Wetland Classification and Geologic Assessment Report:

Gabriola Island Water Region (WR7-GI)

Prepared for:

Regional District of ’s Drinking Water and Watershed Protection Program

Prepared by:

Mount Arrowsmith Biosphere Region Research Institute

December 2019

Wetland Classification and Geologic Assessment Report: Water Region

Acknowledgments

A special thank you is extended to Julie Pisani, Coordinator of the Drinking Water and Watershed Protection Program (DWWP) at the Regional District of Nanaimo (RDN), for her continual support and guidance throughout this project. We would also like to thank our team of advisors for this project including, Island University (VIU) Geography Department faculty member and RDN DWWP Technical Advisory Committee board member, Dr. Alan Gilchrist PhD PGeo., as well as VIU Earth Science Department faculty member, Dr. Jerome Lesemann PhD.

Another special thank you to former Project Coordinator of the Mid- Habitat Enhancement Society (MVIHES) and lifelong active community member and environmental steward, Faye Smith Rosenblatt. Her passing has been a great sadness and we are exceedingly grateful for the care and contributions she made to this research project and to the Mount Arrowsmith Biosphere Region (MABR) as a whole. We would like to extend further thanks to Bernd Keller, member of MVIHES, for his continual support and collaboration with this project moving forward.

We continue to be thankful to the members of the public and property owners for welcoming our researchers on to their lands to conduct our research, as well as for engaging and showing interest in the purpose and longevity of this project.

Research Project Team

Wetland Project Coordinators Research Assistants Jessica Pyett Alanna Vivani Haley Tomlin Jenica Ng-Cornish Ashley Van Acken

GIS & Remote Sensing Specialists Ariel Verhoeks

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

Table of Contents

1.0 Introduction 6 2.0 Methods 7 - 9 2.1 Preliminary Research Steps 7 - 8 2.2 Field Steps 8 - 9 3.0 Regional Description 9 - 12 3.1 Physiography 9 3.2 Regional Geology 9 - 12 3.2.1 Bedrock Geology 9 - 11 3.2.2 Stratigraphic Framework 11 - 12 4.0 Gabriola Island Water Region Study Sites 12 - 19 4.1 Gabriola Island 12 - 13 4.1.1 Surficial Materials Gabriola Island 13 4.1.2 WR7-GI-01 Wetland Observations and Classification 13 - 14 4.1.3 WR7-GI-02 Wetland Observations and Classification 15 4.1.4 WR7-GI-03 Wetland Observations and Classification 16 - 17 4.1.5 WR7-GI-04 Wetland Observations and Classification 17 - 18 4.1.6 WR7-GI-05 Wetland Observations and Classification 18 - 19 5.0 Discussion 20 - 24 5.1 Hydrostratigraphy 20 - 21 5.2 Wetland Characteristics 21 - 22 5.3 Recommendations 22 - 24 5.3.1 Cross-Sectional Analysis 22 - 23 5.3.2 Geophysical Surveys 23 5.3.3 Installation of Instrumentation 23 - 24 6.0 Conclusion 24 7.0 References 25 - 27

Appendix A: Summary of Wetland Classification and Aquifer Characteristics 28 Appendix B: Mapped Aquifers in the Gabriola Island Water Region 29

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

List of Figures

Figure 1: Wetland Sites within the Gabriola Island Water Region 7

Figure 2: Simplified Stratigraphic Units of the Nanaimo Group 11

Figure 3: Late Quaternary Deposits and Corresponding Event Sequence 12

Figure 4: WR7-GI-01 14

Figure 5: WR7-GI-02 15

Figure 6: WR7-GI-03 17

Figure 7: WR7-GI-04 18

Figure 8: WR7-GI-05 19

Figure 9: Example Distribution of Materials and Their Relationship to 21 Stratigraphy and Hydrostratigraphy

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

Abstract Significant data gaps exist within the Regional District of Nanaimo (RDN) in regards to wetland locations, classifications, and what role they have in groundwater recharge. While there has been recent interest in regional freshwater resources within the RDN’s watersheds, there are relatively few studies that have inventoried wetlands and investigated their localized connection to groundwater resources. Our objectives in this study were to: 1) ground truth predictive mapping that showed the distribution of potential wetland sites in the Gabriola Island Water Region; 2) create an inventory of wetlands in the Gabriola Island Water Region; and 3) evaluate each site’s hydrogeological position to gain a better understanding of water storage, discharge, and potential flow pathways at each site. Researchers found that there were various types of wetlands in the region including swamps, marshes, bogs, and shallow water. Many of these systems had secondary classifications that were unique to each site as a result of localized conditions. At the time the sites were visited, most of the wetlands contained water or had diffuse or central patches of water. By monitoring the health of these systems and investigating subsurface conditions through desktop analysis, geophysical surveys, and instrumentation, it should be possible to develop new management practices while also identifying any potential connections between surface water and groundwater systems. It should be noted that wetlands were mapped based on accessibility and permission from landowners; these findings may not be representative of all wetlands that exist across the entire water region. Overall, results from this study will provide a framework for understanding how localized wetland systems contribute to both local and regional freshwater systems, while also informing land use and planning decisions across the RDN.

