Objectives For The Physical Integrity Of The Lake Erie Shore And Nearshore Areas (10/6/04 version)
Like streams and rivers, the physical features of coastal regions are based upon natural processes that occur over hundreds to thousands of years. The existing physical structure of Lake Erie varies greatly in Ohio, and is highly dependant on current and historical features. The glaciated nature of Lake Erie and its shore areas play a predominant role in the historical conditions of the Lake Erie shore and its nearshore areas, especially in the eastern counties of Ohio's Lake Erie shore. Current and historical water levels and wave climates also play a large role, and have worked together to form the physical setting that exists in large part today.
The physical condition of the existing shore can be traced directly to sediment resources and their distribution. Sediment is an important component in the formation of beaches, bar systems and shoals in coastal areas. Interruptions or changes in the amount, type, or distribution of sediment can have substantial impacts to the shore and nearshore areas. These interruptions or changes have affected the availability of sediment for sustaining protective beach environments along or near the shore of Lake Erie.
Sediment Resources along Lake Erie
Sediment enters Lake Erie from two principle sources, 1) streams and rivers, and 2) the erosion of the shore and nearshore areas. As described below, these are the main sources of the material that form the beaches and nearshore bar systems along the coast.
Impacts to Coastal Sediment Resources
Impacts to coastal processes from commercial and recreational structures, shore protection, dredging, and upland development have played and continue to play an important role in the condition of the Lake Erie shore and nearshore areas. An understanding of the impacts of each of these activities is important before arriving at solutions to existing problems. Each of these activities and their impacts are briefly discussed below.
A) Commercial and Recreational Boating Structures
As northern Ohio's economy grew in the 1800's, development of harbors to handle increases in commercial vessel activity in the upper Great Lakes region became important to the cities and rural areas along Lake Erie. Unfortunately, Ohio's Lake Erie shoreline contained few natural harbors that could be utilized by commercial vessels. As a result, most of the rivers emptying into Lake Erie were relied upon to offer safe areas for loading and unloading of commercial goods.
As increasingly larger commercial vessels became commonplace, the rivers were often not able to supply the safe facilities needed by the commercial traffic. Additionally, sand moving along the shore and out of the mouths of these rivers created natural shoals, which were often navigational hazards to commercial vessels. In response to the need for larger and safer facilities, artificial structures such as breakwaters and jetties were built at these river entrances.
Over time, the sand that would have naturally moved along the shore accumulated instead around the harbors. This accumulation was mainly due to the changes to littoral processes and wave climates caused by the presence of the breakwaters and/or jetties. Sediment would accumulate in and around these structures, and be unable to be redistributed to surrounding or downdrift areas.
Protective beaches that once were common along large stretches of the shore near these structures were not replenished with sand, and became narrower and less able to protect the upland areas behind them. In areas with strong longshore littoral transport rates, sand would accumulate updrift of the harbor structures, starving the downdrift shores of needed sand. In some cases, the beaches disappeared, leaving the upland areas exposed to waves and ice.
Sediment moving down the rivers was also unable to reach the shore as it had once done. Jetties associated with some harbors caused the majority of the sediment to be transported in suspension to deeper waters, where waves and currents could not deposit it back on the shore.
The result was and still continues to be shoreline areas that once supported beach environments, but now contain few if any protective beaches. Higher erosion rates can typically be found in these areas, with resulting losses of property and infrastructure.
B) Non-Point Pollution as it Relates to the Disposal of Dredged Sediments
As noted above, the construction of artificial harbors has created a situation where sediment that would have otherwise been distributed along the shore for beach replenishment is now trapped within or next to the harbor and its channels. In order to maintain safe navigation within these harbors, the channels and docks need to be constantly dredged to meet established depths.
The sediment from this dredging ranges in gradation from coarse-grained gravel to fine-grained silt or clay. The composition of the dredged material can vary greatly. When a river or stream empties into a harbor, the type of sediment within the harbor is largely dependant on the upland watershed and the activities within the watershed.
In some of the harbors, fine grained sediments are the predominant feature. This is especially true for harbors where the gradient of the river entering the harbor is very shallow. Toledo Harbor is a good example, where most of the coarser grained sand and gravels have fallen out of the water column upriver, and are not present in the navigational channel.
In other harbors, however, coarser grained materials such as sands and gravels can constitute a significant amount of the sediment accumulating in the harbors and channels. These sands and gravels, if free of pollution or fine grained silts and clays, can be used for nourishing beaches downdrift of the harbors. Unfortunately, the sands and gravels are usually intermixed with a significant percentage of silts and clays. This makes them unsuitable for beach nourishment.
