Coulee

[…] Mauvaise Coulee enters Devils Lake from the north, but it cannot be said to drain the lakes with which it is connected. It is itself a long-drawn-out slough or pool which is broader at those places where it spreads out into lakes. […] the head streams or coulees of the Park, the Forest and the Turtle, have all cut deep channels down through the drift into the underlying shales. This is because of the fall from the top of the high plateau down to the low prairie. […] all the larger lakes upon this plateau have already been tapped by the head coulees of the streams named.

Source: wiktionary

The small streams and coulees which flow into the Mississippi River in the area are firmly entrenched by the natural topography, and little lateral migration is possible.

Source: wiktionary

We were in a coulee, which is like a slough but deeper and with slushier muds at the bottom.

Source: wiktionary

The edge of a coulee, or stream of solidified lava, though ordinarily a very low escarpment, is exceptionally of such size as to deserve attention in the present connection.

Source: wiktionary