The London 2012 double sculls winner, Cohen had retired from competitive rowing in 2013 due to an irregular heartbeat.
Watts (7m 22.77s) came second to Cohen (7m 15.98s) in the single sculls final, while Watts and Pawson chased the Cohen brother team to the line in the double sculls.
In the men's senior coxless quad sculls, Watts and Pawson teamed with Nathan Luff and James Sandston to claim bronze, behind the Canterbury team and the winning Invercargill crew which included the Cohens.
Luff would also get a silver in the men's club single sculls, finishing in 7m 23.01s behind Marlborough's Tristan Gregory-Hunt (7m 21.13).
The men's club coxed four of Sandston, Luff, Guy Thomson, Ben Tijsen-Cox and cox Niamh Mullany finished second in 6m 38.41s, behind the Avon RC (6m 35.31).