Natural Systems

This section contains brief and general descriptions of the natural geographic systems around which the shoreline management program is designed. The intent of this section is to define those natural systems to which the Shoreline Management Act applies, to highlight some of the features of those systems which are susceptible to damage from human activity, and to provide a basis for the use activity policies and regulations as well as the shoreline environment designations and management policies contained in this Shoreline Master Program.

Additional Information

The information found in this section was derived mainly from the Department of Ecology's section on The Natural System in the Final Guidelines, Shoreline Management Act, 1971, (WAC 173-16-050). It was intended that this section should provide criteria to local governments in the development of their master programs.

Marine Beaches

Beaches are relatively level land areas which are contiguous with the water and are directly affected by marine waters even to the point of origination. The most common types of beaches in Washington marine waters are sandy and rocky.

Sandy Beaches

Waves, wind, tide, and geological material are the principal factors involved in the formation of beaches. The beach material can usually be traced to one of four possible sources: the cliffs behind the beach; from the land via rivers; offshore wind; and finally from long shore-drifting of material. Long shore-drifting material must have been derived initially from the first three sources. Most beach material in Puget Sound is eroded from the adjacent bluffs composed of glacial till.

The effect of wave action on the movement and deposition of beach material varies depending upon the size of the material. Hence, in most cases, beaches composed of different sized material are usually characterized by different slopes and profiles. The entire process of beach formation is a dynamic process resulting from the effect of wave action on material transport and deposition. Initially, wave action will establish currents which transport and deposit material in various patterns. However, once a particular beach form and profile is established, it begins to modify the effects of waves thus altering the initial patterns of material transport and deposition. Hence, in building beach structures such as groins, bulkheads, or jetties, it is particularly important to recognize that subsequent changes in wave and current patterns will result in a series of changes in beach formation over time (see Use Activity Policies and Regulations).

Beach Formation

In the process of beach formation, sand particles are transported up the beach by breaking waves that wash onto the beach in a diagonal direction and retreat in a vertical direction. At the same time, long shore currents are created in the submerged intertidal area by the force of diagonally approaching waves. Beach material suspended by the force of the breaking waves is transported in one direction or another by the long shore current. Long shore-drifting of material often results in the net transportation of beach material in one direction causing the loss of material in some areas and gains in others.

The profile of a beach at any time will be determined by the wave conditions during the preceding period. Severe storms will erode or scour much material away from the beaches due to the force of retreating waves. During calm weather, however, the waves will constructively move material back onto the beach. This destructive and constructive action, called cut and fill, is evidenced by the presence of beach ridges or berms. New ridges are built up in front of those that survive storm conditions as sand is supplied to the beach in succeeding phases of calmer weather. In time, the more stable landward ridges are colonized by successional stages of vegetation. The vegetation stabilizes the ridges, protects them from erosion, and promotes the development of soil.

Rocky Beaches

Rocky beaches, composed of cobbles, boulders, and/or exposed bedrock are usually steeper and more stable than sandy shores. Coarse material is very permeable which allows attacking waves to sink into the beach causing the backwash to be reduced correspondingly. On sandy shores a strong backwash distributes sand more evenly, thus creating a flatter slope.

On rocky shores a zonal pattern in the distribution of plants and animals is more evident than on muddy or sandy shores. The upper beach zone is frequently very dry, limiting inhabitants to species which can tolerate a dry environment.

Intertidal Zone

The intertidal zone is a narrow area between mean low tide and mean high tide that experiences uninterrupted covering and uncovering by tidal action. One of the major characteristics of this zone is the occurrence of tidal pools which harbor separate communities which can be considered subzones within the intertidal zone.

Subtidal Zone

The subtidal zone is characterized by less stressful tidal influences but is subject to the forces of waves and currents which affect the distribution and kinds of organisms in this zone.

Dunes are mounds or hills of sand which have been heaped up by wind action. Typically, dunes exhibit four distinct features, as listed below:

  • Primary Dunes - The first system of dunes shoreward of the water, having little or no vegetation, which are intolerant of unnatural disturbances.
  • Secondary Dunes - The second system of dunes shoreward from the water, with some vegetative cover.
  • Back Dunes - The system of dunes behind the secondary dunes, generally having vegetation and some top soil, and being more tolerant of development than the primary and secondary systems.
  • Troughs - The valleys between the dune systems.

