If you didn’t understand the inherent problems with mixed use development on Portland’s waterfront, the recent release of e-mails between city officials and the Pierce Atwood law firm should clear it up.

The documents, revealed in response to a Freedom of Access request by The Portland Press Herald, show a law firm that was threatening to pull out of a multimillion-dollar redevelopment deal by the water because of the presence of refrigerated trailers filled with lobster bait next door.

They also show the city ready to keep the law firm happy and the development on track by moving the bait business.

The fact that both businesses appear to be happy with the outcome (the bait business will be moved to another location) does not mean that this isn’t a serious conflict and that it won’t happen again.

The City Council’s Community Development Committee is preparing recommendations on changes to waterfront zoning that could upset the balance Portland has struck.

Water-dependent businesses make awkward neighbors. They are busy at strange hours, they make noise and in some cases, they smell bad.

But they are businesses that can only operate in one place –  by the water, and they not only give Portland its character, but they provide jobs to people who need them.

A group of central waterfront property owners is asking for the zoning to be relaxed, giving them more flexibility to bring non-water-dependent businesses into their buildings, generating enough income, they say, to pay for investments in upgrading the piers and infrastructure needed to keep the fishermen in business.

That may be so, but as the Pierce Atwood example shows, conflicts are inevitable. When they occur, the city may not be able to find mutually beneficial solutions. If the working waterfront is going to survive, uses like the bait trailers will sometimes have to win out over the multimillion-dollar office projects.

Somehow that principle should be incorporated into any change to the zoning ordinance that changes the balance of the types of businesses on Portland’s waterfront. If not, the Pierce Atwood experience shows, Portland may not be able to hold on to its working waterfront much longer.