if you need to store them why don't you just have them as lookup columns in your list as opposed to disconnected controls on your form?

this post might help:

https://community.nintex.com/community/build-your-own/blog/2016/08/16/dealing-with-cascading-lookups-in-nintex-forms

Hi Cassy,

To my knowledge, using cascading lookups on the SharePoint site requires some javascript or SharePoint Designer.  We're not able to use either in our SharePoint environment. . .  

I read the post you supplied and that's exactly how we've set up the lookups within the Nintex form.

If there's other ways to accomplish having cascading lookups that can be pushed to the list and can be used to start a workflow, I'll all ears!

So on your list itself add two columns

first column type lookup called "facility" and point it to your facility list

second column type lookup called "dept" and point it to your dept list

customise your list form with Nintex form (after you've added the columns). Then access the second lookup (the one that should be filtered) and configure it to filter by the other one as I have done in my post.

i am on mobile and unable to do any screenshots but that way your facility and dept data will save back to the list too and you can use it in your workflow  

Awesome Cassy!  Adding references in my original list to the lookups was the fix.   It solved the issue of grouping my list content by one of the lookups.  And I could easily pull the information into the workflow.  Thanks!

That's fantastic news!!

can you mark the answer as correct to close out the thread please?