I just did a quick check and see the survey which is included with the listing. As Bobby says, it is hand drawn, and there is a note that the wetland line is scaled from the original plat and needs to be field tested before building. Hiring an Environmental Engineer to do a wetland study would be wise if you are serious about buying the property. As mentioned above, it can be worked into the language of the offer, making the sale contingent upon your approval of the results of the wetland report.
One thing I did notice in my quick check was a very different representation of wetlands between the hand drawn survey and the County wetland maps. The County Wetland overylay maps are not necessarily accurate, but they can give you good guidance to do further research. I'll attach the wetland map from the County below. The subject lot, #28 is outlined in red. Also, note that it is possible to build on wetlands when you mitigate land. depending on the type of wetlands on the property and the location of those wetlands, and the size of the home being built and the wetlands being impacted, it may still be possible to mitigate, using the some of the subject lot. Again, the wetland map shouldn't be the only resource one is using. It is simply a guide to further your research, and hiring an Environmental Engineer would be well worth the money if you are serious about purchasing. Costs should be somewhere between $300-$400 for a wetland study of that lot.
