Preventing Impacts to Important Aquatic Habitats
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Preventing Impacts to Important Aquatic Habitats 
Preventing Impacts - Bull Kelp (DNR) 

Preventing Impacts to Important Aquatic Habitats 

Washington’s history and culture are linked to our relationship with our waters — such as Puget Sound, the Columbia River, Lake Chelan and many other lakes and rivers. These water bodies are managed by DNR to provide transportation, commerce, food, drinking water, and places to sail, swim and fish. As Washingtonians, we depend on our waters and we need them to be healthy.

Perhaps the most important part of any water body is the band of habitat between dryland and the deep water known as the nearshore environment.

The nearshore supports a unique community of plants, algae and animals that are the foundation of life for both aquatic and terrestrial wildlife. Aquatic vegetation is the cornerstone of these communities - kelp, seaweed, and aquatic grasses, can only grow where the water is shallow or clear enough for sunlight to reach them.

Why we should care 
If the aquatic ecosystem were a building, the aquatic plants would be the foundation. For a multitude of species, nearshore plants provide food, shelter, refuge from predators, and a safe place to grow. The plants create oxygen, recycle nutrients, and put roots down to hold the sediments in place.

Unfortunately, this critical and sensitive habitat also is the same area where most human activities occur — docks, marinas, mooring buoys, boat ramps, and shellfish farms — that are almost always located in the nearshore. These structures and activities can seriously affect nearshore communities by:

  • Blocking sunlight that plants and algae need to grow
  • Disrupting the movement of water and sediment along the shore that provides nourishment, places to spawn or take root in, and shelters clams and insects
  • Degrading the quality of the water through the release of human waste and contaminants
  • Crushing the delicate habitat when floating structures drag across or ‘ground out’
  • Creating noise that may cause species to avoid the area or abandon their nests

Impacts that harm nearshore communities - and DNR stewardship measures to reduce them

Shade
Water Movement, Waves, and Impacts to Sediment
Crushing of Sediment and Habitat
Contamination
Noise

Preventing Impacts - shade (H. Shipman)Shade
Structures built over the water can cast large deep shadows that can kill aquatic vegetation by depriving them of sunlight, and can create a migration barrier for juvenile salmon and other fish. When the vegetation is lost, there is less food and fewer places to shelter for fish, and erosion increases. Juvenile salmon, rockfish and other fish migrate along the shore, using the vegetation for shelter from their predators. When young salmon come to large deep shadows with long straight lines they often swim around them into deeper water. This uses more energy and leaves them more vulnerable to the predators that live in the deeper water.
Swimming through the shade also is dangerous because it is harder to see predators. A number of measures can reduce these impacts:

  • Place structures in deeper water where they will not shade aquatic vegetation.
  • Remove unnecessary structures.
  • Modify existing structures in the nearshore so that sunlight can pass through them.
  • Locate new structures away from aquatic vegetation.

Preventing Impacts - Water movement, waves (C. Cloen)Water Movement, Waves, And Impacts To Sediments 
Along the nearshore of our marine and fresh waters, some built structures, such as ‘armored’ shorelines, and human activities change the actions of waves and currents, altering the way they move sediment and materials through the water. Because many shallow-water communities rely on the movement of sediment to replenish nutrients, bring in food and carry away wastes, disrupting wave and current energy can lead to increased erosion or buildup of wastes. Boat wakes also can create unnaturally large or frequent waves on the shore that can erode the sediments near the shore, weakening or killing the native plant communities.
Structures like piers and pilings — if there are too many of them — can slow waves or currents reducing or stopping the natural flows of sediment along the shore. In shallow water, boats also can threaten aquatic plants when their props scour the bottom churning up the sediments, smothering the plants or removing sediment from around their roots. Prop scour also can destroy aquatic plants by chopping them up.

