Most days I drive past the Agua Hedionda Lagoon and the Encina Power Station, with its 400-foot smokestack, on my way to and from work. Doing research about something else, I learned that the power plant, which is owned by NRG Energy (say the company name out loud to see how clever they are), was commissioned in 1954.
The lagoon is next to the ocean, but wasn’t always open to it. When they built the power plant, they opened the lagoon to the ocean so that the tidal flow could cool the plant’s gas-fired boilers. And in 1954, to make the most of that tidal flow, they dredged sand from the bottom of the lagoon and moved it over to the beach.
Here’s the break created to let the ocean’s tidal flow into the lagoon. Apparently the jetties keep the entrance from migrating and keeps it flowing under the bridge. Photo by USGS via Wikimedia Commons
I had been here a couple of years when I first noticed a sandbar in the middle of the lagoon during low tide. I assumed I was not terribly observant and had never noticed it before. But the way it was explained to me by a long-time resident of the area, the tide going into the lagoon is strong and carries in lots of sand. The tide is not so strong going back out to sea, leaving much of the sand in the lagoon. (If I received incorrect information, please feel free to correct me.)
After a few years the sand builds up, impeding the flow of the water, and NRG Energy brings someone in to dredge the sand out again. I got to watch this process over the winter of 2014-2015. A big boat (that’s the technical term) sits over the top of the sandbar and vacuums up the sand, sending it through huge tubes that go under the bridge and deposits all the sand and organic matter onto the beach on the other side of Highway 101.
Agua Hedionda Lagoon from the north end, with the Encina Power Station and its smokestack in the background. The sand builds up right in the center where the water looks ripply. The bridge is just out of the photo on the bottom right. Highway 101 separates the lagoon and the beach. Photo by Bovlb via Wikimedia Commons
When the sand pours onto the beach, it is almost black, but eventually dries in the sun to it’s normal sandy color. When it’s freshly poured and full of all sorts of sea creatures, the seagulls and pelicans and other birds that hang out at the beach are all over it like an all-you-can-eat buffet. Since they move about 500,000 cubic yards of sand, that’s a lot of food.
I noticed yesterday at low tide that the sandbar is back. Kids were out there fishing and playing. Looks like it’s about time to dredge again.
Here in Carlsbad, we just move our sand across the road, but there is actually a global sand trade. Sand is used in everything from glass to concrete to computer chips, so this non-renewal resource is in great demand. Desert sand doesn’t work in concrete to make buildings or roads because the grains are round and don’t stick together. So the quest for beach sand is not only affecting our environment as the oceans and rivers are dredged, but also creating criminal enterprises as beach sand is now a hot commodity. Maybe don’t wait to take your beach vacation.