Is client side validation nessesary in Django?
If you have a web application that faces the public internet client side, validation is pretty much a user expectation. You might be able to ignore this if volume is low and people are motivated to use your website.
For an company intranet site, the additional development cost may weigh against client side validation. However, if you use an available client framework (e.g. jquery or django-parsley) the additional cost for client side validation is actually fairly small and likely worth the effort in intraweb applications.
ADDED
Yes, as others had already stated client-side only validation is very bad as it is the same as no validation -- you can coerce the browser to send whatever you want back to the server.
You can do also do lots of nice things client side that you cannot server side. Sometimes these are closely related to client side validation. 
E.g., limiting a comment to 500 characters. With client side code you can display a characters remaining count on screen -- with a little planning this can be integrated with the validation code.
I am writing a Django app, and am wondering if any client side validation is necessary.  Django handles all validation through forms in python on the backend.  If something validates wrong, the user is returned to the screen with all their information still there.
I can't see any reason I need to implement client side validation in Django?  Is this true?  The only reason I can think of is it would save a few hits to the server, but this seems negligible.