can 'whatNWISsites' take multiple pcodes?
whatNWISsites(stateCd="OH",parameterCd=c("00665", "00060"))
URL caused an error:http://waterservices.usgs.gov/nwis/site/?format=mapper&stateCd=OH¶meterCd=0066500060
Use case: I want a list of sites that have param X and param Y