According to the current regulations, entities performing activities related to:
a) the carriage of passengers by passenger ships and cruise ships,
b) the carriage of goods by cargo ships,
c) the navigation of empty cargo ships,
d) towing or floating timber,
e) the use of locks or inclined planes,
are exempt, until 30 September 2020, from charges for the use of inland waterways and their sections and water facilities owned by the State Treasury and situated on inland surface waters.
Details are regulated by Article 568a of the Water Law Act introduced by the Act of 14 May 2020 amending certain acts in the field of protective measures in connection with the spread of SARS-CoV-2 virus.
The text of the Law of 14 May is available at the link:
The Polish Water Management Authority has also introduced the possibility for entrepreneurs to postpone payments for the lease of land covered by water and to spread these payments into instalments or apply for cancelling them.