Turtle temperatures - did I jump the gun?

Just like I imagine most everyone else, I spent the entire weekend
outdoors getting my ponds into "spring mode". It was wonderful!
Everyone is accounted for and healthy, and it's sooooo nice to have
them back! In addition to the 4,000 gallon koi pond, I also have a
250-gallon turtle pond with adjoining land area. Getting caught up in
the excitement of the warm weather, I cleaned out the pond completely,
taking out all the leaves and dirt that I had put there last fall so
the water turtles and frogs could bury and hibernate. I also removed
the underground "heating pad" that I had kept out there all winter for
my hibernating box turtle. Now I find it's chilly today, and they say
it's going to be chilly for the next week or more. Do i need to go
throw dirt and leaves back into the turtle pond, and bury the heating
pad again???? Can these guys survive these 50 degree days and 30
degree nights for a week? I thought for SURE it was safe to
"un-winterize".
Sue