Let’s not confuse bulkheads with seawalls.

by Carl Shipley, PhD, Poulsbo

I moved to Kitsap County a little over a year ago and almost immediately became aware of the heated debate about how shoreline development might be affecting the nearshore environment.

I found that residential bulkheads are universally condemned by the environmental movement and Kitsap County because they are thought to harm nearshore health.  Yet, I also learned that a detailed study of Bainbridge shoreline found that bulkheads had no clear effects on standard measures of environmental health, such as the presence of eelgrass beds or forage fish spawning areas.

I’ve spent a lot of time in the last year reading and attending lectures in order to try to understand this apparent contradiction.  Of course, I have not been able to do a complete review of all the literature on bulkheads and environmental health, but below are some thoughts that might help explain why bulkheads are condemned by environmentalists yet good research fails to find that they have clear harmful effects.

If one examines the literature on shoreline armoring it is clear that some kinds of armoring can have pronounced effects on the nearshore environment.  However, the term “armoring” is commonly used to refer to a variety of structures, massive seawalls, groins, jetties, as well as small residential bulkheads.

The effects of these different kinds of structures are not the same, nor are the effects of a given type of armoring the same across different geographies.  Moreover, our knowledge of how these various structures should be built in order to have minimum impact on the environment has advanced markedly in the last 50 years so that modern structures can be expected to have different effects than older ones.

Nevertheless, differences in the effects of various types of armoring structures due to their size, the geography of where they are places, or when they were built are very often completely ignored in discussions of shoreline ecology.  For example, it is common to find people in the environmental movement condemning small residential bulkheads based on evidence from huge seawalls.

Here are some examples I’ve seen personally in the last year.

I attended a lecture at the Bainbridge City Hall in July 2010 given by R. Thom, the senior author of a detailed study of Bainbridge shorelines done by the Battelle research institute.

At the meeting, Thom was asked how he would explain the fact that, in his study of Bainbridge, bulkheads appeared to have no clear effect on measures of environmental health such as eelgrass beds.  He said he couldn’t explain the result but believed there must be some unknown local factor at work.

He defended the idea that bulkheads are harmful to the nearshore by talking about the effects of a structure, which he called a bulkhead, at Lincoln Park in Seattle.  When someone in the audience pointed out that the structure is really a massive seawall he basically ignored the issue.

However, it’s really not reasonable to compare the Lincoln Park seawall, a huge edifice, extending a mile in length, that was built by the WPA in the 1930s, to residential bulkheads built under modern ordinances in Kitsap County.

Local property owners might reasonably argue that Thom’s unknown factor at work on Bainbridge is the fact that it’s illogical to use evidence from massive seawalls to predict the effects of residential bulkheads.

In the last year I also attended a Washington State Extension class lecture at North Kitsap High School given by a prominent local environmental spokesman who was extremely critical of residential bulkheads.

When I asked about the source of some of his arguments he told me I needed to read a book that discusses bulkheads called, “Living with the Shore of Puget Sound and the Georgia Strait.”  (Here’s a link to a searchable, online version of the book.)

I have read the book and it presents a lot of useful information, especially about the geography of the Puget Sound area, however, it treats seawalls and bulkheads as essentially equivalent structures.

For example, in its discussion of different types of armoring it has a separate subsection on riprap and another subsection on groins but treats seawalls and bulkheads in the same subsection, the first sentence of which is, “these two structural techniques are similar (p. 28 of the 1987 Duke University paperback edition).

In this subsection of the book, the word “bulkhead” appears four times, always in conjunction with the word “seawall,” in phrases such as  “Unfortunately, seawalls and bulkheads are often not well designed or constructed …(p.29) or “A seawall or bulkhead protects only the land behind it” (p. 29).

Moreover, much of the evidence the book presents is based on studies of seawalls as opposed to anything resembling a residential bulkhead. For example, the book contains a long discussion of the fact that seawalls, groins, and jetties at Cape May, NJ, led to changes in the beach.

Cape May was the first commercial beach resort in America.  It opened in the early 1800s, over 200 years ago, and most of the structures discussed in the book were built over a hundred years ago.  They were massive installations, seawalls, groins, and jetties, generally built out into the water, and constructed in a hurricane zone to boot.  They really have little, if anything, to teach us about Bainbridge Island bulkheads and environmental health.

Yet talking about the effects of bulkheads based on evidence from giant seawalls is more common than one would think, largely, I believe, because much of the environmental literature insists on equating the two kinds of structures.

In the last year, I had a long talk with a very bright, obviously well-intentioned local resident who told me he understood how bad bulkheads are because he had seen the harm done to the environment by the Galveston seawall.

To understand how illogical this kind of comparison is, consider this sentence fromWikipedia describing the Galveston seawall: “a 10-mile (16 km) long, 17 foot (5.2 m) high seawall was constructed to protect the city from floods and hurricane storm surge.”

So one reason many environmentalists and property owners in Kitsap County disagree about the effects of bulkheads is that often, when they discuss the subject, they are thinking of different things.

This is not to say that there is no evidence indicating that bulkheads affect the beach.  One frequently cited situation is the case in which a large bluff, generally called a feeder bluff in the environmental literature, is actively eroding onto the beach and a wall interferes with this process, thus changing the composition of the beach over time.

Certainly there are numerous feeder bluffs in the Puget Sound region; in fact, large parts of  “Living with Puget Sound …” are primarily discussions of where these bluffs are located.  However, I believe the situation in which a large wall effectively holds back a feeder bluff is fairly rare in Kitsap county.

