Last November I photographed this translucent yellow gelatinous organic mass on the floor of a shallow portion of the Elbow River. I walk by this location several times a week and the mass seemed to suddenly appear. The mass was several feet high.
Several days later the mass had deflated and was lying on the floor of the river. This implies the interior of the mass was filled with a gas.
The growth was located in a section of the Elbow River that is shallow and located between the mainland and a gravel bar about about 8 to 10 meters offshore. Until the flood in June 2013, the gravel bar was an island with a beaver lodge. The flood deposited enough dirt and gravel to connect the west end of the island to the mainland. This created a shallow blind inlet at the eastern end of the island. Since the river flows from west to east, the water movement in this newly created inlet is slow. The growth was close to the sun exposed southern shore of the river. Since the river is shallow, the temperature of the water in this location is higher. Slow water movement and a higher temperature likely favoured the growth of this organic mass.
By mid-March the snow had melted on this portion of the Elbow. Over the intervening four winter months the mass totally disappeared.
I spent research time on the Internet but was not able to identify the cause of the growth. Since the Elbow River provides the water supply for Calgary, I wondered about the toxic potential for this unusual growth. I sent the above photos to a provincial water expert to request assistance to identify the organic growth. I received a reply but no answers.
I will monitor the location this year to see if the mass redevelops.