Yes, there are concrete trails that start near the visitor center and lead you through the preserve, the concrete paths are seperated by the road but all you have to do is cross the street(there is a crosswalk) and follow the rest of the trail. You will end back at the parking lot. There are no official guides but there is usually a docent in the visitor center who can answer questions.
I see a kayak group with REI from time to time. Usually the evening. You should check their website.
You can obtain a map from the office at the preserve but as far as I know there are no guides
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