It's not unprecedented, and there's no current threat to water supplies, but officials are prepared to start building an underwater barrier to block the denser saltwater from moving further upstream, Corps spokesman Ricky Boyett said Friday.

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Admiral Allen announced yesterday, for example, that, after a bunch of back-and-forth between state and federal experts, he is prepared to authorize moving forward with a portion of the idea for a barrier island that may stop some of the oil from coming ashore.

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