The article left off part of part of what the court said, which was (emphasis added):

> Rather, the remedy for Plaintiffs’ injuries lies in pursuing tort claims, electing representatives who will better manage the public-water system, and petitioning their representatives for other remedies.

Suing the government is indeed one of the things the court said they could do. They just can't sue alleging a violation of the particular federal statute they used in this suit.