What is "sister bay"

Population (2000): 886
Housing Units (2000): 945
Land area (2000): 2.591228 sq. miles (6.711250 sq. km)
Water area (2000): 0.455192 sq. miles (1.178941 sq. km)
Total area (2000): 3.046420 sq. miles (7.890191 sq. km)
FIPS code: 74225
Located within: Wisconsin (WI), FIPS 55
Location: 45.187192 N, 87.123852 W
ZIP Codes (1990): 54234
Note: some ZIP codes may be omitted esp. for suburbs.
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