My husband and I visited the Chattanooga Zoo on Sunday, June 2, 2013. We had to dodge rain showers, but there were plenty of indoor exhibits and overhangs to keep us dry. :-) On the good side, we had the entire zoo to ourselves for pretty much the whole trip. :-D
I found the zoo to be wheelchair-friendly, with a few things worth mentioning.
Some of the threshholds were a little difficult to cross with my wheelchair. A couple of times I found it easier just to stand up, step over the threshhold myself, and then pull my wheelchair on across. It wasn't much of a problem, but it might be for someone who is unable to stand or walk at all.
The boardwalk with the built-in train tracks is VERY slippery when wet, especially the area where it turns into an arched bridge. Wheelchair or not, use caution!
The red panda exhibit is questionable as far as wheelchair accessibility. There was a sign saying there was an elevator, but we couldn't find the location, and there didn't seem to be any attendants nearby. I finally walked up the 12 or so concrete steps myself, and entered the exhibit. My husband carried my wheelchair to the top so I could sit down once I was there. Afterwards, I walked down the second set of steps (wood), which were a little slippery from the rain. It worked out okay, but I wouldn't have gotten to see the red pandas, turtles, and some birds if I hadn't been able to go up and down the steps on my own.
The cougar exhibit is viewed from a railroad car, and you go up a wood ramp to get into it. However, the door leading out of the exhibit is very narrow, and there are only narrow steps at the end. A person in a wheelchair has to go back out the way they came in (down the ramp).
The gift shop has grass(?) mats at the doors, which are somewhat difficult to roll over, but they're manageable.
The petting zoo has a gravel surface, and is very difficult to access via a wheelchair when the ground is wet. I kept sinking in the gravels, making it impossible to roll. It might be better on a day when the ground is dry. Also, the camel-riding area (closed when we were there due to the rain) appeared to be only accessible via 4-5 steps that you climb to get onto the camel, so I'm not sure if that would be do-able for a wheelchair-bound person.
The restrooms do have a wheelchair-accessible stall. When we visited, the restrooms needed a bit of TLC, and I just used a regular stall due to the fact that the wheelchair stall had toilet paper hanging out of the toilet (eeeww!). But that's not surprising for a busy restroom, I suppose.
Other than those things, the zoo was very wheelchair-friendly, with the paths being either paved, cobblestones, or boardwalks. Here are some photos I snapped along the way:
Cobblestone area near the entrance/exit
The cobblestones change over to a regular sidewalk
On the sidewalk
Path to the gorilla exhibit
Upstairs at the red panda exhibit
Upstairs at the red panda exhibit
Upstairs at the red panda exhibit
Petting zoo with the gravel surface
Petting zoo with the gravel surface
Snow leopard
Servel cat