The vast majority of Kitsap shoreline is not in front of a feeder bluff.  It is very difficult to build a wall large enough and strong enough to hold back a big eroding bluff.  And I assume it would be impossible to get a permit to build this kind of structure now and that has been the case for some time.

To the degree that such “bluff walls” do exist in Kitsap County, I believe they would have to be so massive that they would be in a different category than normal residential bulkheads.  It seems reasonable to apply regulation of this kind of bluff wall to properties that have such a wall; it does not seem reasonable to believe that these walls should be used to condemn residential bulkheads.

A second frequently cited case in which bulkheads can affect the beach is the situation in which a bulkhead is built in such a way that it is hit by high-energy waves. If this happens, wave energy is reflected off the bulkhead in an unnatural way and this can cause scouring of the beach directly in front of the bulkhead, changing beach composition.

Certainly, there are places in Kitsap County where storm action produces waves that scour the beach, but I believe this kind of scouring action generally causes fairly minor changes, changes that are confined to a narrow area directly in front of the bulkhead.  Most beaches in the county are not on high-energy wave systems (which is why the main complaint about waves in this area generally refers to ship wakes and not storm waves).

Strong waves build up when wind pushes water over long distances, generally many miles.  These long distances of open water simply don’t exist in front of most Kitsap shorelines.  As a result, waves hitting most Kitsap beaches are fairly small even in storms.

I believe the rarity of sea walls, feeder bluff walls, or high-energy wave situations in Kitsap County explains why empirical research like the Battelle study of Bainbridge shoreline has failed to find clear negative correlations between bulkheads and environmental health.

In the typical Kitsap bulkhead situation the effect of the bulkhead, if any, will be confined to a small area in front of the structure.  Eelgrass beds and fish spawning areas typically extend out into the nearshore waters for many meters.  This explains why half the eelgrass beds on Bainbridge are found in front of a bulkhead; eelgrass has no reason to care about typical bulkheads in Kitsap County.

Nevertheless, all bulkheads are routinely condemned by ardent environmentalists and also by many county administrators.  So a property owner in Dyes Inlet, who is not near a feeder bluff and who has property on very protected water with low wave energy, still has  his or her property coded as red (equals highly disturbed and harmful) in the county shoreline assessment if he, or even his neighbor, has a small residential bulkhead.  I don’t believe this policy is really based on science and, to me, it seems illogical and unfair.

There is also an argument about bulkheads that, I believe, is based more on aesthetics than clear evidence of harm, which says that all of the land surrounding Puget Sound is gradually eroding down onto the beach so a bulkhead anywhere is, by definition, interfering with a natural process of erosion and thus changing the natural composition of the beach.

The problem with this argument is that the erosion carrying soil to the beach from all but the most steeply graded property in the county involves small amounts of soil transported over a very long time frame – what we would normally call a geologic time frame.

A reasonable reaction to this possible slow change in beach composition is feeding the beach – artificially introducing some sand or small rock to replace anything that a bulkhead may have stopped from naturally eroding onto the shoreline.

I was at a talk given by a Fish and Wildlife scientist in the County Building at Port Orchard last spring and a person in the audience asked if feeding the beach wouldn’t be a good solution for some of the problems environmentalists feel bulkheads cause.  The speaker said that feeding the beach wouldn’t work but gave no reasoning.

Again, I think this is an extreme response based on extreme cases – large feeder bluffs or large wave erosion.  Even “Living with the Shore of Puget Sound and the Georgia Strait” says that artificially feeding the beach can often be a good technique.

I’m sure there are a few places in the county where adding material to the beach will not be able make up for loss of natural sediment caused by a bulkhead but I believe that for most of Kitsap shoreline feeding the beach, if it is needed at all, is probably a perfectly reasonable approach to maintaining the beach in a healthy state.

As I said at the beginning, I’m not claiming that this is a complete review of literature on bulkheads.  However, as I continue to learn more about the subject I am beginning to believe that a complete review would not, in fact, provide compelling evidence that most residential bulkheads have clear negative effects on nearshore environmental health.

One thing that makes me wonder if clear evidence of harm really exists is the fact that, whenever I ask for this evidence, environmental spokesmen are unable to provide it.

I was at a Futurewise meeting in the Poulsbo Public Library several months ago where the speaker was extremely critical of bulkheads.  I asked what evidence supported his position.  His reply was that he couldn’t provide that information because, to do so, he would have to give me a semester course in environmental science.

I don’t believe understanding how small residential bulkheads affect the environment involves some kind of rocket science that can only be understood after extensive coursework.  It seems more likely to me that the speaker avoided my question because he didn’t have a convincing answer.

The issue of whether small residential bulkheads have important harmful effects on the nearshore is an important one because Washington State Ecology and Kitsap County seem to have made bulkheads the primary focus of shoreline management.

In Kitsap County inventories of proposed shoreline environmental “stressors,” bulkheads generally get the most weight of any type of development.  If these bulkheads are not clearly harmful the county is wasting millions of dollars developing and enforcing pointless regulations — dollars that could be spent on projects like improving stream habitat, work that has clear, measurable benefits.

For example, Kitsap County government has done excellent work improving habitat and fish access in Chico Creek.  Partially because of these successful projects, the chum salmon run in this watershed is now the largest in western Puget Sound.

I don’t believe there is any official count but I’ve heard estimates that about 60,000 chum salmon came into Chico Creek in 2010, and it’s worth noting that all these fish swam right by heavily developed property on their way to spawn.

The county has many opportunities to carry out projects like those that have improved Chico Creek.  In an era of limited resources, these kinds of projects seem like the best place to allocate funds.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s