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

1.0 Introduction

The Regional District of Nanaimo (RDN) is located on the eastern coast of Vancouver Island, . Geographically, the RDN comprises an area that extends from the northern point of Deep Bay to the southern point of Cedar and includes Gabriola, Mudge, and DeCourcy Islands. There are four municipalities within the RDN that are home to over 155,000 people and include the City of Nanaimo, District of Lantzville, City of Parksville, and Town of Qualicum Beach (Regional District of Nanaimo, 2019a). Seven major water basins divide this area and are referred to as water regions in this report. The water regions include: Big Qualicum, Little Qualicum, French Creek, Englishman River, South Wellington to Nanoose, Cedar-Yellow Point/, and Gabriola Island (Waterline Resources Inc., 2013). This document focuses on Water Region 7 (WR7), the Gabriola Island Water Region (Figure 1). WR7 encompasses an area of approximately 5,636 ha and is comprised of three of the southern sub-group of : Gabriola, DeCourcy, and Mudge, all populated islands off of the east coast of Nanaimo (Regional District of Nanaimo, 2019b). This report will discuss wetlands mapped in this region and connect field observations with literature to better understand impacts of surrounding land uses while also developing a better understanding of potential connections between surface water and groundwater systems. To accomplish this, our report will highlight field methods used for wetland mapping, the physical geography and ecology of each wetland, as well as regional geology, with a focus on the hydrology and surrounding land uses. Developing baseline data on the ecological and geological relationships within wetlands will be crucial when trying to understand local impacts on ecology, as well as hydrological processes associated with groundwater recharge.

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

Figure 1: Wetland Study Sites in Gabriola Island Water Region. Note DeCourcy Island is not shown. Sources: Imagery obtained from Esri’s online basemap database; water region boundaries obtained by the Regional District of Nanaimo; wetland site data collected in the field; map developed by MABRRI.

2.0 Methods

2.1 Preliminary Research Steps

Prior to mapping a wetland in the field, the following preliminary research steps were taken:

1. Review predictive wetland maps that were created using Geographic Information Systems (GIS) and remote sensing based on existing data from Ducks Unlimited Workflow that combines the Government of British Columbia’s Sensitive Ecosystem Inventory (SEI), Pacific Estuary Conservation Program (PECP) polygons, and the Fresh Water Atlas (FWA) to determine the location and predictive classification of each site.

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

2. Determine which water region each wetland is located in using GIS software, specifically ArcMap 10.5, and associated RDN Water Region layers (RDN, 2018).

3. Identify proximal aquifers, including their classification number, type, level of demand, productivity, and vulnerability. This was completed using GIS software and associated groundwater layers provided by the Government of British Columbia’s Ministry of Environment (n.d.).

4. Review topographic maps, surficial deposit maps, well drilling data, satellite imagery, and GIS data to establish drainage basins, as well as localized inflows and outflows at wetland sites to provide an aerial perspective of the physical traits of each wetland.

5. Review satellite imagery to determine adjacent land uses to each wetland site.

6. Review parcel identification numbers provided by the RDN to determine property ownership in order to determine accessibility to wetland sites.

7. Create field maps of each wetland site with a determined scale and Universal Transverse Mercator (UTM) coordinate system.

8. Determine points of access on field map and potential wetland boundaries prior to visiting each site.

Once the preliminary research was completed and permission had been granted from property owners allowing researchers access to their land, the team conducted field work to map and classify each site. Field methods and standards were adopted from the British Columbia Wildlife Federation’s (BCWF) WetlandKeeper’s long form survey.

2.2 Field Steps

When entering the field, the following steps were taken to ensure data was accurately recorded:

1. Data recorded on the BCWF wetland long form survey includes: current weather, wetland coordinates, wetland size and dimensions, site classification, functionality, dominant adjacent land use, hydrology, surrounding vegetation, surficial deposit composition, impacts or disturbances, wetland management, photographs, wetland sketches, vegetation transect surveys with quadrats, and soil observations taken from samples that were collected using a 30 cm auger. The number of transects completed at each site varied based on the complexity of vegetation at each system; the more complicated sites had an increased number of transect lines to ensure vegetation data was

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

representative. Along transect lines, quadrats were placed in the middle of each wetland zone to identify shrubs, herbs, and tree cover.

2. Identify sites where bedrock or surficial deposits are exposed and record compositional characteristics to understand how water may infiltrate groundwater. Researchers would also attempt to conceptualize if and where seepage may be occurring at localized sites. This was done using surficial geology maps created by Jan Bednarski (2015).

3. Ground truth where inflows and outflows may be at each wetland site and record waypoints at these locations using GPS units.

4. Record a GPS track of the wetland’s perimeter, which can be compared to Ducks Unlimited data and predictive mapping (2016) to interpret any observable changes in wetland shape and size. In some cases, the lines of the perimeter were later smoothed in the office using GIS software to allow for a more representative track that follows the wetland boundary between vegetation zones. The wetland dimensions were also measured by using both the perimeter data and GIS software.

3.0 Regional Description

3.1 Physiography

Synonymous to the rest of the RDN, WR7 is characterized by mild, dry summers and cool, wet winters. However, annual precipitation amounts vary across the RDN and are often wetter in northern, inland regions compared to southern coastal areas (RDN, 2012). One climate station is active on Gabriola Island, with the mean annual precipitation being 958 mm (Burgess & Allen, 2016). The Coastal Douglas- fir (subzone: moist maritime [CDFmm]) is the only biogeoclimatic ecosystem classification (BEC) zone present within the Gabriola Island Water Region. The BEC zones encompass ecosystems with uniform microclimates, vegetation, and soils (MacKenzie & Moran, 2004). These environmental characteristics often control how surface and groundwater systems are able to interact. Furthermore, understanding these interactions is critical as the community of Gabriola Island relies on groundwater resources as the primary source for irrigation and drinking water (Regional District of Nanaimo, 2019b).

