Course:EOSC270/2023/Group 3: Human Impacts on the Squamish Estuary

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History of the Squamish Estuary

Figure 1. A bird's eye view of the Squamish Estuary from the The Chief hike in Squamish.

What is the Squamish Estuary?

The Squamish Estuary is where the tide of the Pacific Ocean meets the freshwater of the Squamish, Mamquam and Stawamus rivers.[1] Aside from their beauty, the Squamish estuary has been identified as an essential ecosystem due to its high biodiversity, cattails and shrubs that filter the water providing a cleaner marine environment and protecting coastal regions with their absorption-like abilities during rainy seasons[2]. The interaction between the waters of the rivers and seas, as well as their varying salinities and temperatures, introduces a current that aids the facilitation of nutrients, making estuaries a primary area for production. Marine life in this region ranges from invertebrates such as ghost shrimp and clams to coho salmon, flounders and seals. This biodiversity hotspot is likely a result of the early life productivity of the region. Aside from the Estuary's rich marine life, it also accommodates impressive land life, with deer, bears, cougars and coyotes thriving in the ecosystem.

What Happened to the Squamish Estuary?

In the 1970s, BC Rail dredged a 5km long manufactured spit through the middle of the Squamish Estuary, causing massive disruptions in the ecosystem and cutting off a source of its freshwater, consequently drying a region of its waters[2]. Spits are sand deposits that block water flowing in an area and elongate land pieces stretching out into the ocean[5]. With help from this wind, this is often a slow and naturally occurring phenomenon, but its impact is very harsh on the environment when manufactured. Along with altering the natural path of merging water bodies, the railroad company also cut down old-growth trees to create space. The Federal government soon denied the company's hope of building a coal port, resulting in the company abandoning the area. In rejecting the project, the company left the spit in place, and no attempt was made to restore the ecosystem for over 30 years.

Figure 2. An image depicting the before and after (years of 1969 and 1973) of the dredging of the Squamish Estuary, as well as the restoration effects from their attempt in 2016

Another adversity that the complex ecosystem faces is balancing the needs of our ever-developing human population with respect for the environment and restoring the harm caused in the past. Squamish is an attractive home to many due to its outdoor access and adventure-seeking activities. However, with its rising population comes an increasing need to develop the land around the town to keep up with human needs. [3]The spit has grown into a local hotspot for windsurfing. In particular, the Mamquam river region, located closest to the town, is heavily exploited by humans and now serves as an industrialized logging area disrupting the ecological cycle of this area[4]. One way to create more space around the town is by draining the estuary for housing and development. Due to both the spit and development draining, the Squamish Estuary area is shrinking, posing a significant threat to the ecosystem.

Figure 3. An image of Fritillaria camschatcensis , more commonly known as the chocolate lily

The pervasiveness of this issue is severe and needs to be explored further. For example, the Fritillaria camschatcensis, more commonly known as the chocolate lily or Lhásem, to the people of the Squamish First Nations, whose flowers are valuable food sources and hold immense cultural importance. The damage done to the Squamish Estuary has stunted the growth of these plants, which consequently stripped away a food source from the Squamish First Nations[5]. Such disturbances cause a ripple throughout the region, and the accumulation of human actions over time has potentially threatened the entire ecosystem. However, estuaries are resilient, and though the Squamish estuary has dealt with many adversities, it still serves as an essential ecosystem in the area.

How Does this Problem Impact the Squamish Estuary Ecosystem?

How Did Dredging Alter the Estuary?

During the 1970’s, 12.0 hectares of the marsh in the west delta was destroyed due to river channelization, where the river channel was straightened to drain water more efficiently from the growing community of Squamish and to support future port development[6]. Dredging, which is the processes of removing sediment from the bottom of a river, occurred in the central delta which led to an additional 14.2 hectares being lost, and a stockpile was created to hold the sand that was removed[6]. Along with the negative impacts of dredging, the creation of the spit also degraded the ecosystem by changing the river currents throughout the estuary, leading to changes in salinity levels and depositing rates of sediment[7]. The spit slowed water movement in the estuary, which reduced crucial habitats such as tidal marshes due to less sediments being deposited. This also decreased the estuary’s natural buffer that would otherwise help mitigate sea level rise, leading to even worse flooding.

