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Gulf Islands National Park Reserve of Canada

Restoring the Habitat of Lyall Creek

Habitat | The Habitat of Lyall Creek | The Creek's Climate | Self-Sustainability | Habitat Degradation | Restoring the Habitat of Lyall Creek | Riparian Zones | Restoring Lyall Creek's Riparian Zone | The Riparian Species of Lyall Creek | What's Next for Lyall Creek


Lyall Creek provides habitat for a vast number of species.

Over time, species of plants and animals living in the same area evolve very complex systems amongst themselves and with their physical surroundings. The elements and processes that support a species in terms of its life requisites (food supply, protection from predators and environmental stresses and reproduction) are called habitats .

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The Habitats of Lyall Creek

The creek experiences many changes throughout the course of the year. Following heavy rainfalls in the fall, the channel is a torrent of muddy water, at times overflowing the banks and carrying debris and nutrients far into the woods. Waterfalls cascade over maidenhair ferns and deafen the sound of the creek below.

The Lyall Creek Habitat The Lyall Creek habitat
© J. Mercer, Parks Canada / 2005

This powerful system quiets down to a mere trickle during dry summer months. At it's driest, standing water is visible only a third of the way upstream, seeping out of sight underground and standing still in the wetlands that act as sponges storing and releasing water to maintain the system until the next big rains.

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The Creek's Climate

Surrounded by high ridges on either side, the creek creates a climate all it's own. On the ridgetops it can be hot and dry, while in the valley bottom conditions tend to be cool and humid. Lichens and mosses thrive in this moist environment, as do the nutrient loving swordfern, nitrogen fixing alders and majestic red-cedar and big leaf maple.

Returning salmon contribute by transferring marine derived nutrients to the stream itself and to the adjacent riparian forest, enriching the surrounding vegetation and supporting organisms that feed on them.

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The Lyall Creek Habitat, horsetail The Lyall Creek habitat, common horsetail
© T. Rutherford and T. Michelski, Parks Canada / 2005

When habitats are healthy, they are self-sustainable . None of the species in the habitat need any outside help to survive. However, when even a small feature of the habitat changes beyond the range of natural variation, all the species that share in the habitat's cycle may be affected.

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Habitat Degradation

Habitat degradation is a major factor in causing a species population to decrease, and may eventually lead to endangerment, or even extirpation (local extinction). Habitat degradation might happen when a species that didn't evolve with the ones that are native to the habitat is introduced by human intervention. Habitat degradation might also happen when human activity causes disturbance or changes in or around the habitat.

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Restoring the Habitat of Lyall Creek

Habitat Restoration is the process of returning habitat in a given area to some degree of its former self. While it is rarely possible or desirable to restore the land to some historic condition, the rehabilitation process usually attempts to return the system and its processes, structures and functions to a more natural balance and a state of self-sustainability. The objective of this restoration work was to improve the habitat features of the creek so that the creek would then be able to heal itself by finding a more "natural balance" under it's own powers. The two main components of the restoration project are the following:

1: Salmon Re-introduction

Salmon have a complex reproductive process that requires two habitats— fresh water streams and lakes, and the ocean. Salmon are born in the stream, swim downstream to the ocean and when they are ready, they return to their place of birth to spawn and die. Returning the salmon population to its healthy size helps restore the habitat as a whole, as salmon put valuable marine-derived nutrients into the forest. In Lyall Creek, habitat alteration resulted in the loss of chum populations and the depletion of coho salmon and cutthroat trout.With support from Fisheries and Oceans Canada, volunteers began to incubate chum eggs in Lyall Creek and release the fry into the creek. Chum salmon are now returning to the stream exceeding 400 fish in 2001. This project continues to this day—each spring thousands of chum fry are released into the Lyal Creek system.

2: Stream Restoration

Picture of the new Lyall Creek's culvert The new Lyall Creek culvert
© T. Golumbia, Parks Canada / 2005

The second issue that was addressed as part of the Lyall Creek restoration effort was the replacement of the culvert. A culvert is a covered structure that allows water to pass under a road, railroad or other obstruction. The old culvert at the crossing of East Point Road was simply too high above stream level for chum salmon to continue upstream to their spawning ground so volunteers passed the live fish by hand across the road.
In September 2003, the culvert at the crossing of East Point Road was replaced with one capable of withstanding a 150-year flood event.
The new culvert returns more natural water flows and allows fish to swim upstream. The new culvert also restores natural sediment transport.

Sediment is made of soil and rock or mineral fragments carried along by the current. In streams and rivers, as the water slows, sediment is deposited, heavier particles (like gravel) first and lighter (sand and silit) particles further downstream.

Eventually, finer sediment creates the river's estuary . In Lyall Creek the old culvert slowed water flow above it so finer sediment would accumulate upstream. As water accelerated below the culvert it scoured sediment in the stream bed, changing the natural gradient and flow characteristics of the creek, as well as the chemistry of the water. Salmon create redds— depressions in gravel stream bottoms where they lay their eggs. The large particle sediment protects the eggs while allowing oxygen-rich waters to flow through and nourish them.  For this reason restoring the natural sediment flow to Lyall Creek is crucial to the salmon's existence.

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Riparian Zones

Riparian areas are the transitional zones between the land and the water. It is these areas along watercourses that are prone to flooding or are significantly influenced by the adjacent aquatic systems.

Riparian ecosystems are vital to the health of all other aquatic ecosystems. They filter out pollutants from land runoff and prevent erosion. They also supply shelter and food for many aquatic animals. They even provide shade, which helps to regulate the temperature of the stream.

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Restoring Lyall Creek's Riparian Zone

In September of 2005, in-stream restoration works for the Lyall Creek habitat restoration effort were completed. Root wads, logs and large boulders were anchored into the banks of the creek upstream of the culvert to create structures which function to increase the complexity of the water course and improve habitat for all aquatic and riparian species.

Before and after pictures of a section of the Lyall Creek riparian zone. The photograph on the left shows the riparian zone as it was before the culvert was replaced, while the photograph on the right shows the riparian zone after. Before and after pictures of a section of the Lyall Creek riparian zone. The photograph on the left shows the riparian zone as it was before the culvert was replaced, while the photograph on the right shows the riparian zone after.
© T. Golumbia, Parks Canada / 2005

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The Riparian Species of Lyall Creek
The red-legged frog The red-legged frog
© K. Ovaska, Parks Canada / 2005

Amphibian and reptile surveys in riparian and wetland habitats undertaken in Gulf Islands National Park Reserve in 2004 confirm the presence of four native species of amphibians in the Lyall Creek watershed: the Long-toed salamander, Rough-skinned Newt, Red-legged Frog and Pacific Treefrog.

The Red-legged frog is particularly abundant along the main channel. It is listed as "special concern" by the Committee on the Status of Endangered Species in Canada and is on the provincial blue list of species at risk.

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What's Next for Lyall Creek

The work that is being done in Lyall Creek is far from over. In partnership with the residents and with Fishery and Oceans Canada, Parks Canada is still working to re-establish off-channel habitat and wetland areas, to remove all artificial in-stream structures and to restore native riparian vegetation.

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Background of Lyall Creek
Anatomy of a Creek
Baseline Inventory and Monitoring
Salmon Species