Ksi Sii Aks

The Ksi Sii Aks (/sɛsˈsiːæks/; formerly gazetted as the Tseax River /ˈsiːæks/) is a tributary of the Nass River in northwestern British Columbia, Canada.^[3][6] It is most notable as the namesake of Tseax Cone, a volcano within its basin that was responsible for an eruption in the 17th century that killed 2,000 Nisgaʼa people. Prior to the eruption, the Nisgaʼa name for this river was Ksi Gimwits'ax.^[3] Buried by the eruption, it eventually resurfaced. The Nisgaʼa recognized it as the same stream but renamed it Ksi Sii Aks: sii aks means "new body of water".^[3] Lower Vetter Creek, just west of Ksi Sii Aks, was also buried by lava from Tseax Cone. Both flow through Nisga'a Memorial Lava Bed Provincial Park as they near their confluences with the Nass River.

Ksi Sii Aks
Ksi Sii Aks
Mouth of Ksi Sii Aks
Location
Country	Canada
Province	British Columbia
District	Cassiar Land District
Physical characteristics
Source	Nass Ranges
• location	Hazelton Mountains
• coordinates	54°59′13″N 128°55′15″W[1]
• elevation	1,310 m (4,300 ft)[2]
Mouth	Nass River
• coordinates	55°13′20″N 129°6′24″W[3]
• elevation	29 m (95 ft)[2]
Length	45 km (28 mi)[4]
Basin size	610 km2 (240 sq mi)[5]
Discharge
• average	21 m3/s (740 cu ft/s)[5]
Basin features
Tributaries
• left	Poupard Creek, May Creek, Alder Creek, Aquila Creek, Auk Creek
• right	Tumbling Creek, Jay Creek, Crater Creek, Bubo Creek, Canard Creek, Eider Creek, Teal Creek, Fulmar Creek, McLeod Creek, Gitzyon Creek, Gingit Creek
Topo map	103I14 Oscar Peak 103I15 Kitsumkalum Lake 103P2 Lava Lake 103P3 Tseax River

As prescribed by terms of the Nisgaʼa Treaty, the Tseax River was officially renamed the Ksi Sii Aks on 11 May 2000.^[6]

Ksi Sii Aks flows about 45 km (28 mi) north to the Nass River.^[4] From its source near Sand Lake the river flows through Sand Lake,^[7] Gainor Lake,^[8] and Lava Lake.^[9] It collects many tributary streams, the largest of which are Poupard Creek,^[10] May Creek,^[11] Alder Creek,^[12] Crater Creek,^[13] Auk Creek,^[14] and Gitzyon Creek.^[15]

See also

• List of rivers of British Columbia