The natural resources of the Nipomo Dunes and Wetlands, California Department of Fish and Game, 1976

The dunes are not the dunes, they are a wonderful wildlife habitat and there is sand in between a myriad of hollows, lakes, and waterways with numerous habitat. The wildlife born in these riparian areas, and who make homes in the vegetation, cross the open dunes that separate all of these areas the coastal dunes, beach, and wetlands are one ecosystem.

https://en.wikipedia.org/wiki/Guadalupe-Nipomo_Dunes

On Wikipedia, it says this is the largest remaining dunes ecosystem south of San Francisco. They were designated a U.S. National Natural Landmark in 1974. Of course the article rightly says that in these dunes is Oso Flaco Lake, a rare large dunes freshwater lake.

It mentions the fact that in the 18 mile dune complex situated within San Luis Bay, there are many threatened and endangered species.

I read somewhere, there are 26 threatened or endangered species under U.S. or California law!

This CCP has the best information about the dunes:
https://www.fws.gov/refuge/Guadalupe-Nipomo_Dunes/

Many more acres could be added to the Guadalupe-Nipomo Dunes Federal Wildlife Refuge including the Oso Flaco Lake natural area. In 2000 a total of about 8000+ acres were approved, but only a fraction is included currently in the Refuge.