The US Office of Navigation Systems informed that the US Coast Guard will stop broadcasts from its remaining 38 Differential GPS (DGPS) sites over the next three years, completing system reductions that began in 2016.
The reduction of the remaining Coast Guard DGPS broadcast sites will begin in 2018, and will end with the last broadcast of GPS corrections over medium frequency in 2020.
Other commercial and government GPS augmentation systems are available for GPS users. The observed accuracy of augmented GPS increasingly exceeds the 10-meter accuracy requirements for harbor navigation and harbor approaches.
The National Differential GPS system was significantly reduced between 2016 and 2017, when 28 of the Department of Transportation inland broadcast sites stopped, all seven US Army Corps of Engineers (USACE) broadcast sites, and 10 US Coast Guard maritime broadcast sites.
Since 2016, USCG has affirmed that the positional accuracy provided by un-augmented GPS and GPS augmented by the US Wide Area Augmentation System (WAAS) is enough to meet Coast Guard mission requirements and navigational requirements for harbor approach.