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Lake Erie Shore Erosion Managemen

(download printable factsheet) About the LESEMP In an on-going effort to assist property owners along Ohio’s Lake Erie coast by providing free technical assistance, the Lake Erie Shore Erosion Management Plan (LESEMP) is being developed by the Ohio Department of Natural Resources through a partnership between the Office of Coastal Management, Division of Wildlife and Division of Geological Survey. The LESEMP identifies the causes of erosion in specific areas called reaches which are stretches of shore with similar site conditions. The LESEMP then outlines the most likely means of successful erosion control based on reach-specific erosion issues, geology and habitat. The objective of the reach-based approach to erosion control is to simplify the decision process while enhancing the effectiveness of solutions to erosion related issues. The LESEMP does not contain any regulatory oversight provisions. The LESEMP is being developed by the project partners, Ohio Department of Natural Resources Office of Coastal Management, Division of Geological Survey and Division of Wildlife. Federal grant funding for this project is provided by the National Oceanic and Atmospheric Administration.

t Plan

Introduction

Underlined bold words found in this document are included in the LESEMP Glossary. To download go to: www.ohiodnr.com/tabid/23319/default.aspx

Coastal erosion is a continual process, affecting all of the shore at some point in time. In response to the wide-ranging erosion locations and rates, private and public shore property owners along Ohio’s 312 mile Lake Erie coast have constructed a wide variety of erosion control measures. Some of these erosion control measures are properly engineered and constructed, while others are less appropriate or adequate for the site conditions exacerbating erosion onsite or on nearby shores.

Recognizing the need to encourage the best possible erosion control options, the Ohio Legislature enacted Ohio Revised Code (ORC) §1521.29 in June 2000. It was amended and renumbered to §1506.47 in September 2007. This statute mandates that the Ohio Department of Natural Resource (ODNR) prepare a plan for the management of shore erosion in the state along Lake Erie, its bays and associated inlets; revise the plan whenever it can be made more effective; and make the plan available for public inspection. In conjunction with development of a plan, the code states that ODNR, “may establish a program to provide technical assistance on shore erosion control measures to municipal corporations, counties, townships, conservancy districts, park boards, and shoreline property owners.”

In the late 1990s, ODNR began the preliminary stages of erosion management plan development. This initial work focused on technical aspects, calling for an increase in the geographic information system (GIS) capabilities of the state. More recently, ODNR began development of the formal Lake Erie Shore Erosion Management Plan (LESEMP), for local communities and individual property owners to aid in the management of coastal erosion. The LESEMP is based on the premise that specific regions along Ohio’s Lake Erie coast are dealing with similar issues that could be handled in a more coherent manner. The plan is being developed according to a regional framework for Ohio’s coast, with each region based on general erosion characteristics and represented in an individual chapter.

The LESEMP incorporates a wide range of information and topics including coastal geology, erosion processes, critical habitat, and the cultural characteristics of local communities. In order to fully bridge these topics, specialists from the ODNR divisions of Geological Survey and Wildlife and the Office of Coastal Management came together enact this initiative. Additional expertise was included through the creation of an external workgroup. Workgroup members include state and federal government personnel, university researchers, non-governmental representatives, and a member of the public.

The final and critical piece to the LESEMP’s development is the input from those with a vested interest in erosion issues. Specifically, information was garnered from littoral property owners, and public officials from coastal communities; and contractors and consultants who work along the lakefront. These target audiences were reached via a Local Community Needs Assessment, conducted by the Ohio State University Sea Grant College Program in 2007. This social assessment consisted of focus group sessions and a questionnaire.

Additional information is being acquired from local officials during the recommendation development process for each region. The local officials contribute information regarding their communities and the type of mitigation measures that would be most compatible with the character of their county, municipality or township. This information is augmented with public meetings, where the local property owners and others can provide input and feedback on the LESEMP products. The public meetings typically occur after the meetings with public officials.

