I hope you don't ask me why they call it Red Lake, because I don't know. Perhaps it is because much of the rock in the area is red? The lake itself has a turqoise color caused by being full of glacial silt. The very fine particles suspended in the water change the apparent color of it by altering the way light from the sky is reflected back up through the water. Notice beyond it is Lower Red Lake, which has a normal blue color scattered from the sky because the water is clear. And, you might notice, the east face of Split Mtn drops quite steeply down towards the lakes.