[4] The West Fork of the Foss River exits Delta Lake in two outlets which merge into one stream shortly above the top of Upper Foss River Falls.

Two waterfalls are found neighboring the lake, both at the northern outflow of the lake: 337 ft (103 m) tall Upper Foss River Falls and 251 ft (77 m) tall Lower Foss River Falls.

[1] Approximately a mile west downstream of the Delta Lake's inflow from Big Heart Lake is a third waterfall,[4] 1,262 ft (385 m) tall Big Heart Falls, while 424 ft (129 m) tall Angeline Falls is located about the same distance upstream the West Fork Foss River from Angeline Lake towards Delta Lake.

[7] A prominent delta flows into Delta Lake formed by the West Fork Foss River and other streams from Big Heart Lakes.

This King County, Washington state location article is a stub.