SSI FreshWater Catalogue - 9178 "Fernwood"

SSI FreshWater Catalogue

SSI, NORTH Watersheds

"9178" (Fernwood) Watershed "Notes"

- Hudson Point & Fernwood area -

Last update 2024/02/06

SSI North Area - overview watersheds (colour coded, CRD, 2018) & watershed note areas

North Island, "9178" ("Fernwood") Watershed

From our ongoing North Island, Freshwater Cataloguing - notes on the "9178" watershed area. Cf. the SSI FWC webmap for field locations and charted information (where available).

The content of these "Notes" entries is dependant on the information that is currently available, from FWC volunteer work, FWC reporting or from other sources. Additional volunteers in this area would be great!

Note - if you have additional insights into this area (the watershed, it's creeks or wetlands), can help with site(s) access, or are interested in being involved in data collection for this project area, please contact the SSIFWC Project Lead.

For now these notes draw heavily extracts from our monthly FWC "Which Creek Is It" Competition, from our Salt Spring Island FreshWater Catalogue Watershed Stewardship Group Facebook page, with "field note" addendums where additional information has become available. Additional volunteer resources will enable us to do more!

General Watershed & FWC Creek Information:

The October 2021 Which Creek Is It (WCIT) competition creek was Creek-to-be-named - X in our creek-to-be-named series… located in the "9178" watershed. Our January 2024 WCIT was Creek-to-be-named -XXXIX, located on Walkers Hook Road, close to the Fernwood Road junction Neither of these WCIT creeks are on the island’s published freshwater maps, and the “9178” watershed does not have an appropriate name. For ease of reference this 9178 watershed is referred to as Fernwood.

We have some 125+ samples collected over 2020-2024 by our FWC North Island watersheds stewardship team, with some help from our school “Team Fernwood” group, as a part of their 9178 Fernwood watershed reconnaissance coast walk. From our 9178 watershed FWC creeks field sampling dataset developed to-date, the creek systems are poorly known (and somewhat odd-ball).

In addition to the ongoing creek sampling we have started on there is still some freshwater catalogue stuff to do(!) on: sampling, area history research and some appropriate, and formal freshwater catalogue creek/watershed name(s) for this important north watershed area.

If you are interested in being involved in the fieldwork, or in the research and naming of our growing collection of unnamed island creeks, wetlands and watersheds please contact the SSIFWC Project Lead for further information.

The 9178 (Fernwood) Watershed

The 9178 (Fernwood) watershed is located along a beautiful and popular north Salt Spring Island coast (creek-to-be-named X may be a (the) single, significant surface creek watershed freshwater flow outlet - discharge to the sea.

The 9178 watershed receives something like 2,777,800,000 litres (733,817,000 gallons) of rainfall (precipitation, or surface water) per annum (water volumes are approximate with no consideration of surface/terrain conditions, nor rainfall variability within the catchment area)
The 9178 watershed’s size is not in-significant (about a tenth of the largest watershed on the island). In terms of its Ha size this watershed is “up-there” with Ganges Creek, 9076 (Cusheon Cove), 9117 (Reginald Hill) and others with a broadly equivalent size
There is no known surface (or subsurface) water district abstracting water from the 9178 watershed, ca. 80 known wells and a small number of licenced springs. The CRD managed, Highlands - Fernwood water system, providing drinking water to approximately 321 customers, actually abstracts water from St. Mary Lake (located in the Duck Creek watershed to the south)
Known freshwater licences for the 9178 watershed might be available here http://a100.gov.bc.ca/pub/wtrwhse/water_licences.input by entering a “stream name”. However, the linked BC water licences report treats all of SSI as a single watershed, so it is not possible to “pull” all freshwater licences in the “1983" watershed.

Historical & Other Watershed Insights:

TBD

Note - any other local insights, or interested in contributing to the historical/other notes on our islands' watersheds, please contact the SSIFWC Project Lead.

FWC "Citizen Science" Watershed Notes - Reporting:

It’s early days for any detailed working model(s) for the 9178 watershed, though some big picture observations/interpretations can be made:

The watershed has no visible/known year-round surface freshwater outflows and the 9178 Hudson Pt Ck Outfall (and others) flows for only a small part of the year so is classified as “ephemeral”
The absence of year-round surface may highlights the role of the island’s “water towers” in sustaining surface flow (groundwater base flow) during the summer months and/or says something about the area aquifer health. Anecdotally this "less freshwater in this watershed area area" may be supported by higher seasonal freshwater delivery frequencies and poorer wells?

