33 CFR § 117.633 - Grand River.
(a) Public vessels of the United States, state or local vessels used for public safety, commercial vessels, and vessels in distress shall be passed through the draw of each bridge as soon as possible.
(b) The draw of the CSX Transportation Corp. railroad bridge, mile 2.8 at Grand Haven, shall open on signal; except that, from December 15 through March 15, the draw shall open on signal if at least 12 hours notice is given.
(c) The draw of the U.S. Route 31 bridge, mile 2.9 at Grand Haven, shall open on signal for pleasure craft-
(1) From March 16 through December 14, from 6:30 a.m. to 8:30 p.m., seven days a week, once an hour, on the half-hour; except the draw need not open for pleasure craft at 7:30 a.m., 12:30 p.m., and 5:30 p.m. on Monday, Tuesday, Thursday, and Friday, and at 7:30 a.m., 12:30 p.m., and 4:30 p.m. on Wednesday.
(2) From December 15 through March 15, if at least 12 hours notice is given.