The stuff used to treat "treated lumber" has changed a great deal over the years to make them less hazardous. Arsenic hasn't been used for over 15 years. Wikipedia gives a good rundown of past and current processes; it looks like mostly copper compounds are used today.

Lots of copper compounds used in pond treatment, but I don't know if the wood treatment coppers are a problem in ponds. Gotta be better than Arsenic, though.

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
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