The Squamish Estuary is Crucial Habitat for Juvenile Salmon

The industrialization of Squamish and the dredging of the estuary drastically impacted the health of this ecosystem. The Squamish estuary used to flow into Howe Sound through two main channels, but the east arm was blocked by the construction of the spit, preventing direct freshwater flow[6]. The estuary was an important habitat for juvenile salmon, as they would spend three to four months protected in this area, growing and preparing for the open ocean[8]. However, the creation of the spit altered the water flow in this ecosystem, sending these vulnerable salmon out to sea, bypassing the safety of the estuary, before they were mature[1]. This decreased their chances of survival and contributed to a reduction in population size. The Chinook salmon population size exemplified this impact as it reduced to less than 500 in the 1980’s, when the population size was previously 17,000 between 1962 and 1972[1]. After decades of restoration, the Chinook salmon population has increased to 5,000 today.

Figure 4. The Squamish Estuary supports a large eagle population who benefit from the annual Squamish River salmon spawn

What Other Species Inhabit the Estuary?

The Squamish estuary provides habitat for seals, coyotes, beavers, river otters, great blue heron, and black-tailed deer[2]. It is an important resting site for migrating birds such as swans, geese, and ducks, and this ecosystem supports a large population of eagles (Figure 4) who benefit from the Squamish River salmon spawn in the fall[7]. As these species are all connected through the food chain, the depletion of salmon and other secondary consumers altered the delicate equilibrium of the ecosystem and affected the population health of their predators.

Why is Restoring the Estuary Important?

To Restore and Maintain its Biodiversity

The Squamish Estuary is vital for the survival of a wide diversity of both marine and land animals from the transport of food and nutrients to providing habitats for various species[2]. This aspect is one of the main reasons why the Squamish Estuary should be restored quickly as by doing so, the habitats and food supply of many organisms such as salmon and black bears can be replenished, and therefore, slowly restore the equilibrium within the ecosystem.

To Combat Climate Change

The estuary also plays a part in reducing the levels of greenhouse gases. Estuaries are known to be huge carbon sinks[9]. These sinks are capable of absorbing and removing atmospheric carbon. Present in the estuary are primary producers such as seagrass. They utilize and reduce carbon to produce oxygen, furthering alleviating atmospheric carbon levels and combating climate change[9]. Salt marshes are also present in the estuary and are responsible for alleviating carbon as well[10]. It was also found that in a healthy estuary (i.e., an estuary that has not been disturbed and heavily modified), a combination of salt marshes and seagrass beds can sequester more carbon than terrestrial ecosystems suchs forests[10]. This once again showcases the vitality and importance of a healthy, restored Squamish Estuary for our environment.

Figure 5. A poster summarizing the importance of estuaries to both land and marine organisms and the Earth's climate[11]

Economic Benefits

Aside from environmental reasons, the estuary also provides economic benefits through their flood mitigation and water filtration. It is said that the Squamish Estuary is responsible for $12.6 million worth of services and goods every year[1]. A few examples of these services and goods are: a constant supply of good drinking water and air quality , dilution of pollutants and a stable food supply for business and/or survival[12].

Factors to Consider Prior to Restoration

Figure 6. ‘Spit Island’, now only boat accessible unless there’s a very low tide, used as a launch site for wind sports[13]

The Right holders and Stakeholders of the Squamish Estuary

The Squamish First Nation's wishes entail respect for the land and organisms within it; the Secwepemc people traditionally follow the path of salmon upstream, with their fishing villages alongside, given the assurance of a constant food source, and they believe that salmon bestow wisdom upon these people when treated respectfully [14]. However, artificially altering their migration paths therefore interferes with such traditions, which have played an important role in these communities for “over a thousand years” according to Elder Ralph Philips of Xatśūll First Nation. Thus, this community wants full restoration of this ecosystem to allow juveniles to complete their journey through the estuary.

