Keep an eye on this link for the Choctawhatchee river level at Caryville. Anything 6 feet and over is usually considered blown out (not diveable) from what I've been told. Obviously the further under 6 feet you get, the better the viz typically is.
National Weather Service Advanced Hydrologic Prediction Service
Also, check this link for the park itself.
Morrison Springs | Walton County, FL - Home Page
Morrison has a reputation for getting periodic health advisories for high bacteria counts which creates a safety issue for people being in the water without risking getting sick. The Walton County Health Department routinely samples the water quality and any abnormal counts will warrant a shut down which gets posted on the park's website. If an advisory is issued, keep checking the website as the Health Department samples the water every few days. The spring area typically has issues after the river level has been up for quite a while after heavy rains since there's a lot of septic systems and farms upstream and the runoff is usually the cause, not the spring itself.