The Importance of Dunes

Dunes are a natural levee and a final protection line against the sea. The destructive leveling of, or interference with the primary dune system (such as cutting through the dunes for access) can endanger upland areas by subjecting them to flooding from heavy wave action during severe storms and destroy a distinct and disappearing natural feature. Removal of sand from the beach and shore in dune areas starves dunes of their natural supply of sand and may cause their destruction from lack of sand. Appropriate vegetation can and should be encouraged throughout the entire system for stabilization. Check out the Use Activity Policies and Regulations for more information.

An estuary is that portion of a coastal stream influenced by the tide of the marine waters into which it flows and within which the sea water is measurably diluted with freshwater derived from land drainage.

Zones of Ecological Transition

Estuaries are zones of ecological transition between fresh and saltwater. The coastal brackish water areas are rich in aquatic life, some species of which are important food organisms for anadromous fish species which use these areas for feeding, rearing, and migration. An estuarine area left untouched by man is rare since historically they have been the sites for major cities and port developments.

Because of their importance in the food production chain and their natural beauty, the limited estuarial areas require careful attention in the planning function. Close scrutiny should be given to all plans for development in estuaries which reduce the area of the estuary and interfere with water flow. Special attention should be given to plans for upstream projects which could deplete the freshwater supply of the estuary.

A Natural Corridor for Water

A floodplain is a shoreline area which has been or is subject to flooding. It is a natural corridor for water which has accumulated from snow melt or from heavy rainfall in a short period. Floodplains are usually flat areas with rich soil because they have been formed by deposits from flood waters. As such they are attractive places for man to build and farm until the next flood passes across the plain. In certain areas, these plains can be flood proofed by diking or building levees along the adjacent river or stream, but always with provisions for tremendous amounts of water that will sooner or later be generated by weather conditions.


Streamway modifications can be placed in such a way to cause channelization. Channelization tends to destroy the vital and fragile floodplain shoreline habitats and increase the velocity of waters in times of extreme flow. This may cause considerable damage downstream even in areas already given some flood protection. In unprotected floodplains, land-use regulations must be applied to provide an adequate open corridor within which the effects of bank erosion, channel shifts, and increased runoff may be contained.

Obviously, structures which must be built on a floodplain should be of a design to allow the passage of water and, wherever possible, permanent vegetation should be preserved to prevent erosion, retard runoff, and contribute to the natural beauty of the floodplain.

An island, broadly defined, is a land mass surrounded by water. Islands are particularly important to the state of Washington since two entire counties are made up of islands and parts of several other counties are islands. A fairly small island, such as those in our Puget Sound and north coast area, is an intriguing ecosystem, in that no problem or area of study can be isolated.

A World of Its Own

Every living and nonliving thing is an integral part of the functioning system. Each island, along with the mystique afforded it by man, is a world of its own, with a biological chain, fragile and delicately balanced. Obviously it does not take as much to upset this balance as it would the mainland system. Because of this, projects should be planned with a more critical eye toward preserving the very qualities which make island environments viable systems as well as aesthetically captivating to humans.

A lake can be defined broadly as a body of standing water located inland. Lakes originate in several ways. Many lakes are created each year by man, either by digging a lake basin or by damming a natural valley. Natural lakes can be formed in several ways:

  • By glaciers gouging basins and melting and depositing materials in such a way as to form natural dams
  • By landslides which close off open ends of valleys
  • Extinct craters which fill with water
  • Changes in the earth's crust, as can happen during earthquakes, forming basins which fill with water
  • By changes in a river or stream course which isolate parts of the old course forming lakes, called oxbow lakes


A lake, like its inhabitants, has a life span. This lifetime may be thousands of years for a large lake or just a few years for a pond. This process of a lake aging is known generally as eutrophication. It is a natural process which is usually accelerated by man's activities. Human sewage, industrial waste, and the drainage from agricultural lands increases the nutrients in a lake which in turn increases the growth of algae and other plants. As plants die, the chemical process of decomposition depletes the water's supply of oxygen necessary for fish and other animal life. These life forms then disappear from the lake, and the lake becomes a marsh or swamp.