3.2 Regional Geology

3.2.1 Bedrock Geology

The southeastern portion of British Columbia is a crustal segment of the Wrangellia Terrane, part of the larger Insular Belt that accreted onto the east coast of British Columbia in the Cretaceous Period

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

(~100 million years ago (Mya)) (Bednarski, 2015). The formation of Vancouver Island began in the Devonian Period (~380 Mya) with deep oceanic volcanism forming the oldest Sicker Group rock formation (Yorath, 2005). Layers of limestone accumulated overtop during the Carboniferous/Permian Periods (~245 Mya). The most prominent formation, Karmutsen basalt, intruded through these basement layers in the Triassic Period (~230 Mya) and was once again covered by shallow marine limestone formations. Volcanism governed the Jurassic Period (~200 Mya) and was followed by the intrusion of granitic plutons that account for much of Vancouver Island’s large mountain ranges today (Yorath, 2005). The Georgia Basin, which separates Vancouver Island from the North American continent, evolved through subduction-related lithospheric down-warping of the Wrangellia Terrane (England, 1989). Approximately 42 Mya, subduction also lead to the collision of a series of Pacific seamounts with Vancouver Island, adding crustal terrane to the Island, and resulting in further down-warping (Doe, 2009). The collision pushed Vancouver Island closer to the mainland and crumpled the seafloor of the Georgia Basin. The folding of alternating sand- and shale-dominated units which comprised the seafloor of the Georgia Basin formed the Gulf Islands. The uplift and mountain building that was associated with the continent-continent collision and formation of Vancouver Island also lead to rapid erosion and high sediment production, followed by depositional events that are identified as the Nanaimo Group sedimentary rocks. The units of the Nanaimo Group were deformed by post depositional strike-slip and thrust compression (Yorath, 2005). These deformation events made it possible for the east/northeast dipping beds of lower stratigraphic position to outcrop at the surface. The Nanaimo Group rocks are subdivided into 11 formations that were deposited between North America and Wrangellia (Figure 2) (Bednarski, 2015). They were formed by fluvial processes and deposited as a sedimentary gradation of conglomerate, sandstone, shale, and coal (Bednarski, 2015). Within our study area, 6 formations are predominate: Gabriola, Spray, Geoffrey, Northumberland, de Courcy, and Cedar District (Hodge, 1978). Gabriola, Geoffrey, and de Courcy formations are mainly comprised of sandstone, Spray and Northumberland formations are mainly mudstone, and Cedar District formation is a mix of mudstone and sandstone. It is the Nanaimo Group that predominantly underlies the study area and therefore is pertinent to the wetlands in this water region.

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Figure 2: Simplified Stratigraphic units of the Nanaimo Group (Hamblin & McCartney, 2014).

3.2.2 Strategic Framework

The regional bedrock geology in low lying areas on Vancouver Island and surrounding region has been overlain by unconsolidated materials that reflect past environmental conditions. These sediments vary in lithology, thickness, and extent (Bednarski, 2015). Depth varies locally, from thick blankets of unconsolidated material to sparse, discontinuous packages that expose bedrock at the surface (Bednarski, 2015). Stratigraphic packages were deposited by the Cordilleran Ice Sheet (CIS) and are characteristic of glacial processes such as reworking and erosion (Bednarski, 2015). Any prior unconsolidated materials were generally eroded by the last glaciation, marking a discontinuity in the geological record. Many of the medium-course grained sediment layers act as productive aquifers for areas surrounding the region, although in WR7 the majority of water is stored in bedrock aquifers (Regional District of Nanaimo, 2017). Understanding the extent and thickness of unconsolidated materials is essential for mapping

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

potential groundwater recharge zones. The lithostratigraphic deposits found on Vancouver Island and the surrounding region include Salish Sediments, Capilano Sediments, Vashon Drift, Quadra Sand, Cowichan Head Formation, and Dashwood Drift (Figure 3).

Figure 3: Late Quaternary Deposits and Corresponding Event Sequence (Bednarski, 2015).

4.0 Gabriola Island Water Region Study Sites

4.1 Gabriola Island

Gabriola Island Water Region contained five study sites of interest; all located on Gabriola Island. The island has an area of 5,773 ha and a maximum elevation of 160 m above sea level (, n.d.). The majority of land uses on the island are small and large rural residential, agriculture, and parks. There are very few water bodies on Gabriola Island, the largest being Hoggan Lake (Burgess & Allen, 2016). According to literature, most of the wetlands on the island are seasonal, and only a few are observed year round. All of the wetland study sites were located on top of bedrock aquifer 709 IIA (15) (Appendix B). Aquifer 709 has high vulnerability and moderate demand (GW Solutions Inc., 2017). Additionally, in the last five years of data, the water level trend is declining at a moderate to large rate of decline (GW Solutions Inc., 2017).

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

All of the study sites were located on private property and required permission from landowners to access the land. In most cases, the wetland bordered several different private properties, so only the portions with permission were mapped.

