Lake Merritt creature, monster or mermaid?

Lake Merritt is a wildlife refuge dating from 1870 I believe. It is home to  fish, crabs, sponges, copepods, tubeworms, water and land birds, and lots of other wildlife. You can find out more here :http://www.lakemerrittinstitute.org/index.htm

But is it also home to a monster? The stories surfaced in  2007 of a creature in the shallow lake(about 11feet deep, 3.5 metres) and went on for a couple of years see here:
http://oaklandnorth.net/2011/06/22/is-there-a-monster-in-lake-merritt-scientist-says-yes/

A hoax was said by most but then someone uncovered stories from 1940s and 1950s in the local newspaper.

“Sooner or later every loch must have its monster. Today we give you the Lake Merritt MONSTER! The legend, which some go so far as to disbelieve, dates back to that far-off time when turgid streams snaked their way down from the hills to form San Antonio creek. On a day of untold lightnings and unseemly thunderings...a vast, slimy amphibious creature slithered along one of these water courses, waded along the creek till he came to the estuary, and hollowed out with a fillip of his tail the basin that later became Lake Merritt.”– J. Burroughs, Oakland Tribune - June 21, 1946

There are various recent reports from people who say  they have seen the creature and they tell that  that sightings begin with a slow roiling bubble on the surface of the lake. Then a dragon’s head attached to an eel-like body with undulating humps appears. The sighting usually lasts a few seconds then the creature  submerges with more bubbles.

The Lake Chalet bartender, Laurance Alvarado claims to have seen the beast more than once. “I remember the first time I saw it. It went in and out of the water, then disappeared. It was literally right there, I could’ve thrown a stone at it.” Alvarado described the creature  as  8/9 feet long ( just less than 2  metres). He also says, “It wouldn’t surprise me at this lake, some mutant thing.”
However there is another story about the lake , about the mermaid that was said to live there in the 1800s. She was a beautiful woman , half fish and sightings of her form persisted for many years but petered out. In the 1880’s Oakland City’s untreated sewage was dumped in the lake and many said that had killed the mermaid.
Could the Lake Merritt Mermaid and the Lake  Merritt Monster be the same thing that was seen. Possibilities include  a large fish, a salamander or something like a manatee or seal that was stranded or dumped there? It is interesting that since the lake has been cleaned the stories of a creature in the lake also re –emerges. So what do you think monster, mermaid or hoax?