The surface of the Piponisiw River is usually frozen from mid-November to the end of April, however, safe ice circulation is generally from early December to late March.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request. ### Instruction: List the MITRE techniques contained in the text. ### Input: The surface of the Piponisiw River is usually frozen from mid-November to the end of April, however, safe ice circulation is generally from early December to late March. ### Response: .