I have previously stated, this lagoon has always held a special place in our hearts. I feel incredibly fortunate to have seen so many improvements and witness the transformation of this lagoon over the last 30 years.
The new bridge has a lot to do with this, so thanks to the new bridge! Thank you for allowing more water into the lagoon and improving the circulation.
And a special thanks goes to the Los Penasquitos Lagoon Foundation for all the hard work and dedication they all put into preserving as well as researching this environment.
I hope that one day you may witness the Los Penasquitos Lagoon in person. There are so many beautiful places to discover in San Diego, especially on the coastline!
Please leave any comments or questions that you may have down below.
Until next time!
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I have always had a deep-seated passion for the Ocean Environment which ultimately led me to receive a degree in Marine Biology. Living in the San Diego area for over 30 years, I have extensively explored the 70 miles of San Diego’s coastline, and I am here to share! Please use my website to your advantage and have a look around at all the wonders that the beaches of San Diego can offer you!