The LESEMP is designed as an informative and voluntary plan with recommended actions for property owners and local officials. The recommendations contained within will serve as a best practices reference for the management of erosion along Ohio’s coast. To enhance the use of the recommendations, the plan includes technical and financial incentives. Even though permitting agencies and procedures may be mentioned throughout this document, the LESEMP is a non-regulatory initiative and will not be used for implementation or enforcement of regulatory measures.

Previous State of Ohio Lake Erie Shore Erosion Reports

Prior to the initiation of the current phase of the LESEMP, several erosion plans had been developed within Ohio. Most of the earlier reports were focused on cataloguing the erosion issues while later documents provided erosion control recommendations.

The first erosion report for the state of Ohio dates back to July 31, 1940. This report, The First Annual Report of the Erosion Division, highlights the issues with recession along Ohio’s coast. It documents the history of the purchase of Ohio lands and continues through the late 1930s when several federal projects were commenced as a form of economic development. Since most projects developed during that era have likely been modified between the time of the report and present, the LESEMP mainly uses the 1940 report information for the identification of historic erosion hot spots and recession rates.

In the early 1950s the ODNR Division of Shore Erosion released a Master Plan for the control of Lake Erie erosion. The Master Plan Appendices contain the location of structures and shoreline position circa 1950 as well as a series of proposed structures for the length of shore from Sandusky Bay to the state line in Conneaut. The Appendices are arranged according to coastal features such as rivers and harbors, with each appendix covering one section of the coast. Proposed structures are based on the sites contained with the appendix. Unlike future reports, there is no comprehensive or summary section that combines all recommendations. There is also minimal explanation of the erosion rates and no justification for the proposed shore structures.

Around this time, reports were also produced by the United States Army Corps of Engineers. While these reports are useful to the management of Ohio’s Lake Erie coast, they are dated and may be best applied to current erosion studies as historical information only.

The next erosion-related documents produced by the state of Ohio consist of a series of reports developed during the late 1970s and early 1980s. In the Reports of Investigation and Open File Reports, ODNR Division of Geological Survey staff detail the erosion and flooding issues along the coast. Each report represents an individual coastal county, with the exception of Erie and Sandusky counties which are covered within one report. The documents are divided into reaches, based mainly on natural features (i.e. rivers). Recession rates from 1877 through 1973 are calculated and reported for each reach, then summarized for the county as a whole. Based on the recession data and site conditions at the time of the report, recommendations are provided for the best means of mitigating erosion within each county.

This introductory chapter gives a broad overview of erosion processes including the movement of sediment and water, as well as a general physical characterization of the Ohio Lake Erie shore. The information contained within is intended to provide a basic understanding of erosion.

Causes of Erosion

Erosion Basics

Erosion is the “wearing away of land or a lakebed by the action of natural forces.” The most noticeable and dynamic processes that lead to erosion include wave induced erosion and mass wasting. These processes and the factors that enhance (or diminish) their respective effects on the coast of Lake Erie are discussed below.
The process of erosion can occur within the bluff, shore (including dunes), or nearshore areas. The characterizations of these three distinct zones of the coast are based upon their differences in erosion processes and rates. Even though these regions are discussed separately below, they are contiguous and highly dependent upon one another.

The bluff is mainly the section of land that does not directly interact with the lake except during storm events or extended periods of high lake levels. Bluffs are generally those upland areas containing complex soil sequences, which rise 20 feet or more from the shore. A bank is similar to a bluff, but generally has less complex soil sequences with relief up to 20 feet. For the purposes of this erosion discussion, bluff and bank will be used synonymously. Further distinction will occur within later chapters as is necessary for providing recommendations.
The area between the bluff and lake is an area referred to as the shore. The shore is essentially where the land meets the lake, and is often the site of the most visible erosion. A shore zone with unconsolidated (loose) material, such as sand is often called a beach. A dune is typically found in areas with sandy materials, located at the back of a beach. These mounds of sand or other loose sediment are formed through waves and winds. Over time, grasses will naturally grow on a dune, but artificially transplanted plants will also thrive should the vegetation be left untouched.

