Opponents of the proposed Battle Mountain Gold Mine in the Okanogan Highlands of Washington state want to send Congress a message in a bottle. Because local water would be polluted by the mine, critics say, they've created the Okanogan Highlands Bottling Co. to give others a taste of what might be lost. A bonus: customers can put their complaints about the 1872 Mining Law in the empty plastic bottles and mail them to Washington, D.C. Contact the bottling company at P.O. Box 433, Tonasket, WA 98855, 509/485-3912, e-mail: mbuffalo@hotmail.com, or check out its Web site at www.purewater.org.