The case is Freemanville Water System, Inc. v. Poarch Band of Creek Indians (opinion). Our post on the district court case is here. An excerpt:
After a hard look at the statute the only thing that is unmistakably clear to us is that the statutory language does not make it unmistakably clear that Congress intended to abrogate tribal sovereign immunity from lawsuits claiming a violation of the anti-curtailment provision [of the Consolidated Farm and Rural Development Act]. See Kimel, 528 U.S. at 73, 120 S. Ct. at 640.
And here are the appellate briefs:
Turtle Talk 