What You Should Know About Fish Habitat and the Effects of Sediment

Sediment refers to the fine-grained particles that are sometimes transported in water. Sediment often results from work projects in or around water and can harm fish habitat.

Canadian legislation requires that fish habitat be protected in lakes and rivers. By carefully planning your projects and preventing sediment from entering waterbodies, you can help safeguard our fish.

The Working Around Water? series of fact sheets provide information to help you plan your projects with fish habitat protection in mind. This fact sheet provides general information about the effects of sediment on fish and fish habitat. It is not intended to replace the advice of a professional engineer or fish habitat biologist.

Be aware of the Fisheries Act and other legislation

The federal Fisheries Act provides for the protection of fish habitat. Under the Fisheries Act, no one may carry out any work or undertaking that results in the harmful alteration, disruption or destruction of fish habitat, unless authorized by Fisheries and Oceans Canada. The Act also states that no one is permitted to deposit a deleterious (harmful) substance into water containing fish. Violations can result in substantial fines, the risk of imprisonment and a requirement to cover the costs of returning the site to its original state. Other legislation that may also be relevant is outlined in the introductory fact sheet: Working Around Water? What You Should Know About Fish Habitat.

Keep in mind that approval from one government agency does not guarantee that you will be able to obtain approval from another agency. As well as the Fisheries Act, other federal, provincial or municipal agencies may have legal requirements that may affect how to proceed with projects in and around water. Remember you should obtain all approvals before starting work.

Suspended sediment can be harmful

Sediment is the fine-grained particles that are sometimes transported in water. Turbidity refers to the cloudiness of the water because of the sediment suspended in it. Sediment and turbidity can result in a variety of harmful impacts to fish. For example, sediment and turbidity interfere with feeding for visual feeders such as trout and bass. Some of the negative effects of turbid water are:

• abrasion of gill membranes.
• impairment of feeding.
• fatal impacts to small aquatic animals that are food for fish.

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Deposited Sediment Can Be Harmful

Suspended sediment results in turbid water that can harm fish. Deposited sediment can also be harmful to fish habitat.
Some of the harmful impacts of sediment deposits are:

• The small spaces between gravel particles become clogged, preventing the free flow of oxygenated water and the removal of waste products from developing eggs deposited in the gravels. This often suffocates the eggs and results in their death. In fact, it may even make gravel beds unsuitable for the future incubation of eggs.
• The habitat of bottom-dwelling organisms, such as crayfish and insects, is destroyed. Fish rely on these organisms for food.
• The sheltered areas between boulders and gravel particles are eliminated. Young fish need these areas to survive.
  

Figure 1: Deposited sediment on gravel stream bottom

Figure 2: Clean gravel stream bottom

Avoid Introducing Sediment into Lakes and Rivers

Since sediment and turbidity may create a variety of harmful impacts to fish and fish habitat, it is important to avoid the introduction of sediment into our water by planning and designing work projects with care and carrying them out with attention to safeguarding the environment.

There are a variety of ways sediment can be introduced into a waterbody.

• Disturbance of vegetation or other stabilizing soil cover often results in erosion of the exposed soils. For example, the building of improper stream crossings or clearing trees and vegetation to a stream bank may result in soil erosion.
• Fine particles can also be released from some mechanical processes such as mining or rock crushing.

For most construction or development projects that cause the release of sediment, there are effective methods for removing it from site water and preventing it from entering streams or lakes.

If you are planning a project in or near water, you must use environmentally friendly practices to avoid the introduction of sediment into waterbodies. Be sure to apply for all necessary approvals and permits before undertaking any work around water.

This Fact Sheet does not constitute Fisheries and Oceans Canada approval; other mitigation measures may be required. It is your responsibility to contact all other appropriate regulatory agencies.

For more information on how to work around water in an environmentally friendly manner, or to obtain copies of other fact sheets in this series, contact your local Manitoba Conservation District Office or:

Fisheries and Oceans Canada - Habitat Management
501 University Crescent
Winnipeg, Manitoba R3T 2N6
Phone (204) 983-5163; Fax (204) 984-2402

Federal and provincial offices are listed in your phone book under Government of Canada and Government of Manitoba.

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