4.1.1 Surficial Materials of Gabriola Island

The most recent glacial period that covered Vancouver Island and the surrounding area is responsible for the surficial material that comprises most of the region. On Gabriola Island, marine and glaciomarine veneers are found overlying bedrock across most of the island, usually consisting of loam and clay (Geological Survey of , 1963). Wetlands WR7-GI-04 and WR7-GI-05 are located in areas that are dominated by marine and glaciomarine surficial sediments (Geological Survey of Canada, 1963). In some areas of Gabriola Island, veneers (less than 1 m in thickness) of deltaic, fluvial, and upland swamp Salish Sediments (Figure 3) are also found, comprised of gravel, sand, silt, clay, and peat (Geological Survey of Canada, 1963). Surficial material proximal to wetlands WR7-GI-01, WR7-GI-02, and WR7-GI-03 are dominated by Salish Sediments (Geological Survey of Canada, 1963). Drilling data from wells 89846, 85025, 73010, 72986, and 73244, which are located near the wetland sites support Geological Survey of Canada (1963) data with well logs that show sandstone and shaley sandstone present to depth of 54 to 60 m (Government of British Columbia, n.d.). This represents upper Nanaimo Group sandstone, indicated by the Geological Survey of Canada (1963) as bedrock. Data from wells 73010, 72986, and 73244 supports the presence of sandstone to a depth of approximately 60 m, with the presence of a 0.5 to 2.5 m thick overburden, likely representing a veneer of Salish Sediments (Government of British Columbia, n.d.).

4.1.2 WR7-GI-01 Wetland Observations & Classification

WR7-GI-01 on South Road was evaluated on October 10, 2019. The wetland is situated on several different private properties; researchers only had access to two properties (Figure 4). In total, the wetland occupies approximately 6 ha of land, based on approximations of the length (262 m) and width (389 m) using GIS software. Perimeter boundaries were approximated from predictive mapping created from the Ducks Unlimited Workflow, Sensitive Ecosystem Inventory, Fresh Water Atlas, and the Pacific Estuary Conservation Program (Figure 4). The study site is located approximately 72 m above sea level (Appendix A, Table 1).

During the site visit, researchers classified the two properties as different systems. The first property was classified as dominant swamp due to the dense distribution of hardhack (Spiraea douglasii) in the center of the wetland. Surrounding the hardhack, the dominant flora was Douglas-fir (Pseudotsuga menziesii), red alder (Alnus rubra), red osier dogwood (Cornus sericea), baldhip rose (Rosa

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

gymnocarpa), salal (Gaultheria shallon), bracken fern (pteridium aquilinum), and skunk cabbage (Symplocarpus foetidus). The second property was classified as dominant bog. Although most of the vegetation was cleared for farmland, researchers did record an abundance of Labrador tea (Ledum groenlandicum) and various sphagnum mosses. There was no water present during the site visit; therefore transition zones were distinguished by vegetation. The system appeared to be natural, and there were no noticeable inflows or outflows present. Surrounding land uses included rural residential and agriculture. Researchers collected two soil samples in the swamp wetland to better understand the distribution of sediments. Both samples had very strong decomposition with plant structures being almost unrecognizable. On the edge of the wetland, a third soil sample was collected and a grey-white band (~7.5 cm thick) of diatomaceous earth was present. Diatomaceous earth is the fossil remains of a type of pond algae called diatoms, and is commonly found in wetlands and lake beds on Gabriola Island (Doe, 2010).

Figure 4: WR7-GI-01. The sections of the orange parcels that intersect the red wetland perimeter indicate the sections of the wetland that field data was collected for. Sources: Imagery obtained from Esri’s online basemap database; wetland perimeter data obtained from Ducks Unlimited Workflow; map developed by MABRRI.

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

4.1.3 WR7-GI-02 Wetland Observations & Classification

The second study site, WR7-GI-02, was mapped on October 25, 2019 and is located approximately 72 m above sea level (Appendix A, Table 1). Using GIS software, the dimensions of the wetland were calculated and are, on average, approximately 182 m in length and 206 m in width (Figure 5). Similar to WR7-GI-01, the wetland is located on several different private properties; researchers had access to four of those surrounding this wetland. The study site appears to be natural, and a creek runs through the center of the wetland. Emergent vegetation was present in the creek, the water clarity was very clear and yellow-brown in colour; it had a pH of 5.5 and the surface water temperature was 10°C. Seasonal water deficits likely occur within this study site and would need to be confirmed through long- term monitoring. Researchers classified the system as a dominant swamp. Swamp areas contained dense hardhack, Himalayan blackberry (Rubus armeniacus), salmonberry (Rubus spectabilis), and sword fern (Polystichum munitum). Three soil samples were taken within swamp sections; they contained silty loam or silty clay loam with no organic layer, all dark brown in colour.

Figure 5: WR7-GI-02. The sections of the orange parcels that intersect the red wetland perimeter indicate the sections of the wetland that field data was collected for. Sources: Imagery obtained from Esri’s online basemap database; wetland perimeter data obtained from Ducks Unlimited Workflow; map developed by MABRRI.

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Wetland Classification and Geologic Assessment Report: Gabriola Island Water Region

4.1.4 WR7-GI-03 Wetland Observations & Classification

The third wetland, WR7-GI-03, is located adjacent to Dunshire Drive and is 86 m above sea level. The wetland is approximately 142 m long and 215 m wide, on average; this was determined using GIS software (Figure 6). Researchers mapped the study site on October 25, 2019 and classified the system as a dominant swamp with secondary shallow water characteristics. WR7-GI-03 appeared to be a natural wetland. Like many of the other study sites, the wetland is located on several private properties; researchers had access to four properties so only a small portion of the wetland was mapped. Water appeared to pool in central sections of the system with diffuse patches of water throughout other areas. Researchers did not identify any inflows or outflows. The surrounding land uses are rural residential.