A fair amount of the silt and clay can be traced to development in the watershed. Fine-grained particles from construction sites remain in suspension in the water column for a long period of time, often long enough to reach Lake Erie. Accelerated downcutting in streams due to increased runoff and shorter times of concentration also contributes to the sediment load that eventually ends up in the harbors.
Programs to reduce the amount of sediment in the systems, especially those which would result in a reduction in fine grained sediments in the rivers and streams entering harbors, may be beneficial to those areas where sand and gravel is a significant portion of the material being dredged from the harbor. Lowering the percentage of fine grained sediments would allow sand and gravel that now is placed in Confined Disposal Facilities or open lake disposal sites to be used for beach nourishment.
C) Shoreline Erosion Protection
Like most other coastal regions, the Ohio Lake Erie shore has areas that have eroded naturally for hundreds to thousands of years. Some of these areas erode more quickly than others, while some erode slowly and may actually accrete (or build) beaches over time. The rates of erosion or accretion are related to geology, wind and wave climates, shoreline orientation, sediment resources, the presence of headlands and embayments, and even changing water levels. Human activities that change any of these factors can have substantial effects on the rates of erosion or accretion in any particular section of the coast.
The erosion of the shore and its associated uplands supplies sediment to the nearshore areas for replenishing beaches and sand bar systems. On average, between 20 - 40 percent of the composition of a bluff or bank may be coarse-grained material that would be suitable for a beach environment. As the shore and associated upland areas naturally recede, this coarse-grained material would be available for sustaining beaches. These beaches would offer protection to the toe of the bluff or bank, only allowing waves or ice to reach the bluff or bank during significant storm events. By allowing the natural processes of erosion to occur, the overall rate of erosion can be reduced.
Human activities, and in particular the building of infrastructure such as roads, utilities, businesses and homes near the shore have created artificial constraints on the natural forces that shape the coast. Shoreline protection has become a reality as the permanence of shoreline development intercedes with the natural erosive forces along the coast. Letting the natural coastal processes of erosion and accretion continue is not an option available for shoreline property owners. Often the only option is the protection of the property with a hardened structure. Unfortunately, the very act of installing shoreline protection can have significant long term effects to the local shore environment.
Once the shorelines become hardened, the supply of coarse-grained material from the eroding bluffs is cut off from the nearshore. This can result in the same effect as when sediment from rivers and streams is diverted away from the nearshore. Unlike sediment from a single river or stream, however, the effects of this type of activities can be hard to detect at first.
Shoreline property tends to be distributed along the shore in parcels that have shorelines of a hundred feet or less in length. The reaction to an erosion problem is often an individual response to a local or regional problem. A person hardening the shore at their property has a small and almost imperceptible effect on sediment resources. As more and more property owners place shoreline protection, however, the cumulative effects to protective beaches through the loss of coarse-grained sediment can be significant.
These changes may occur over many decades, and can be associated with other dramatic events such as higher water levels, flooding, and infrequent but predictable storm events. Often the water levels and flooding events are pointed to as the reason for the loss of the protective beaches, and they play an important role. Unfortunately, with the hardening of the shoreline, the amount of sediment in the system becomes reduced. After a few recurring storm events, there simply is not enough sediment left to re-create the protective beaches.
When a local area starts losing its beaches, any remaining shoreline properties that do not have shore protection are faced with the prospect of higher erosion rates. These remaining natural shorelines become hardened through installation of shore protection, eventually cutting off any of the remaining supply of coarse grained material needed to sustain the protective beach system.
As with the elimination of sediment from rivers and streams, the loss of sediment from the erosion of the shore can cause the loss of protective beaches. Over time, protective beaches that once were common along large stretches of the shore are not replenished. The beaches became narrower and less able to protect the upland areas behind them, and often the beaches disappear, leaving the upland areas exposed to waves and ice.
D) Upland development
The placement of infrastructure such as roads, utilities, businesses and homes near the shore has created artificial constraints on the natural forces that shape the coast. Protection of the infrastructure through shore protection often comes at the expense of natural resources such as beaches that rely upon sediment derived from erosion.
Unfortunately, the attractiveness of shoreline property for development and commerce has created an almost predictable outcome. In Ohio, almost all of the available coast has been developed. Estimates are that over 80% of the shoreline has been developed, and the rate of development has not declined.
