State parks officials are issuing an advisory to Iowans that most “surfacewaters” in Iowa are safe to swim in. Michael Carrier, administrator of Iowa’s Parks, is critical of a Friday DesMoines Register article which concluded some waterways — including BlackHawk and Big Creek Lakes — are unsafe for Labor Day weekend swimming.Carrier says there is insufficient data to determine the waters are unsafe.Carrier says Labor Day is the third busiest weekend in state parks.Carrier says state officials have received no reports of swimming-relatedillnesses this year.