Other, approximately equivalent-sized, island watersheds do have year-round creek flows or not… so perhaps the seasonal watershed flow story is more complex than water towers, geology, and surface cover and usage… TBD.

At this early stage in the FWC data collection/analysis, particularly perplexing is the chemistry data for the measured 9178 Hudson Pt Ck Outfall creek…

Geographically the 9178 watershed is an area of relatively low surface relief, with an extensive, established, farm/agricultural area over much of the northern part of the watershed. Geologically the local watershed geology (and subsurface aquifers) are mix of sedimentary rocks, with several significant through-going faults recorded (Greenwood & Mihalynuk, 2009).

Between prolonged no-flow, dry spells the "9178 Hudson Pt Ck Outfall" flow creek chemistry oscillates between very low conductivities (actually around that of distilled water… or measurement issues with higher salinities?), and very high conductivities. At this stage, ruling out field sampling issues and local anthropogenic factors impacting chemistry…, it is possible that the seasonal oscillations seen in this creek relate to very significant groundwater - surface freshwater variability/mixing.

A crude, inverse, relationship between creek water temperature and air temperature may indicate a seasonal groundwater contribution to the Hudson Pt Ck outfall system. However, there is no clear lower amplitude dry - wet seasonal trend visible in the FWC data collected to-date (unlike seasonal trends in most SSI creeks).

The end-member chemistry (range) observations seen in the 9178 Hudson Pt Ck outfall close to its outfall are unlike any of the patterns (or extremes) seen in other FWC measured island creeks (aka it's a real odd-ball!), which suggests other “external factors may play a role. The creek’s position (height above sea-level) precludes any direct (surface) saline incursion into the creek at the FWC field sampling location. However, the creeks' source (and path) at/close to a through-going NNW-SSE fault, provide a possible candidate for influencing the chemistry signature variability, with two(?) possible scenarios:

1] The geology of the area (Ganges Formation mudstones) and groundwater flow through fractured mudstones may lead to more mature groundwaters (baseflow) in the general watershed creek drainage area. These groundwaters might be characterised by higher concentrations of chlorides, the result of the release of key NA and CL ions within the mudstones, and from mixing between groundwater and seawater (cf. Allen & Matsou 2002)… enhanced by the fault?

A model of fresh groundwater mixing with pre-existing, more saline (geologically older) groundwater seems less likely given that this single creek shows the anomalous chemistry behaviour.

2] Saltwater intrusion along the local fault systems contributes to Hudson Pt. creek chemistry fluctuations (faults and fractures being potential conduits for saltwater intrusion pathways). Perhaps, with saline intrusion reinforced/perturbated by tidal, sea water flux along these same fault systems (it does happen!). The link to the island's northern “salt springs” is a yet to be determined, though a connection between springs and faults is well known, and the famous island's "salt springs" are intriguingly close!

Collecting more data (and closely monitoring measurements and measurement device calibration) may help to refine our understanding of the Hudson Pt Ck “chemistry anomalies”, including an investigation of local wells for potential local coastal salinisation effects. A working model(?) - the ephemeral, Hudson Pt Ck outfall flow chemistry, may (indirectly) be tidally influenced with surface fresh/salt water and coastal groundwater blending being facilitated by along thorough-going fault movement?

FWC Images and Videos:

9178 (Fernwood) Watershed FWC field images. Note - all FreshWater Catalogue images & videos copywrite belongs with the WPS and the FWC. We are grateful for due acknowledgement of copywrite in any use or publication of these educational resources.

Other Local Area Resources:

Allen, D. M., and Matsuo, G. P., 2002., Results of the Groundwater Geochemistry Study on Hornby Island, British Columbia.
Greenwood, H. J., & Mihalynuk, M. G., 2009., BC Geological Survey, Open File 2009-11 Salt Spring Island Geology.
Klassen, J. & Allen, D. M. 2016., Risk of Saltwater Intrusion in Coastal Bedrock Aquifers: Gulf Islands, BC.

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