Pentwater Harbor, Michigan is located on the east shore of Lake Michigan, 146 miles northeasterly from Chicago, Illinois and 14 miles southerly from Ludington, Michigan. The project was authorized by the Rivers and Harbors Acts of 2 March 1867, 3 March 1873, 5 July 1884, 13 July 1892 and 2 March 1907. The project provides for widening the old entrance channel to 150 feet between parallel piers and revetments, the channel to extend from Lake Michigan to Pentwater Lake, with a depth of 16 feet. The piers and revetments are built of stone-filled timber cribs and piling and are provided with concrete superstructure. The north pier and revetment was completed in 1885 for a length of 2,226 feet. The south pier and revetment was completed in1889 for a length of 1,847 feet. The present length of the north pier and revetment is 2,022 feet; 204 feet of deteriorated pier was removed in 1931. In 1960, the north pier was extended 60 feet by construction of a rubblemound structure. The portion of the project authorized by the R&H Act of 13 July 1892 was deauthorized in Nov 1977. The channel is currently maintained at 12 feet deep. The harbor services primarily recreational navigation interests.