=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Gronskar            050/151 RLR(1930) is 9.0m below BM171M
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 12-Jul-1993
Gronskar            050/151 RLR(1930) is 9.0m below BM171M
Gronskar is an historic station last data 1932