Yes, apparently it is exactly the result of that phenomenon. The articles I mentioned earlier in this threadarnoldo wrote:From pg 166. . .Although the Gihon Spring was the only source of water in Jerusalem, and although it regularly delivered abundant water, the Gihon was an intermittent spring. The Hebrew name of the spring is derived from the verb meaning "to gush forth." Thus the name itself seems to reflect its intermittent character. . . The geological reason for this irregularity is that the Gishon Spring is a siphonic spring created by underground water collected in a karst. When the water level reaches the top of the karst, it is siphoned off through crack in the rock. Thus, water gushes out into Hezekiah's Tunnel until the karst is emptied. At that point, the water ceases to flow until the karst fills again and the process is repeated.
Could the "stirring of the water" be the result of this geological phenomenon?
viewtopic.php?f=3&t=1319&start=20#p29745
discuss the issue in depth. Unfortunately, they may not be available outside of JSTOR's pay wall.
The articles also make the point that the healed paralytic's violation of the Torah by carrying his pallet on the sabbath presupposes a location outside the city walls. As I understand it, the walls created an "eruv," inside which various sabbath laws are relaxed. There are eruvim in many places today. So the pool near St. Anne's, being inside the then walls, is an unlikely location of the healing and subsequent controversy depicted in John 5 - even though it seems to have had five porticoes.
I'm not sure exactly how all this helps solve the problem of dating gJohn. As was suggested above, perhaps the writer conflated the two pools.