A number of measures can reduce these impacts:

  • Design new overwater structures and facilities so that shoreline armoring is not needed.
  • Replace existing hard armoring with a system that reduces impacts.
  • Post ‘no wake signs’ to direct boaters to reduce wave heights along the shore.
  • Design structures so they minimize obstruction of currents and alteration or sediment transport to prevent stagnation and the buildup of waste.
  • Locate new facilities further from shore in deeper water.
  • Minimize noise during native species’ breeding or migration times.
  • Locate structures and activities away from native aquatic vegetation or other sensitive areas.
  • Wash gravel or shell to be used for aquaculture beds in an upland location so the wash water doesn’t enter the waterbody.
  • Observe work windows within nearshore areas to minimize impacts to native species at vulnerable times in their lives.

Preventing Impacts - Crushing the Sediment (C. Piening)Crushing The Sediment Habitat 
During periods of low water, whether in rivers, lake or marine waters, some floating structures can crush the vegetation and animals that live beneath them. For example, in shallow marine waters, this can be caused when floats, rafts and mooring buoys repeatedly strike the bottom as they are lifted and lowered by the tide twice a day. Vehicles driven in shallow water or tidelands also can destroy nearshore communities. When the sediments are compacted, they may not be able to support aquatic vegetation and the area becomes inhospitable to all but a few species.

These impacts can be avoided by the following measures:

  • Place structures and activities in deeper water beyond where aquatic vegetation can grow, or design them so they cannot “ground out” or strike the floor of the waterbody.
  • Use embedded anchors and midline floats to minimize dragging of chains and ropes.
  • Locate boat landings in areas where boats and barges do not run aground, and propellers do not disturb the sediments or aquatic vegetation.
  • Wash gravel or shell to be used for aquaculture beds in an upland location where wash water cannot enter the waterbody.
  • Observe work windows within nearshore areas to minimize impacts to native species at vulnerable times in their lives. Limit vehicular or foot traffic in shallow water and intertidal areas to those times needed for operations, and to minimize destruction of a larger area, use designated routes.

Preventing Impacts - Contamination (DNR)Contamination
All operations over or near the water run the risk of releasing contaminants into the water. These chemicals, waste products, and even excess nutrients often can kill organisms directly, or can build up in the ecosystem over time causing chronic health problems. While these spills often are unintentional, the results are serious. The toxics are picked up by rainwater and deposited into nearby waters where they can pollute the broader aquatic environment.



The following measures can reduce these impacts:

  • Design and locate facilities so that the water can freely flow through to prevent stagnation and the buildup of waste and sediment.
  • Use protective measures to prevent discharges of contaminants to water by:
    • Limiting in-water repair, and move the refinishing of boats out of water or to decks and superstructures.
    • Design and locate facilities so that the water can freely flow through to prevent stagnation and the buildup of waste and sediment.
    • Use protective measures to prevent discharges of contaminants to water by:
    • Prohibit in-water hull scraping or any process underwater that removes paint from the boat hull.
    • Prohibit refinishing work from on boats and temporary floats unless permitted by a National Pollution Discharge Elimination System (NPDES) permit.  
    • Use tarps to prevent dust, drips, and spills from entering the water. 
  • Provide sewage disposal facilities at marinas.
  • Prevent contaminated runoff from entering the water.
  • Keep sites clean of litter.
  • Properly dispose of waste and contaminants.
  • Use best management practices to exclude or eliminate pests, so pesticides are unnecessary.
  • Wash gravel or shell to be used for aquaculture beds in an upland location where the wash water cannot enter the waterbody.
  • For log booming and storage activities, implement practices that prevent bark from rubbing off of the logs in the water.

Preventing Impacts - log loader noise (C. Piening)Noise
The noise caused by operations can traumatize fish, birds, amphibians, and orca causing them to leave the area or abandon their nests. Their movement away from the site also may lead to a loss of foraging opportunities and can lead to weight loss due to the increased movement and loss of food.




The following measures can reduce these impacts:

  • Locate new facilities in deeper water away from the nearshore environment, and where possible, move existing facilities into deeper water away from the nearshore.
  • Observe species work windows to minimize noise impacts at vulnerable times in their lives.
  • Limit vehicular or foot traffic in shallow water and intertidal areas to that needed for operations and using designated routes.

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For General Questions and Information:
Washington State Department of Natural Resources
360-902-1100
ard@dnr.wa.gov

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