But, Squamish has an increasing population, leading to increased demands on habitats for outdoor recreation activities. For example, the spit provides a world-class location for kite surfers to launch, and there were almost 3000 signatures petitioning against its removal as a restoration attempt [1]. However, leaving an island at the end of where the spit used to be (Figure 6) was offered as a compromise, and despite initial criticisms demanding road access, the Windsports Society purchased a boat and found this a very viable alternative to the original spit, whilst maintaining respect for the Squamish Nations wishes[1].

Restore the Shore Initiative

Figure 7. Map of the estuary[15]

Additionally, First Nations concerns and expectations are parallel with those of the ‘Restore the Shore’ group (compiled of the Squamish Nation, Squamish River Watershed Society, and Fisheries and Oceans Canada) who seek to revert this ecosystem to its former glory, and thus protect salmon populations [1]. Moreover, Simenstad et al. [16] found that juveniles remain in Washington’s estuaries for up to 6 months, given these waters act as a prolific food source, facilitating growth, for example neritic zooplankton are in higher concentrations than in ocean waters given the stable water column. Chum salmon were found to have their highest growth rate across their life history at up to 10.1% body weight/day whilst in estuaries[16]. These habitats also help avoid predation, with eelgrass providing camouflage, exacerbated by the highly turbid estuarine waters. These juveniles also undergo the smolt phase here, cued by increasing salinity in these waters; altering their physiology to increase their survival chances in the ocean [17]. Additionally, sampling of the Skeena River estuary revealed high species richness, with six juvenile salmon species in the estuary, proving the importance of these habitats to maintaining high population diversity [18]. And this is subsequently vital to ensure genetic diversity remains high, meaning the species are able to adapt to changes (e.g. increasing temperatures), furthering survival chances.

Therefore, this group advocates the cruciality of estuarine waters for juveniles to properly progress through their life history stages, and ensure maximal survival chances in the open ocean.

However, companies located in the area, such as Squamish Terminals, rely on the current sediment composition to move their vessels when importing and exporting cargo. Thus, removal of the spit is likely to cause increased build-up of sediment near their ports, affecting transportation (Figure 7). Therefore, they are likely to object to any restorative procedures as it could potentially put them out of business.

Therefore, there are evidently multiple groups whose viewpoints must each be consulted and considered when taking on the project of reversing the damage to this crucial ecosystem, and compromises must be made to placate all parties to achieve a sustainable solution.

What is Being Done to Solve this Problem?

Past Projects

From 1982-1999, Management plans including the Squamish Estuary Management Plan were starting to be published and certain groups with the help of the Provincial Government of BC started restoration projects. Within the next 16 years, restorations including:

  • Restoring salt marsh, eelgrass beds, tidal channels, and training berms of up to 28 football fields long (15 hectares)
  • Installing culverts and trash racks along berms
  • 25,000 m2 of vegetation and channel habitat restoration
  • Bridges for pedestrians and the start of a launch pad for water recreation[19]
  • Between 1,200 and 2,000 Native Riparian trees, shrubs, and sedge plugs planted with sludge mush proving to be a success
  • Building of public access resources including kiosks, trail signs, and a 1,200m trail along the estuary
  • Continuous monitoring of sites in order to make sure the habitats and communities of plants and soil are being successful[20]
Figure 8. The management timeline of the Restore The Shore Society

In the spring of 2012, with successful plantation plans in other areas of Squamish the prior years, 1500 eelgrass shoots were planted by the help of many volunteers and the BC Wildlife Federation [21]. More recent events, around 2021 to 2022, 300 m of the spit become deconstructed with future plans being to remove 550 more later that year. The funds for this dismantling were provided by the Coastal Restoration Fund, Pacific Salmon Foundation, Habitat Conservation Trust Fund and the Fish and Wildlife Compensation Program[1].

The Blue Carbon Project was created to restore the damages and decrease the new atmospheric carbons caused by the disruption to the Squamish Estuary. As stated by the Squamish River Watershed Society, Phase 1 was to collect data on the vegetation and soil, create funding and partnerships, and develop policies before moving forward. The North American Partnership for Environmental Community Action (NAPECA) grant provided funding for the project as well as partnering up with The Project Watershed and being approved by the Federal Environmental Minister. Phase 2 included photo monitoring, data collection, and field work from many volunteers and scientists[22].

