Bridge underclearances over navigable waterways are estimated vertical distances above normal water surface levels. These levels can vary considerably from season to season and for tidal waters will vary daily. Undercleance for tidal waters is above mean high tide. Therefore, because of these variations the elevations are provided as a service to the public as a guide and the information should be verified by field measurements by the boater if the exact underclearance is critical to the boater. SHA does not accept liability for inaccurate information.