Shallow Lakes

Shallow lakes are extremely susceptible to increases in the rate of eutrophication resulting from discharges of waste and nutrient laden-runoff waters. Temperature stratification does not normally occur in shallow lakes. Efficient bottom-to-surface circulation of water in these shallow lakes moves nutrients to the surface, photosynthetic zone encouraging increased biotic productivity. Large quantities of organic matter are produced under these conditions. Upon decomposition, heavy demands are made on the dissolved oxygen content of shallow lakes. Eventually, the oxygen level drops and some fish and other life forms die.

Lake Ecosystem

The entire ecosystem of a lake can be altered by man. By removing the surrounding forest for lumber or to provide a building site or farm land, erosion into the lake is accelerated. Fertilizers, whether agricultural or those used by homeowners, can enter the lake either from runoff or leaching along with other chemicals that interfere with the intricate balance of living organisms. The construction of bulkheads to control erosion and filling behind them to enlarge individual properties can rob small fish and amphibians of their habitats.

The indiscriminate construction of piers, docks, and boathouses, can deprive all of the waterfront owners and the general public of a serene natural view and reduce the lake's surface (see Use Activity Policies and Regulations).

Marshes, bogs, and swamps are areas which have a water table very close to the surface of the ground. They are areas which were formerly shallow water areas that gradually filled through nature's processes of sedimentation (often accelerated by man's activities) and the decay of shallow water vegetation.

Value to Animal & Plant Life

Although considered abysmal wastelands by many, these wet areas are extremely important to the food chain. Many species of both animal and plant life depend on this wet environment for existence. Birds and waterfowl choose these locations for nesting places. Wet areas are important as groundwater recharge areas and have tremendous flood control value.

Organic Soils

The high-water table and poor foundation support provided by the organic soils in these areas usually prevent development on them. The extraction of peat from bogs is possible when it is accomplished in such a manner that the surrounding vegetation and wildlife is left undisturbed and the access roads and shorelines are returned to a natural state upon completion of the operation.

The potential of marshes, bogs, and swamps to provide permanent open space in urbanizing regions is high because of the costs involved in making these areas suitable for use. Unlimited public access into them, however, may cause damage to the fragile plant and animal life residing there.

Muddy shores occur where the energy of coastal currents and wave action is minimal, allowing fine particles of silt to settle to the bottom. The result is an accumulation of mud on the shores of protected bays and mouths of coastal streams and rivers. Most muddy beaches occur in estuarine areas. However, some muddy shore areas may be found in coastal inlets and embayments where salinity is about the same as the adjacent sea.

Plant Life & Growth

Few plants have adapted to living on muddy shores. Their growth is restricted by turbidity which reduces light penetration into the water and thereby inhibits photosynthesis. In addition, the lack of solid structures to which algae may attach itself and siltation which smothers plants effectively prevents much plant colonization of muddy shores. While the lack of oxygen in mud makes life for fauna in muddy shores difficult, the abundance of food as organic detritus provides nutrition for a large number of detritus feeders.

Puget Sound is a complex of inter-connected inlets, bays, and channels with tidal sea water entering from the west and freshwater streams entering at many points throughout the system. Most of what is known as Puget Sound was formed by glacial action that terminated near Tenino in Thurston County.

The entire system, of which Puget Sound is actually a small portion, also includes the Strait of Georgia and the Strait of Juan de Fuca. The large complex may be divided into nine oceanographic areas which are interrelated: Strait of Juan de Fuca, Admiralty Inlet, Puget Sound Basin, Southern Puget Sound, Hood Canal, Possession Sound, Bellingham Bay, San Juan Archipelago, and Georgia Strait (from Puget Sound and Adjacent Waters, Appendix XV, Plan Formulation).

Central Puget Sound Basin

The economic development of the central Puget Sound Basin has been stimulated by the fact that the sound is one of the few areas in the world which provides several deep water inland harbors. The use of Puget Sound waters by deep-draft vessels is on the increase due to its proximity to the developing Asian countries. This increased trade will attract more industry and more people which will put more use pressure on the sound in the forms of recreation (sport fishing, boating, and other water-related sports) and the requirements for increased food supply.

