How can I find out if there is availability this weekend and how much?

Corp of engineers has a web site that you can go to and they will tell you what's available. Watsadler doesn't have a phone number to call, you have to call website.( Here is the number. (888 893 0678) Corp of engineers. Hope this helps.

Use web recreation.gov and enter watsadler in the search bar

You can check on the Corp of engineers website.