Dominant vegetation within the swamp region included hardhack, salal, red osier dogwood, Western red cedar (), trailing blackberry (Rubus ursinus), slough sedge (Carex obnupta), skunk cabbage, deer fern (Blechnum spicant), and bracken fern. The edges of the central shallow water contained a mix of hardhack, common reed (Phragmites australis), and several other grass species. Some grass species were also present as emergent vegetation in the center of the shallow water body. Although floating aquatic vegetation were not observed in the shallow water, researchers noted that it would likely be present in the warmer months. Three soil samples were taken; two in the swamp region and one in close proximity to the shallow water. Soil samples in the swamp region contained thick mud that was well decomposed. In the shallow water, decomposition was weak. Water was yellow-brown in colour with a temperature of 7°C and a pH of 5.5 in the swamp section. The water’s colour remained the same in the central shallow water region, but was 6.5°C and had a pH value of 5.8. Researchers spoke to the property owners who suggested that the system experiences seasonal water level fluctuations, but shallow water in the central section of the wetland remains year-round.

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Figure 6: WR7-GI-03. The sections of the orange parcels that intersect the red wetland perimeter indicate the sections of the wetland that field data was collected for. Sources: Imagery obtained from Esri’s online basemap database; wetland perimeter data obtained from Ducks Unlimited Workflow; map developed by MABRRI.

4.1.5 WR7-GI-04 Wetland Observations & Classification

Wetland WR7-GI-04 was mapped on October 25th, 2019 and was situated approximately 80 m above sea level. The wetland system is approximately 2 ha in size, having been measured using GIS to be approximately 68 m long and 349 m wide on average. Researchers classified the wetland was a dominant marsh. Outer sections of the site were densely populated with , salal, Oregon grape (Mahonia aquifolium), bracken fern, and English holly (Ilex aquifolium), an invasive species. The dominant species within the marsh area included sedges, grasses, and cattail (Typha latifolia). The central area of the wetland held deep water and thick mud that was unsafe for researchers to access, therefore vegetation observations were taken from the wetland shoreline. It was uncertain if the water level experiences seasonal fluctuations and it is recommended to re-visit the site during the seasonally dry months. Water samples in the marsh region contained clear, yellow-brown water and had a temperature of 6°C and a pH

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value of 6.2. One soil sample was collected and contained somewhat distinct fibrous organics that transitioned into a layer of clay. The wetland appears to be a natural system, however the site has undergone minor modifications. For example, a gravel road was built on the western edge to access a private property. As well, the system is adjacent to a busy road that may cause it to be at risk of pollution. Overall, the system appeared to be a functioning wetland.

Figure 7: WR7-GI-04. The sections of the orange parcels that intersect the red wetland perimeter indicate the sections of the wetland that field data was collected for. Sources: Imagery obtained from Esri’s online basemap database; wetland perimeter data obtained from Ducks Unlimited Workflow; map developed by MABRRI.

4.1.6 WR7-GI-05 Wetland Observations & Classification

The fifth wetland, WR1-BQ-05, was accessed from Chernoff Drive and is 162 m above sea level. The wetland is approximately 152 m long and 280 m wide, on average. Researchers mapped the wetland on October 4th, 2019 and classified the system as a dominant swamp. The system appeared to be a functioning and natural wetland that contained diffuse patches of ponds and potholes. There were no apparent inflows or outflows observed during the site visit; therefore, it is likely that the wetland

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experiences seasonal fluctuations based on precipitation and water table levels. In the central swamp sections, skunk cabbage was recorded sparingly through areas of dense hardhack. The outer sections of the wetland were dominated by Western red cedar, Douglas fir, and Western hemlock (Tsuga heterophylla). A soil sample was collected in the central section that appeared light-medium brown in colour and consisted of almost no decomposed organics and clay. Adjacent to the wetland was a large field area used by residents for recreation. Other dominant surrounding land uses include rural residential development, a sand and gravel pit, and forestry.

Figure 8: WR7-GI-05. The sections of the orange parcels that intersect the red wetland perimeter indicate the sections of the wetland that field data was collected for. Sources: Imagery obtained from Esri’s online basemap database; wetland perimeter data obtained from Ducks Unlimited Workflow; map developed by MABRRI.

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5.0 Discussion

5.1 Hydrostratigraphy

Hydrostratigraphy is the identification of mappable bedrock or unconsolidated materials on the basis that they have a set of hydraulic properties that allow them to behave like an aquifer or aquitard (University of Saskatchewan, 2014). These units have considerable lateral extent and also form a geologic framework for a distinct hydrogeologic system (University of Saskatchewan, 2014). Understanding the distribution of surficial materials and local bedrock units is critical when trying to understand the flow of surface water and groundwater systems.

As discussed in Section 3.2 Regional Geology, WR7 has undergone a series of climatic changes. As a result, environmental shifts have created complex local hydrologic and hydrogeologic systems across the RDN. Surficial deposits in WR7 reflect the glacial and postglacial processes that took place during the Quaternary period (Geological Survey of Canada, 1963). In most places, glaciers that overrode the area contributed to eroding rock surfaces and development of longitudinal valleys (Geological Survey of Canada, 1963). However, much of the area was mantled with unconsolidated materials during glacial retreat, as sea level was significantly higher than present levels (Geological Survey of Canada, 1963). Areas below the marine limit, situated further away from active fluvial systems, were mantled with marine and glaciomarine deposits that are known to act as local aquitards as they have reduced porosity, permeability, and hydraulic conductivity (Bednarski, 2015; Freeze & Cherry, 1979). Glaciomarine deposits have been known to vary in extent and thickness regionally, allowing bedrock to be exposed at the surface in many areas (Geological Survey of Canada, 1963). Sediments proximal to active fluvial systems were significantly different than the rest of the study area. The fluvial and glaciofluvial sediments that dominated areas adjacent to major river courses are known to have high porosity, permeability, and hydraulic conductivity properties (Geological Survey of Canada, 1963); (Freeze & Cherry, 1979). Figure 9 illustrates a simplified distribution of sediments and how their stratigraphy, lithology, and hydrostratigraphy are related; Nanaimo Group bedrock units are labeled as aquitard units based on the understanding that lithified bedrock typically has low permeability and porosity (Freeze & Cherry, 1979).