Life in the Waters of Puget Sound

Puget Sound waters are rich in nutrients and support a wide variety of marine fish and shellfish species. An estimated 2,820 miles of stream are utilized by anadromous fish for spawning and rearing throughout the area. Some of these fish are chinook, coho, sockeye, pink and chum salmon, steelhead, searun cutthroat, and Dolly Varden trout. All these fish spend a portion of their lives in the saltwaters of Puget Sound and the Pacific Ocean before returning to streams of origin to spawn. The juveniles of these fish spend varying amounts of time in the shore waters of the area before moving to sea to grow to maturity.


Aquaculture or sea farming is now in the process of becoming reality in the Puget Sound complex. The mass production of seaweed, clams, geoducks, scallops, shrimp, oysters, small salmon, lobsters, and other possibilities looms as an important new industry. Shoreline management is particularly crucial to the success of sea farming. Aquaculture on any scale can be compatible and coexist with maritime shipping and shoreline industrial activities only by careful planning and regulation.

The shoreline resources of Puget Sound include few beach areas which are not covered at high tide. Bluffs ranging from 10 to 500 feet in height rim nearly the entire extent of the sound making access to beach and intertidal areas difficult. Because of the glacial-till composition of these bluffs, they are susceptible to fluvial and marine erosion and present constant slide hazards.

Storm Conditions

Although Puget Sound is protected from the direct influence of Pacific Ocean weather, storm conditions can create very turbulent and sometimes destructive wave action. Without recognizing the tremendous energy contained in storm waves, development of shoreline resources can be hazardous and deleterious to the resource characteristics which make Puget Sound beaches attractive (see Use Activity Policies and Regulations).

Additional Information

The concerns expressed previously in this section regarding each natural system are to be carefully considered when appropriate to the issuance of substantial development permits or the revision of the Master Program.

Surface-Water Runoff

Generally, rivers, streams, and creeks can be defined as surface-water runoff flowing in a natural or modified channel. Runoff results either from excessive precipitation which cannot infiltrate the soil, or from groundwater where the water table intersects the surface of the ground. Drawn by gravity to progressively lower levels and eventually to the sea, the surface runoff organizes into a system of channels which drain a particular geographic area.

The drainage system serves as a transportation network for nature's leveling process, selectively eroding materials from the higher altitudes and transporting the materials to lower elevations where they are deposited. A portion of these materials eventually reaches the sea where they may form beaches, dunes, or splits.

Distinct Stages Exhibited by Rivers

Typically, a river exhibits several distinct stages as it flows from the headwaters to the mouth. In the upper reaches where the gradient is steepest, the hydraulic action of the flowing water results in a net erosion of the stream bed and a V-shaped cross section, with the stream occupying all or most of the valley floor.

Proceeding downstream, the gradient decreases and the valley walls become gentler in slope. A point is eventually reached where erosion and deposition equalize and the action of the stream changes from vertical cutting to lateral meandering. As the lateral movement continues, a floodplain is formed, over which the river meanders and upon which materials are deposited during floods. Finally, when the river enters a body of standing water, the remaining sediment load is deposited.

Human Use

Extensive human use is made of rivers, including transportation, recreation, waste and sewage dumping, and for drinking water. Rivers are dammed for the production of electric power, diked for flood control, and withdrawn for the irrigation of crops. Many of these activities directly affect the natural hydraulic functioning of the streams and rivers as well as the biology of the watercourses (see Use Activity Policies and Regulations).

Spits and bars are natural formations composed of sand and gravel and shaped by wind and water currents and littoral drifting. Generally a spit is formed from a headland beach (tall cliff with a curved beach at the foot) and extends out into the water (hooks are simply hook shaped spits). While spits usually have one end free in open water, bars generally are attached to land at both ends. These natural forms enclose an area which is protected from wave action, allowing life forms such as shellfish, to reproduce and live protected from the violence of the open coast (see Use Activity Policies and Regulations).