The cache is not at the posted coordinates. Look at the three plaques and find out which two familes had cleared had lemon ranches in this areas. As listed on the plaque, input the two family names into Certitude to get the correct coordinates for the cache.
You can validate your puzzle solution with
certitude.
Please be stealthy as this park can sometimes be quite busy. If there are people relatively close, then come back at another time. The smiley face stamp stays with the container. It is not swag.