The main bedrock formations observed in the area are of Nanaimo Group origin; these units have been exposed at the surface as a result of tilting, faulting, and folding from accretionary processes (Hamblin & McCartnery, 2014). These deformation events have led to extensive fracturing of all major bedrock units allowing for a dramatic increase in fracture porosity, permeability, aperture size, hydraulic conductivity, and transmissivity (Hamblin & McCartnery, 2014). These fractures have allowed relatively impermeable bedrock units to have moderate to high aquifer potential (Hamblin & McCartnery, 2014);

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(Freeze & Cherry, 1979). Overall, bedrock and sediment outcrops were not prominent at localized wetland study sites but both play an integral role in controlling localized surface and groundwater interactions.

Figure 9: Example distribution of materials and their relationship to stratigraphy and hydrostratigraphy.

5.2 Wetland Characteristics

Swamps, marshes, bogs, and shallow water were the distinct wetland systems identified in WR7. Four of the five study sites were classified as dominant swamp systems (WR7-GI-01, WR7-GI-02, WR7- GI-03, and WR7-GI-05) with a secondary classification or in one case an equal bog dominant classification (WR7-GI-01). The other wetland was classified as a dominant marsh (WR7-GI-04).

Swamp wetland systems are characterized by high cover of tall shrubs and trees, as well as a well-developed herb layer (MacKenzie & Moran, 2004). There are typically two distinct types of swamps found in British Columbia – one that is characterized by a tall shrub physiognomy and the other is forested (MacKenzie & Moran, 2004). Wetland study sites WR7-GI-01, WR7-GI-02, WR7-GI-03, and WR7-GI-05 were classified as dominant swamp wetlands with tall shrubby vegetation (e.g. hardhack). Study site WR7-GI-01 was also classified as dominant bog due to its abundance of sphagnum species in a different section of the wetland. Bogs typically consist of shrubby or treed peatlands that have distinct communities of nutrient-poor shrubs and sphagnum species (Southam & Curran, 1996). Furthermore, site

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WR7-GI-03 had secondary shallow water classifications due the large area of stagnant water in the centre of the wetland (Southam & Curran, 1996).

WR1-GI-04 was classified as a marsh wetland, which significantly differs from swamps or bog systems. Marshes are often shallowly flooded and are dominated by emergent grass-like vegetation (Southam & Curran, 1996). Study site WR1-BQ-04 was flooded with water and contained distinct marsh vegetation, including: cattails, sedges, and grasses. Typically, marsh systems have low species diversity and strong dominance by a few key species, which was reflected at WR1-GI-04 (MacKenzie & Moran, 2004).

5.3 Recommendations

The purpose of the study was to map and classify wetland systems across the Gabriola Island Water Region, highlighting the stratigraphic framework of the region to better understand how study sites may be contributing to groundwater recharge. In order to move forward with developing an accurate groundwater flow model and understanding how wetlands are connected to groundwater systems in WR7, it will be necessary to conduct further desktop analysis and field research, including: cross-sectional analysis, well observation analysis, geophysical surveys, and installation of instrumentation. Further research and analysis will also need to be conducted to understand the functionality of particular wetlands and how surrounding land uses affect these systems.

5.3.1 Cross-Sectional Analysis

To date, field visits have been undertaken to gain an initial understanding of wetland classifications, potential sediment and bedrock types, and local topography within the Gabriola Island Water Region. In order to determine subsurface geology at a local scale, further research will need to be conducted using well locations and tag numbers in the area, which can be accessed from the BC Water Resource Atlas. By using well tag numbers, researchers will be able to retrieve detailed descriptions of the selected wells from the Government of BC’s (n.d.) WELLs database. Well records show the distribution of materials that were encountered during drilling. Moving forward, researchers will need to draw multiple cross-section lines across each prioritized study site to best capture the subsurface variability. By using wells located proximal to cross-section lines, researchers will be able to draw both stratigraphic and hydrostratigraphic cross-sections of the area, which would capture a snapshot of the geologic setting. More specifically, cross section would show surficial deposits, bedrock, as well as aquifer, aquiclude, and aquitard potential. Qualitative findings will make it possible for researchers to develop a working stratigraphic and hydrostratigraphic interpretation of each study site that can be used to

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hypothesize where water may be infiltrating the subsurface. It is these qualitative findings and hypotheses that will lead to further investigations to quantify groundwater recharge.

