Tuesday, November 24, 2009
Comparison of Laguna Salada, Rodeo Lagoon, and Pescadero Marsh
The "Destroy" Sharp Park folks have been claiming similarities between Laguna Salada and two nearby lagoons - Rodeo Lagoon in southern Marin, and Pescadero Marsh, south of Half Moon Bay. They've been saying that since the farthest inland parts of Rodeo and Pescadero are fresh enough to support red-legged frog habitat, that means a restored Laguna Salada would be too.
Here are topographic maps of the three areas being considered. The Laguna Salada topo map is from 1915, and would represent the lagoon if it was "restored" to its pre-golf course state. The map of Rodeo Lagoon is from 1978, and the map of Pescadero Marsh is from 1997, which were the latest I could find.
Look at how Laguna Salada runs along the length of the beach. Then look at how far inland both the Rodeo Lagoon and Pescadero Marsh extend. Even though Rodeo and Pescadero are classified as brackish, it's believable that during parts of the year, they both have relatively fresh water well inland. But does anyone familiar with the terrain at Sharp Park really believe the water at the "distant" edge of the lagoon is far enough away from the ocean to be fresh?
* The red line running down the beach on the map of Pescadero is Highway 1, just to give you an idea of how far inland the marsh runs.
* Even though they aren't permanent features, and therefore aren't shown on the map of Laguna Salada, if you look at the picture of Laguna Salada in Chris Hunter and Bill Drake's Acadia book on Pacifica, you'll see an outlet running between the Laguna and the ocean which facilitates mixing of ocean water with lagoon water.
* Also the maps are not equal scale - the Rodeo and Pescadero maps are equals scale, but the Laguna Salada map was at a much higher scale. I'm guessing if the Laguna Salada map was the same scale of the other two, Laguna Salada would look about a fourth of the size it does in the map below.