2112 (Cable Creek) Watershed

• The 2112 watershed is one of the medium watersheds on the island, some 467.9 hectares (1,156.2 acres)* in an area of moderate to high relief and significant terrain variability on the east slope of Mount Tuam as well as a significant part of Hope Hill and the basin between the two peaks.

• Geologically the watershed area comprises a complex mix of metasediment and metamorphic rocks with local surficial sedimentary veneers. Surface flow patterns, groundwater baseflow and subsurface "aquifer", flow variability are likely to be partly a result of fault and fracture networks within discrete geo-mechanical units.

• The watershed receives something like 4,445,050,000 litres (1,174,260,000 gallons)* of rainfall (or surface water) per annum (cf rainfall calculations), and is similar in size to the Weston Creek (central Island) and Bullock Creek (north Island) watersheds.
  These volumes give no consideration of surface/terrain conditions, discharge to sea, nor local rainfall variability. Actual watershed area level rainwater capture efficiency - aka "groundwater recharge" is not currently known. Cf. glossary precipitation comments.

• At the 2112 watershed's sea-outfall, Canyon Creek is the principle creek. Significant tributary creek systems, contributing seasonally include the Cascade, Coralroot, Cloud, Sky and N Canyon creek (see 2112 watershed area local detail map below).

• The natural, surface hydraulic systems of Ribbon, North Canyon Creek, Sky Creek and Cascade Creek (both creek systems and related wetlands) are impacted by ongoing infrastructure development in the central 2112 watershed area.

• Within the watershed area are approximately 55 groundwater wells, with no known springs. The existing well density current groundwater well usage, and potential well usage relate to ongoing development in a core, central, watershed area.

• The 2112 watershed is within the Musgrave, subsurface aquifer subregion.

* Impressive 2112 area field work by our dedicated local volunteer has led to a redifinition of one of the 2018 CRD watershed boundaries, with a significant addition to the watershed area in the northeast.

2112 Watershed - Upper Reaches

This watershed area extends between the watershed headwaters and Mountain Road.

• For the most upland 2112 watershed catchment area, no FWC watershed characterisation and field sampling data is currently available.

• The upper 2112 watershed catchment area contains several perennial and ephemeral creek systems

• About half the watershed area of N. Canyon Creek is in Crown lands, open to recreational use including hiking, 2- and 4-wheel drive off-road vehicles.

2112 Watershed Wetlands - Upper Reaches

This watershed wetland area is located around Skywater Drive.

• Multiple wetlands exist in the upper watershed catchment area, these are partly (largely?) located in an area with ongoing infrastructure development.

2112 Watershed Creeks - Lower Reaches

This watershed area extends between Mountain Road and the creek systems sea-outfall.

• The lower 2112 watershed catchment area contains several perennial and ephemeral creek systems

• The majority of the lower, downstream part of the 2112 watershed area comprises natural, forested ecosystems, within the protected Mount Tuam Ecological Reserve.

• The various 2112 watershed creek systems combine, within a significant canyon, into a single "S. Canyon Creek", discharging at a single sea-outfall, in Cable Bay.

• The watershed area of S. Canyon Creek and its tributaries’ lower reaches comprises second-growth forested ecosystems within the protected Mount Tuam Ecological Reserve.

2112 Creek Systems, Site Flow & Chemistry Data

The discrete 2112 creek catchment areas measured are characterised by significant flow and chemistry variability. Field notes from our local FWC volunteer:

Canyon Creek Area [1] North

A powerful year-round creek over five kilometres in length, Canyon Creek drops over 540m in elevation from its headwaters in wetland ponds beneath the peak of Hope Hill to sea outfall at Cable Bay. The upper half of its length is mapped as being within the Larlow Creek watershed, ending abruptly at a private pond just east of the Hope Hill Crown lands. This mapping error is likely due to the creek going underground, downstream from the pond, during the dry season before re-emerging near the entry of Sky Creek below the first switchback of Anna’s Drive.

N. Canyon Creek Area [1] North

Arising in the wetland basin east of the peak of Hope Hill, Canyon Creek zigzags steeply north through Crown lands in a series of bogs and bedrock ridges amid mixed second-growth forest with towering White Pine and the occasional old growth Douglas Fir. Entering recent clear-cut private lands it slows through a wetland forest and then falls gently southeast again in Crown lands along the north slope of Hope Hill above Musgrave Road. Dropping steeply again into private lands to the east, the creek flows through a man-made pond before dropping to a bench where it goes underground during the dry season. At Anna’s Drive it flows south-southeasterly into wetlands of the Mt Tuam Ecological Reserve then on a nearly straight line along a gentle gradient through fractured faultline bedrock to a culvert at Mountain Road.