The nearshore is the area typically under water, extending offshore from the shore zone until the point at which the lakebed flattens and sediment is no longer able to move with the currents due to deeper water depths. This zone can extend to roughly 60 feet or more offshore depending on the slope of the lake bottom. Erosion within the nearshore is often unnoticed since it occurs under the surface of the water, but it can be a significant cause of major erosive events along Ohio’s coast.

Bluff & Bank Erosion

Mass wasting is generally characterized by distinct erosive events whereby the bluff “slumps,” losing significant amounts of material in one event. This type of erosion is often caused by ground water seepage. As water moves through the bluff towards the lake, instability between different layers of soil can arise leading to the slumping of material. Ground water and surface water can come from rain, snow melt, a high water table, sprinkler systems, or poorly designed septic systems. Surface water can erode channels in the bluff face resulting in significant surface erosion. The severity of these events is often contingent upon the velocity and volume of water moving on or through the bluff.

Vegetation on the top and face of the bluff can be both positive and negative in terms of bluff stability. For the most part, planting shrubs, trees and herbaceous plants (“perennials”) leads to greater stability of the bluff. The roots of these plants remove water from the bluff while creating an interconnected support system that stabilizes the soil. A variety of plantings with different root penetration depths creates bluff stability beyond just the top layer of soil. Larger trees and plants can also have a “canopy effect” where smaller plants are sheltered from direct sunlight and the ground is protected from desiccation. Organic matter, such as fallen plant leaves, often remain in areas of thick vegetation. The decomposition of organic materials creates fertile and loose soil that is better for plant retention and erosion reduction. Finally, a vegetated bluff can often weather a storm much better than one that is bare because the vegetation protects against wind-induced soil erosion.

In cases where the bluff is already unstable, heavy vegetation, such as large trees, can lead to further instability. This is often the case when trees are located at the bluff edge or along the slope. In instances such as this, it may be best to remove the bulk of the tree, while leaving the root system in place. This will allow the soil to remain intact, while reducing the weight on the bluff. Trees along the shore and lower on the bluff often do not have as dramatic an effect on stability since the force of their weight is less of an issue. Often trees on this lower portion of the bluff are a benefit because they reduce ground water levels and do not require as much maintenance.

It is important to note that although vegetation can stabilize the top soils of a bluff, it cannot protect the toe of the bluff from wave erosion. This process of erosion, as described in the next section, can only be managed through beach nourishment or the placement of a shore structure.

One additional cause of mass wasting is the yearly freeze-thaw process that is common in the Great Lakes region. Essentially, this process involves the freezing of water within the bluffs. As water freezes it expands, creating a larger fissure, or crack, within the bluff. If this occurs within a large enough fissure, slumping may occur. In some instances, water on the bluff face may also freeze, causing a build up of groundwater within the bluff. This circumstance may also lead to instability and slumping of upper bluff materials. Typically, freeze events can begin in the late fall and are common through the winter months. Once spring arrives, the ice thaws and runoff from within or on the bluff can cause erosion such as that described above.

Shore Erosion

Waves directly cause erosion of the shore by continuously extracting material each time the water interacts with the land. This can cause erosion of both the face (slope) of the bluff and the shore area including beaches and dunes. Additionally, the effects of waves can be more or less pronounced depending upon the lake level, storm activity, bluff and shore composition, and nearshore profile (i.e. presence of bars or shoals). For instance, higher lake levels will generally lead to a greater level of erosion at the toe of the bluff, the bluff face, the face or entire extent of a dune. Landforms composed of bedrock or cohesive sediments (clay or till) are generally much more resistant to erosion, whereas those composed of noncohesive/unconsolidated materials (sand and gravel) erode at a much higher rate. Additionally, the nearshore profile, or depth of water just offshore, can have a significant impact on the size of wave reaching the shore. Changes to the nearshore will reduce (shallow water) or amplify (deep water) the energy of the waves reaching land. The interactions between the nearshore and shore are explored in further detail in the discussion of nearshore erosion.

