The dogs, thought to be Staffordshire bull terriers, were discovered in Newent Lake on Saturday, August 26 at 3.40pm.
They were found by a concerned member of the public who contacted the RSPCA.
RSPCA inspector Jon Ratcliffe said: “This must have been a shocking discovery.
“I want to thank the kind-hearted caller who notified us and removed the bodies until we were able to collect them and have them examined by the vet.
“The poor puppies’ bodies were found in the water, with one placed inside a white sock. They still had their umbilical cords attached.
“We think it is likely the pups were dumped at this location in the hours of days leading up to their discovery.
“I am eager to speak to anyone who has any information as to who these pups may have belonged to, or if they saw anyone acting suspiciously at the location.
“Anyone with information can contact me in complete confidence through our inspector’s appeal line number on 0300 123 8018.”