Quote Originally Posted by apitkin View Post
Well, that is partially true, but the hydraulic head depends on the water level in the Suwannee, which depends in turn on the amount of previous rain in its watershed in Georgia and the panhandle, and also the tides in the Gulf of Mexico. When the river level is high, it suppresses flow from the Milk and Sewer tunnels and visibility can get very good (even in the Sewer tunnel). That's why Manatee is such a great option when all the other caves are flooded, as the flow is down too. If you can time your dive at high tide then you'll usually see better conditions too.

Local rainfall probably does not have a beneficial effect on visibility at Manatee.

Andy'
The level of groundwater in the recharge basin also effects the head.