Memes of Production

If a community refuses to stop polluting, your only options are some form of enforcement, or letting it happen. Your only response here is “It wouldn’t happen often enough to consider”, which is utopian to the point of absurdity.

I've responded that it could absolutely happen, I think you're bringing up a real issue that would need to be faced, but my point of view is that it probably wouldn't happen super frequently, which is to say, I don't think Anarchism should be dismissed as a viable way to structure society due to not having specifically a centralized way to wield a big stick against non-cooperative or harmful communities.

I am not a Utopian. Anarchism won't solve all our problems, and conflict will still arise. I just think it's the best option we currently have, and will at least reduce many of the problems we face, hopefully making it easier to tackle the problems that are left and cannot be solved with Anarchism.

you have no means of conflict resolution which can stop any intransigent community from acting selfishly at the expense of other communities without going back to the question of “Enforcement”.

As @Dippy@beehaw.org elsewhere in the comments here, a regulatory body could be created, which the different communities could then join. This doesn't entirely solve the issue if the troublesome community refuses to join or adhere to those regulations, but that body could at least collectively give the troublesome community some consequences for continued pollution.

Oh, social shaming has a good record on that, does it?

It's something they could try, I didn't say it would be super effective. Against the type of populace of Johnsville, it likely wouldn't work.

And sabotage? What happens when someone gets fucking shot for sneaking around in the middle of the night ... Is the sabotage lawful by the downriver community’s decision? What’s the next step then?

If we're assuming that no other community wants to help Tableville, that Johnsville refuses to listen to the regulatory body, that the pollution is severe enough to make Tableville's way of life downstream nonviable, and they refuse to move elsewhere, then yes; Tableville's community may decide to opt for sabotage, which could escalate to armed conflict, such as guerrilla warfare if Tablesville is much smaller.

My point is in response to the idea of Tableville being so against additional work that doesn't benefit them directly, they'll avoid it even if it's obviously hurting people. If it really just comes down to not wanting to take on more work, then it follows they'd want to avoid the extra work of fighting Tableville, especially if Tableville is telling them that they are being left no other choice than violence (to be clear, I don't think Johnsville would actually weigh the potential hours needed to clean the water vs fighting in a meeting, that would be kind've absurd. I mean if they did get to that point, holy shit that place is fucked).

Considering how people tend to band closer together when they feel under attack by ‘outsiders’, even to their own material detriment? And especially within an ideology, or rather a very specific interpretation of anarchism, that rejects the notion that outsiders have the right to tell them what to do?

Would the same not also happen under a centralized government trying to force them to abide by waste water regulations? What if they saw that as an outsider force trying to impose upon them, and thus decided to militarily fight against it? This would put them in a similar situation to Slave owning states before the confederacy formed. If there were other communities who also didn't want to clean their waste water, they could join together and rebel against that centralized authority trying to clean up all the poop water.

If instead the regulating power is an overwhelming force that would result in sure destruction, only then might they simply relent without conflict. Which, I mean yeah that solves Tableville's problem, but under a centralized government we now have to hope that it does not corrupt at some point, which is what Anarchism is trying to avoid, as it assumes all centralized power structures will at some point become corrupt.

Even to-day we see men and women denying themselves necessaries to acquire mere trifles, to obtain some particular gratification, or some intellectual or material enjoyment.

I mentioned before that even struggling people acquire luxuries to make the grind bearable. I didn't say they wouldn't still want luxuries on top of having their basic need met. I agree with Kropotkin's POV.