[3] The lake is part of the Waterhen River drainage basin.

Several streams feed into Mistohay Lake, including ones that drain the southern slopes of the Mostoos Hills.

Shortly after Mistohay Creek leaves Mistohay Lake, it is met by another creek that drains nearby de Balinhard Lake.

[11] A 13.2-kilometre round-trip trail branches off from the Boreal Trail from just east of Lac des Îles and heads north-east to nearby de Balinhard Lake.

[12] Fish species found in Mistohay Lake include walleye and northern pike.