At one point there was not a mesh barrier on top or glass on the side of this exhibit...it was completely open. Even that ladder was not in existence but I'm guessing that the zoo had issues with foreign objects ending up in the pool. Check out this 2003 photo: http://www.zoochat.com/557/cleveland-zoo-2003-california-sea-lion-136787/ When I visited the zoo in 2010 there was a large rock wall that split the pool up into two sections, as seen in this photo: http://www.zoochat.com/557/northern-trek-harbour-seal-california-sea-174210/
Wow, it's like a human swimming pool- reminds me of the disaster of a sea lion exhibit found in Houston. Hopefully this, the bears and everything in the Primate Cat Complex are high up on the zoo's improvement list.
Yeah, this exhibit is not one of the greatest and I believe they should make improvements to it, but the zoo has improved over the years with African Elephant Crossing and now Tiger Passage. As a lifelong Clevelander, I look forward to seeing "my" zoo expand.