S. Canyon Creek Area [1] South
At Mountain Road, the creek flows through an extensive gravel floodplain and cedar grove, then into a deep gorge with the first of a series of waterfalls and rocky rapids beneath towering firs, cedars, maples and the occasional old growth Douglas fir, tumbling a further 200m in elevation to sea outfall.

This creek, over 3 km in length, has a sizeable flow from rainfall, snowmelt and the multiple wetlands of the south Hope Hill basin. Possibly a permanent creek before the roadwork and clearing of the Skywater lands, it drops steeply through dense mixed second-growth forest of the Mt Tuam Ecological Reserve, passing over a series of cascading waterfalls for a total drop of about 400m before entering S. Canyon Creek. The largest and most impressive waterfall is within sight of Mountain Road, surrounded by cathedral maples and firs. Small pools above these falls can have measurable flows late into the fall.

NW. Cascade Creek Area [2] West
...

Cloud Creek Area [2] West
This transitory creek arises on the east slope of Mount Tuam near the entrance to the Skywater development, crosses under Anna’s Drive through multiple wooded wetlands and rock scree to enter N. Canyon Creek about 500m upstream from Mountain Road.

Ribbon Creek Area [2] West
This seasonal tributary is about two kilometres in length, running northwest to southeast, draining the steep, clear-cut slopes of the Mount Tuam Estates subdivision. Crossing Mountain Road west of the Cascade Creek waterfall, Ribbon Creek tumbles through mixed second-growth, slowing along gravel bars beneath towering maples before dropping into the Canyon Creek Gorge about 300m upstream from its sea outfall. During the high flows of the rainy-season, the creek makes a lovely ‘ribbon’ waterfall as it plunges into the gorge for a total drop of about 360m.

In the dry season this creek goes underground along most of its length except for small flows through fragmented bedrock pools above the waterfall. In 2022 these pools dried up in late September.

Coralroot Creek Area [3] East
This is another small tributary, little more than half a kilometre in length, aligned with a low escarpment running north-northwest to south-southeast, arising from wetland ponds east of Dubois Road. Traveling underground for most of its length except during the rainy season, parallel with an adjacent stretch of North Canyon Creek before entering it 100m north of the Mountain Road culvert. Along its lower reaches second-growth cedar groves provide habitat for coralroot, a perennial saprophytic plant in the orchid family.

Despite its short length and low flow, Coralroot Creek has proved to be perennial by setting a PVC pipe into the stream bed to capture the flow during the dry season (lowest reading: 0.005 l/sec in Sept. 2021).

Cabbage Creek Area [3] East
This is a small tributary about half a kilometre in length, aligned with a high escarpment west of the junction of Mountain and Lumley Roads and arising near its base. The creek descends gently through open second-growth mixed forest, forming boggy areas of skunk cabbage and cedar before cutting steeply through clay and silt to enter the Canyon Creek Gorge from the northeast about 500m upstream from sea outfall.

Despite its short length it has proved to be perennial by monitoring through the dry season using a PVC pipe set into the clay bed of the creek to capture its flow (lowest reading: 0.008 l/sec in Oct. 2021).

Of interest, a large swampy area north of the creek’s source was drained and diverted into Lumley Creek by early Hawaiian settlers. Might this wetland have been part of Canyon Creek watershed before the diversion? Could a related underground aquifer still feed Cabbage Creek?

S. Canyon Creek All watershed areas

The characteristics of both flow and chemistry of the S. Canyon Creek field site may reflect the dominance of one or more creek systems (eg Cascade Creek, or N. Canyon Creek), and underlying creek baseflow (groundwater inflow), or are the result of complex mixing "blending" across all catchment areas, as is seen at the Weston Creek watersheds sea outfall.

Note: FWC field data collected to-date does (yet) not characterise more complex hydraulic system variability related to groundwater system(s) changes, nor potential invisible pollutants. The former analysis needs the integration of surface (FWC) and subsurface (IT) datasets - work ongoing.

2112 watershed, lower reaches creek discharge locations (suitable for calibrating surface water outflow to sea parameters) are not available - winter flow conditions are not conducive to the maintainance of a permanent flow station (nor staff-gauge...) installation.