5.3.2 Geophysical Surveys

Geophysics is an interdisciplinary physical science that applies the knowledge and techniques of physics, mathematics, and chemistry to understand the structure, subsurface, and dynamic behavior of the earth and environment (Reddy, 2017). Geophysical techniques will be a tool that researchers can use to better understand the distribution of surficial materials within specific study sites in WR7. There are three potential geophysical techniques that can be used to understand subsurface materials: ground-penetrating radar (GPR), seismic refraction, and electrical resistivity (RSK, n.d.). Each of these methods require the establishment of survey lines. Survey line locations will be determined based on surficial deposits, proximity to surface water, and the ability to run a straight line in a safe manner. GPR data can be used to determine the location of the water table within upper unconfined aquifer units that may be present. GPR can also be used to determine aquifer saturated thickness and extent. In contrast, seismic refraction can be used to determine the structure of the subsurface, including the location and extent of sediment aquifers, clay aquicludes, and any present bedrock aquitards (Zelt et al., 2006). Furthermore, electrical resistivity can be used to determine the presence of water in sediment aquifers and is beneficial when assessing any regions that have confining layers situated above and below stacked aquifers (Collins et al., 2013). Although subsurface geophysical techniques cannot replace test drilling to understand surficial deposit distributions, they may lead to a better interpretation of stratigraphic units within a localized context. This knowledge can contribute to understanding how water is able to flow from the surface into the subsurface. It should be mentioned that test drilling is not a current recommendation due to budget constraints.

5.3.3 Installation of Instrumentation

The study of groundwater involves many complex disciplines and principles, and is considered to be a quantitative science (Freeze & Cherry, 1979). For this reason, it is critical to install instrumentation to better understand qualitative data that has been collected by researchers. Prior to mapping Gabriola Island, wetland sites from the other six water regions in the RDN, previously mapped, were prioritized based on a wetland’s proximity to observation wells, climate stations, hydrometric stations, fish bearing streams, and water right licenses. Using these parameters, a GIS analysis selected eight wetlands and ranked them. From those eight wetlands, two of them were not selected, based on their proximity to the ocean and their elevation; these sites could potentially be characterized as salt marshes and are less representative of the freshwater system. As a result, the remaining six sites were selected to be mapped seasonally as part of a long-term monitoring plan and one of the sites in Big Qualicum Water Region 1

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was chosen to install instrumentation as part of a pilot project to better understand the local hydrology of the site.

On October 30th, 2019, the instrumentation pilot project was initiated. At the site, researchers installed three piezometers and a rain gauge to determine if these instruments, along with the surrounding data collection services (climate stations, hydrometric meters, etc.) could determine if the wetland contributes to groundwater recharge. If the pilot project proves to be a successful method in better understanding the wetland of interest’s connection to groundwater recharge, another analysis should be conducted in order to include the newly mapped wetlands in the Gabriola Island Water Region.

6.0 Conclusion

Two methods of interpretation were used to better understand wetland systems within WR7, including preliminary desktop analysis and in-field analysis. These methods were established early in the development of the project and have guided researchers through the mapping and classifying of wetland systems. Based on predictive mapping, five wetland assessments were completed to map and classify systems in WR7. Wetlands were classified based on their soil, hydrology, and vegetation characteristics. One important implication of using predictive mapping to identify wetland sites is the potential lack of accuracy associated with remote sensing, due to coarse imagery. Using predictive mapping, WR7-GI-01 and WR7-GI-02 were classified as fen systems, WR7-GI-03 and WR7-GI-05 were as swamp systems, and WR7-GI-04 was classified as a shallow water system. Moving forward, it should be noted that predictive mapping is only a tool that can be used to guide researchers in identifying potential wetland sites. During in-field ground-truthing of predictive mapping, researchers had the opportunity to analyze each site’s local physiography and hydrogeologic position. Throughout this process, it was observed that many of the wetlands were not consistent with the predictive mapping. The majority of the wetlands were classified as swamp systems and were behaving unique to their location within the water region. As discussed above, it will be very important to move forward with subsurface investigations to better understand existing hydraulic connections at these sites by using data gathered by instrumentation, cross- sectional analysis, and geophysics.

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7.0 References

Bednarski, J.M. (2015). Surficial geology and Pleistocene stratigraphy from Deep Bay to Nanoose Harbour, Vancouver Island, British Columbia. Retrieved from http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R= 295609 doi: 10.4095/295609

Burgess, R. & Adam, D.M. (2016). Groundwater recharge model for Gabriola Island. Retrieved from https://www.rdn.bc.ca/cms/wpattachments/wpID3175atID8124.pdf

Collins, M., Igherighe, C., & Eseka, K. (2013). Analysis of electrical resistivity data for the determination of aquifer depth at Sapele RD in Benin City. Advances in Applied Science Research. 4. 268-276. Retrieved from http://www.imedpub.com/articles/analysis-of-electrical-resistivity-data-for-the- determination-of-aquifer-depth-atsapele-rd-in-benin-city.pdf

Doe, N. (2009). Sandstone & shale – Gabriola’s origins. Retrieved from https://www.nickdoe.ca/pdfs/Webp223c.pdf

Doe, N. (2010). The geology of Gabriola Island’s diatomaceous earth. Retrieved from https://www.nickdoe.ca/pdfs/Webp56c.pdf

England, T. (1989). Late Cretaceous to Paleogene evolution of the Georgia Basin, Southwestern British Columbia. Retrieved from https://research.library.mun.ca/6626/

Freeze, A. & Cherry, J. (1979). Groundwater. Upper Saddle River, NJ: Prentice-Hall.

