Hi Ken,
It depends a little on how the complaints are organised within the site structure, what links they have, and what traffic these pages bring in. Unless you think domain authority is a particularly big factor in the competitive space the site operates in, I wouldn't fixate on DA. Questions you do want to answer:
- Crawl the whole site, preferably using the Google Search Console and/or Google Analytics API with Screaming Frog. Do these complaints bring in (useful) traffic? Surely part of what makes the 311 service useful for community managers is that people in their community can easily comment and see the comments of others? Thinking further down the line, if the site is difficult for people in the community to find, will they use it less, and thus will community managers see less value in the service over time? Indirectly, people leaving complaints is probably a good thing for the service; do they usually do this after searching for "potholes on main street"? This is all guesswork on my part, as I haven't seen the site.
- If you do have a lot of traffic to the complaint pages, is it useful traffic? Could you afford to lose it (because that may happen if you noindex)? Remember to bear in mind the second-order effects: if nobody complains any more, the manager doesn't need a 311 service!
- Do you actually have valuable (external) links to the complaints? We can't guess at that—the only solution is to use Open Site Explorer, ahrefs, Majestic, etc...
Without knowing more, I'll just say: there probably isn't value in having an indexed page for each complaint, but there might be value in having indexed collections of complaints, optimised for neighbourhood or street. So if there are 6 complaints about potholes on main street, a first step might be for each individual complaint-page to canonical back to the page detailing all complaints about main street. And if complaints are really that brief (1 or 2 sentences), eventually I'd prefer to change the site structure altogether, so that each complaint didn't get its own page at all, but that I had one page for each neighbourhood/street/etc, with the complaints listed there and preferably summarised in some way (i.e. "8 pothole complaints", "9 traffic light complaints, etc.) That kind of view might be useful if I was a resident of the place. You would still have to deal with pagination, especially if the number of complaints is large, but that's still going to be far fewer pages than if you have one for every complaint individually.