After conducting research, I was unable to find any specific information about the boat ramp named Farm to Market Road 3124 in Zavalla, Texas. It is possible that this boat ramp may be a small, local ramp that is not widely known or frequently used.

Without more information, it is impossible to determine the exact characteristics of the boat ramp, such as its width or the types of watercraft that are permitted to use it. However, given its location in Zavalla, it is likely that the boat ramp services a nearby lake or river.

Overall, it is important to note that accurate and up-to-date information about boat ramps and their characteristics can be obtained from local government agencies such as the Texas Parks and Wildlife Department or the local county government.