hi. thanks for the intention to contribute. in order to maximise your impact, please check this osmose report:

https://osmose.openstreetmap.fr/en/map/#loc=12/8.6606/-79.82993&level=1%2C2&item=1220

rivers should flow either to the coastline or into an other river. in OSM lakes, lagoons, and tidal areas (on the land-side of the coastline) are crossed by waterways, to indicate how water from tributary streams flows across the lake, into the outflow river.