Geologic Survey of Canada. (1963). Surficial geology, Nanaimo, British Columbia. Retrieved from https://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R =108682

Government of British Columbia. (n.d.). BC wells database. Retrieved from https://a100.gov.bc.ca/pub/wells/public/indexreports.jsp

GW Solutions Inc. (2017). State of our Aquifers: Aquifer 709. Retrieved from https://www.rdn.bc.ca/dms/documents/dwwp-reports/gabriola-water-region/aquifer_709_- _state_of_our_aquifers_report_-_2017.pdf

Hodge, W.S. (1978). A review of groundwater conditions on Gabriola Island. Retrieved from https://www.rdn.bc.ca/dms/documents/dwwp-reports/gabriola-water- region/gabriola_groundwater_conditions_-_1978.pdf

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Islands Trust. (n.d.). Gabriola Island community profile. Retrieved from http://www.islandstrust.bc.ca/media/314027/Gabriola-Final-Profile-Final-Report.pdf

Klassen, J., & Allen, D. M. (2016). Risk of saltwater intrusion in coastal bedrock aquifers: Gulf Islands, BC. Retrieved from http://www.sfu.ca/grrg/SFU%20Final%20Report%20Risk%20of%20SWI%20Framework_2016. pdf

MacKenzie, W. H., & Moran, J.R. (2004). Wetlands of British Columbia: A guide to identification. Victoria, BC. Government of British Columbia, Ministry of Forests Lands and Natural Resource Operations.

Reddy, S. (2017). Geophysics: An overture. Contemporary Research in India. 7. 327-330. Retrieved from: https://www.contemporaryresearchindia.net/Pdf/CRI%20June%202017/60.pdf

Regional District of Nanaimo. (2019a). About the RDN. Retrieved from https://www.rdn.bc.ca/about-the- rdn

Regional District of Nanaimo. (2019b). Watershed 7: Gabriola Island. Retrieved from https://www.rdn.bc.ca/watershed-7-gabriola-island

Regional District of Nanaimo. (2017). State of our aquifers. Retrieved from https://www.rdn.bc.ca/dms/documents/dwwp-reports/gabriola-water-region/aquifer_709_- _state_of_our_aquifers_report_-_2017.pdf

Regional District of Nanaimo. (2012). Rainwater harvesting: Best practices guidebook. Retrieved from http://waterbucket.ca/wp-content/uploads/2012/05/RDN_Rainwater-Harvesting-Guidebook_Oct- 2012.pdf

Regional District of Nanaimo. (2018). GIS interactive mapping [supplemental material]. Retrieved from https://www.rdn.bc.ca/cms.asp?wpID=3541

RSK Group Plc. (n.d.) A reference for geophysical techniques and applications. Retrieved from https://www.geos.ed.ac.uk/~whaler/environmental_geophysics_handbook_lowres.pdf

Southam, T., & Curran, E.A. (1996). The wetlandkeepers handbook: A practical guide to wetland care. Surrey, B.C. Government of British Columbia, Department of Fisheries and Oceans Canada Habitat and Enhancement Branch.

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United States Geological Survey. (2007). Water budgets: Foundations for effective water-resources and environmental management. Retrieved from https://water.usgs.gov/watercensus/AdHocComm/Background/WaterBudgets- FoundationsforEffectiveWater-ResourcesandEnvironmentalManagement.pdf

Waterline Resources Inc. (2013). Water region 1 – Big Qualicum. Retrieved from https://www.rdn.bc.ca/dms/documents/dwwp-reports/big-qualicum-water- region/phase_1_water_budget_study_-_rdn_water_region_1_-_2013.pdf

Yorath, C. (2005). The geology of southern Vancouver Island. Pender Harbour, BC. Harbour Publishing.

Zelt, A., Azaria, A., & Levander, A. (2006). 3D seismic refraction traveltime tomography at a groundwater contamination site. Journal of Geophysics, 71, 68-78. doi: 10.1190/1.2258094

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Appendix A

Table 1: Summary of Wetland Classification and Aquifer Characteristics

Wetland Water Aquifer Wetland Wetland Wetland Aquifer Aquifer Wetland Name Dominant Plant Species Elevation Temperature Water pH Wetland Soils Classification Location Classification Size (ha) Type Confinement (masl) (°C) Code

Moderately strong Hardhack in swamp regions; 49°10'10.4"N decomposed in bog areas, labrador tea and WR7-GI-01 123°50'37.8"W Swamp; bog 5.73 72 n/a n/a organics, almost 709 Bedrock Confined sphagnum spp's unrecognizable

plant structures

Swamp regions contained 49°10'03.7"N hardhack, salmonberry, sword Non-organic silty WR7-GI-02 Swamp 1.03 72 10 5.5 709 Bedrock Confined 123°50'33.5"W fern, and Himalayan loam

blackberry

Hardhack in central swamp, red osier dogwood, salal, 5.5 in Weak decomposed 49°09'54.7"N Swamp; 7 in swamp; 6.5 sedge, skunk cabbage, deer swamp; 5.8 organics near WR7-GI-03 123°51'01.5"W secondary 1.15 86 in shallow 709 Bedrock Confined fern, and bracken fern on the in shallow shallow water; and shallow water water outer edges of the swamp water strong in swamp

Emergent vegetation from the Moderately strong 49°08'39.7"N marsh (sedges, grasses, decomposed WR7-GI-04 123°48'19.7"W Marsh cattail) and Douglas fir, salal, 1.57 80 6 6.2 organics, with clay 709 Bedrock Confined Oregon grape, bracken fern base on outer edges

Hardhack, Douglas fir, 49°08'39.4"N western red cedar, western Very little WR7-GI-05 123°48'20.0"W Swamp 1.75 162 12 5.5 709 Bedrock Confined hemlock, and skunk cabbage decomposition,

mesic organics

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Appendix B

Mapped Aquifers in the Gabriola Island Water Region (GW Solutions Inc., 2017).

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