Site 11 - Anniversary Island - Mainstem

This large midstream island was connected to river-right (north bank) at low flows. The side channels included flow from an unnamed tributary, and a small cascade; both were highly tannic.

Physical Site Description- August 19; 8:40 AM
Near Killack
Partly Cloudy; cool ~ 40 F

General Description of site area:
Kobuk bends around gravel bar that is either a point bar or island, depending on flows; currently a point bar. Gravel lines the edges and two higher water overflow gravel channels cut through a large Willow patch in the middle.

Two tributaries enter from Spruce forest behind gravel bar on river right; both very red/tea-colored with tannins. Upstream tributary enters at a very acute angle (same direction of flow as Kobuk) and enters the island in the middle of its furthest back overflow channel. The overflow channel that this tributary flows into is being plugged with courser grained sediment at the top (upstream). The downstream tributary enters in the form of a small waterfall, over a bedrock ledge, creating a large but shallow pool that drains down into the main river channel. At the downstream end of the gravel bar, bedrock dominates on river right.

More detailed description of a small creek/spring on the north side of the field site:
An un-named creek/spring flows south from the hills to the north of the main channel of the Kobuk. The creek cascades over a bedrock ledge into an old meander bend which now serves as an overflow channel. The creek water is high in tannins.

The bedrock is composed of meta-sedimentary rock. Bedrock outcrops (10x15 m) on the west side of the map. Substrate size ranges between cobble and sand and in most areas is mixed with higher percent of sand near vegetation lines and in the channel. The vegetation is immature Willows, grasses, and shrubbery on the south bank of the old meander bend. The vegetation on the northern side consists of Willow, grasses, and shrubbery near the channel and transitional to Birch and Spruce.

Backwater and side creek:

Location