Casadepaga River (also Koshotok and Koksuktapaga) (Inupiaq: Qaqsruqtaq) is a waterway in the U.S. state of Alaska, near Nome.

The drainage area is large and the stream is navigable for small boats and canoes for a distance of about 15 miles (24 km).

The bed rock of the whole basin consists of the limestones and schists of the Nome group, including many veins and stringers of quartz, some of which are known to be auriferous (gold-bearing).

The river occupies a broad and deeply gravel-filled valley, in the floor of which the stream bed is trenched to a depth of 30–150 feet (9.1–45.7 m), leaving well-marked gravel terraces and benches through nearly the whole length.

[3] Dawson Gulch joins the river nearly opposite Big Four Creek, which is named after its first four prospectors.

On the mica-schist bed rock, which was reached by test pit, flue gold is found associated with garnet.

The most important development in the Casadepaga basin during the gold mining years was the extension of the Council City and Solomon River Railroad to the mouth of Penelope Creek.

[3] In the lower course of the river, near Bonanza Creek, mining camps were established to work low-bench gravels of the Casadepaga.