Latvian harbour of Wantspils was to replace Riga in winter time according to the Weekly Intelligence Summary No. 43 dated 29 October 192

An item reported that the harbour of Wantspils (Windau), Latvia was to be dredged immediately to a depth of 24 feet to be completed by begin december to support the increaed transit trade of Russia and to replace the harbour of Riga if that was frozen up in the coming winter.

Source

The National Archives, Kew Gardens, England CAB-24-129-57