Giant garter snake
The giant garter snake (Thamnophis gigas) is the largest species of garter snake. Relatively rare, it is a semi-aquatic snake with a limited distribution in the wetlands of central California.
From Wikipedia
The giant garter snake (Thamnophis gigas) is the largest species of garter snake. Relatively rare, it is a semi-aquatic snake with a limited distribution in the wetlands of central California.