As the few remaining coastal properties become developed, their owners will eventually face the problem of an eroding shore. Over time, it is predictable that some measures will need to be taken to protect the homes or other infrastructure. These measures will likely lead to the hardening of the shore, and a further reduction of sediment for protective beaches.
The following list of objectives for reviewing the existing condition of the coast and proposing modifications or actions to restore the coast are based upon the aforementioned activities and impacts. The list of objectives is not exhaustive, and is only meant to provide prioritization to a few larger issues related to the physical integrity of the coast.
Objective 1: Restoration of Natural Shorelines:
The loss of the natural physical shoreline along the coast has been significant. Restoration of beaches, dunes and other natural features is an important component in the recovery of coastal resources, and in the reduction of non-point pollution resulting from high erosion rates. Re-establishment of protective beaches along portions of the shore can reduce the amount of erosion from waves and ice, decreasing turbidity in the nearshore areas and providing more natural habitat.
Natural shorelines are comprised of many features. Embayments and headlands, bluffs and banks, coastal marshes and barrier islands, beaches and limestone outcrops are all examples of natural shoreline features. Most of the features occur over stretches of shoreline that extend from thousands of feet to many miles.
Conversely, shoreline property tends to be distributed along the shore in parcels that are a few hundred feet or less. Responses to erosion problems often do not take into consideration local or regional problems. Individual desires of shoreline property owners also play a role in the response to a problem. One property owner may wish to have docking facilities associates with deeper water, while nearby owners may wish to have a recreational beach along their shore. These wishes are often not compatible.
Commercial and recreational boating interests and the communities they exist within have a strong interest in the continued presence of large navigational structures. These navigational structures create artificial headlands and embayments. These artificial embayments and headlands create intended disruptions in coastal processes that allow navigational channels to be viably maintained. The artificial headlands and embayments can have both beneficial and negative effects on the distribution of sediment resources.
Restoration of natural shorelines involves the proper assessment of local and regional physical settings, and devising strategies to replicate natural settings. Substantial amounts of information have been gathered on the historical and current physical settings that exist on the coast. The information needs to be collected, analyzed, and translated into specific recommendations and actions for local coastal areas.
It is suggested that ODNR, in consultation with the USACE and other coastal partners, proceed with a comprehensive look at the harbors and associated watersheds within Ohio to determine the following:
Objective 2: Identifying and preserving undeveloped properties along the shore
Historic and current development of the shoreline has created situations in which the likely conclusion is the installation of erosion control structures to protect the upland areas from natural forces such as waves and ice. This protection causes a loss of available sediment for the nearshore, and generally leads to the reduction or elimination of natural protective beaches.
In the past, the erosion of the coast and the nearshore areas provided an important source of the material that accreted along the shore to form beaches and bar systems. Often, the beach fronting a stretch of shoreline owed its origin to the erosion of another bluff/shore/nearshore area. The shore areas were fronted by wide beaches that were distributed across the coastal counties.
Early development activities along the shore were mainly confined to the cities, and the effects of hardening the shore were not apparent. The dynamic nature of erosion and accretion made the impacts to a particular location difficult to see. Today, however, development covers the vast majority of the shore, and most of the shoreline has been hardened to protect the existing buildings or infrastructure. The resulting loss of sediment to form beaches and bar systems is substantial, and will result in the reduction of sediment available to nourish existing and future beaches and bar systems.
Objective 3: Addressing the loss of sediment to the nearshore from the installation of shore protection
The installation of shore protection has become a necessity as homes, businesses and other infrastructure become threatened by erosion. Once constructed, the value of the investment in the building or infrastructure becomes higher than the installation and maintenance costs of the shore protection. The installation of the shore protection has had the unfortunate result of cutting off sediment supplies to the nearshore, and has led to a reduction in protective beaches.
Each project to install, rehabilitate or upgrade an erosion control structure has a long-term effect on the available sediment resources for beaches and nearshore bar systems. During the life of any structure, the sediment that would have been available to the nearshore system through natural erosion is not available. This results in a loss of sediment for protective beaches and bar systems.
Current review processes for such structures account for sediment already in Lake Erie that might be trapped by structures such as groins or breakwaters. Pre-filling of groin compartments or nearshore breakwater systems with coarse-grained sand is already a requirement for approval of such structures. No comparable requirement exists, however, to look at the impacts associated with the hardening of the shore and the subsequent reduction in sediment available for sustaining protective beaches.