I concur I wouldn't worry too much about the salt. Salt is measured typically in aquaculture in parts per thousand which is a much higher salt content than parts per million. Some salt can, in fact, be beneficial to fish and many freshwater fish can tolerate brackish water which is higher than your 410 ppms.

Some aquaculturists are actually raising certain freshwater fish species with water drawn from saltwater wells.

However is there contamination from anything else as in oil remanants? Oil is very bad in itself.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.