Since the late-1800s, NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS) and its predecessors have been collecting, analyzing and distributing observations and predictions of tidal currents in coastal areas (including some rivers, bays and estuaries), and observations in limited locations for river flow on the Great Lakes. Knowledge of the timing and strength of currents is extremely important for safe navigation in coastal waters. Tidal currents are often the strongest current experienced by vessels operating nearshore and for considerable distances inside bays and river estuaries. CO-OPS maintains both short-term (one-time or multi-year tidal current surveys) and ongoing (continuous real-time) measurements to ensure safe, efficient and environmentally sound maritime commerce, and to support environmental needs such as HazMat response. Data from short-term (non real-time) tidal current surveys are updated about every 25 years, in support of NOAA’s National Current Observation Program (NCOP). There are over 60 real-time tidal current stations in place as part of our Physical Oceanographic Real-Time System, or PORTS (Copyright) Program. Standardized procedures exist for analyzing ocean current data to separate the tidal and non-tidal parameters. Tidal parameters are used to generate predictions. At locations where currents are dominated by non-tidal factors, real-time measurements offer more accurate information. Standard tidal data are reported in 6-minute intervals; other data have varying intervals. Data are quality controlled. Note: tidal current predictions are calculated on the fly and are not stored, nor considered as data.