topo map reference icon ??

Here is a section from a 1957 topo map of a location I want to get permission to search. Does anyone know what these ovals and hashmarks represent on a topo map????? I tried looking up the symbols for topo maps and didn't see these on the icons. Any map specialsists on here????

I have never seen symbols like that on any maps I've looked at :dontknow: I hope some can shed some light Robbie .

Because they are in blue, it means water. The lines being dotted means temporary of intermittent. By the looks of the map and the shape, I would think those are ditches or mad made runoff areas that may stay wet for long periods.

http://pubs.usgs.gov/gip/TopographicMapSymbols/topomapsymbols.pdf

My guess is wet areas during rainy time of the year.