Future Plans

There are still limitations to the estuary’s habitable functions and fish access due to the training berm and spur line. The Juvenile Chinook, for example, are experiencing a decrease in fitness and survival due to the salmon being sent through the training berm too early in their life stage. Similarly, the berm and spur line are negatively affecting the brackish mixing of the estuary’s water which decreases the needed functions of the habitat. The Squamish Nation joined with the provincial government created a three phase plan that includes upgrading the culverts that are already in place to increase the well-being of the fish, reconnecting the low parts of the estuary by improving the lower section of the berm, and including a flow control device to the rail spur[23] In addition, following the removal of the 300m berm in 2022, the split road will undergo a complete reconstruction with space left for the water recreational sports [19].


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "Inside a 50-year Journey to Reopen "lungs" of the Squamish River". The Narwhal.
  2. 2.0 2.1 2.2 2.3 "About the Estuary". Squamish Watershed. 2016.
  3. "Let's bring back the health of the Squamish estuary through restoration and reconciliation".
  4. "What is the deal with that Squamish log sort?".
  5. "Finding our roots".
  6. 6.0 6.1 6.2 Levings, C.D. (1980). "Consequences of training walls and jetties for aquatic habitats at two British Columbia estuaries". Coastal Engineering. 4: 111–136.
  7. 7.0 7.1 Hessing-Lewis, Margot (2005). "Assessing The Potential For Eelgrass Restoration In The Squamish Estuary, British Columbia". Library and Archives Canada.
  8. Hodgson, Emma (2019). "Changing estuaries and impacts on juvenile salmon: A systematic review". Global Change Biology. 26: 1986–2001.
  9. 9.0 9.1 Poppe, Katrina L.; Rybczyk, John M. (May 2018). "Carbon Sequestration in a Pacific Northwest Eelgrass (Zostera marina) Meadow". Northwest Science. doi: Check |doi= value (help).
  10. 10.0 10.1 Spooner, Angela M. "Blue carbon sequestration potential in Zostera marina eelgrass beds of the K'ómoks Estuary, British Columbia". Royal Roads University.
  11. "OceanWatch - HoweSoundReport" (PDF).
  12. Culberson, Steven D. (July 2021). "Estuaries, Human Beings, and the Future". Frontiers for Young Minds. doi:10.3389/frym.2021.611371.
  13. Explore Squamish. "Wind & Kite Surfing".
  14. Indigenous Tourism British Columbia (2019). "Living Legends: The Teachings of the Salmon".
  15. Squamish Trails Society. "Estuary Trails".
  16. 16.0 16.1 Simenstad, Charles; Fresh, Kurt; Salo, Ernest (1982). "The Role of the Puget Sound and Washington Coastal Estuaries in the Life History of Pacific Salmon: an Unappreciated Function". Estuarine Comparisons: 343–364.
  17. Samantha, Hodgson; Wilson, Samantha; Jonathan, Moore (2020). "Changing estuaries and impacts on juvenile salmon: A systematic review". Global Change Biology. 26 (4): 1986–2001.
  18. Carr-Harris, Charmaine; Gottesfeld, Allen; Moore, Jonathan (2015). "Juvenile Salmon Usage of the Skeena River Estuary". PLOS ONE. 10 (3).
  19. 19.0 19.1 Restore The Shore (2021). "History". Restore The Shore.
  20. Squamish River Watershed Society (2016). "West Wind/West Barr Restoration". Squamish River Watershed Society.
  21. Moscoso, A.D. (2012). "Eelgrass and estuary:1,500 eelgrass plants added to Squamish estuary". BCWF Bog Blog.
  22. Squamish River Watershed Society (2026). "Blue Carbon Project". Squamish Watershed Society. Check date values in: |date= (help)
  23. Squamish River Watershed Society (2016). "Training Berm Upgrades (CERP)". Squamish River Watershed Society.