One additional erosive factor to consider in the Great Lakes region is the effect of ice. Due to Lake Erie shallowness, it is predisposed to freeze most winters. The effects of this occurrence are two-fold. When the lake first freezes along the shore, ice can protect the shore from erosion because the waves are unable to reach land. Pile-ups, or large piles of broken ice on the shore, act as barriers which reduce the force waves exert on the shore. This ice, sometimes referred to as the nearshore ice complex, may also blanket the sediment in the nearshore, further reducing the overall erosion rates In other instances, such as in areas with a gradual nearshore slope, waves hitting the nearshore ice complex can scour the lakebed causing a loss of sediment from the nearshore. Additionally, once the ice begins to break-up, it can take with it significant amounts of material, most of which is from the shore, including dunes, and from the toe of the bluff. Similar erosive events occur when the wind has enough force to move the ice, scouring the lakebed and shore. If enough shore erosion of occurs, mass wasting events throughout the spring and early summer may be witnessed because the toe of the bluff is undermined and the upper bluff material becomes unstable.

Nearshore Erosion

Nearshore erosion, also referred to as lakebed downcutting, is the process whereby waves scour bottom sediments. Once the thin layer of sediment covering the lakebed is caught in the turbulence of the breaking wave, it acts like sandpaper that constantly wears away loose sediments and bedrock until the depth of the nearshore increases. The increased nearshore depth allows larger, more powerful waves to break closer to land. This causes greater erosion of the shore and bluff areas, which may lead to instability at the toe of the bluff or shore structure. In this situation, an unstable bluff could slump or the shore structure may fail. Areas where there is relatively little sediment covering the bedrock, the process of lakebed downcutting is often much slower. This is because the abrasive sediments are absent and erosion is only caused by the force of breaking waves.
Nearshore erosion can often be the most detrimental to the coast because it is typically an irreversible process. Sediment that is removed from the nearshore system is often transported offshore and out of the littoral system. After removing the sediment, waves begin to erode the cohesive material of the lakebed. This material cannot be returned to the nearshore and as such, the nearshore deepens.

Lake level fluctuations can significantly alter the rate of nearshore erosion. During times of higher lake levels, waves break closer to the toe of the bluff, potentially resulting in greater bluff and beach erosion and lower erosion in the nearshore area. In the reverse situation, where the lake levels are lower, waves break farther away from the toe of the bluff, with an increase in lakebed downcutting and often a decrease in the level of bluff and beach erosion. If lower lake levels persist, and the nearshore depth increases significantly, any increase in lake levels will allow for larger waves to reach the shore zone. This in turn increases shore and dune erosion and can often lead to bluff erosion if the toe of the bluff is undermined.

The affects of nearshore erosion on the bluff are most readily noticeable by the vertically concave profile of a cohesive bluff. These bluffs frequently have a steep slope, are close to the water, and are located in areas with higher than average erosion rates.

General Erosion Rates

General erosion rates for each coastal county are provided in Table 1. The long-term recession rates cover the years 1877 to 1973 with the short-term rates representing data from 1973 to 1990.

County Recession Rates, Distance Measured Perpendicular to Shore.

Sediments and Erosion

The composition of the bluff, shore, and nearshore can directly influence the erosion rates at a given location. For instance, noncohesive sediments such as sand and gravel are easily erodible, whereas cohesive materials such as clays can be more resistant to erosion. The more resistant clays, however, can become fluid with excess amounts of water, acting as a lubricant in the movement of layers of sediment. Shale is another geologic feature that erodes differently from either the noncohesive sediments or clays. In areas of limestone and dolomite, erosion may not even be measurable over short periods of time, but is more apparent when viewed in the long-term.

Currents and the Littoral System

Lake Erie is connected to the other Great Lakes which together from a freshwater network of lakes, rivers and streams that drain to the Atlantic Ocean. The upper Great Lakes, (Superior, Huron and Michigan) drain from Lake Huron down the St. Clair River to Lake St. Clair then down the Detroit River to Lake Erie. Erie in turn flows over the Niagara Falls or out the Welland Canal then down the Niagara River to Lake Ontario. Ontario flows out the St. Lawrence River to the ocean.

Around 80 percent of the water that enters Lake Erie comes from the Detroit River, with lesser amounts attributed to the Maumee River, precipitation and inflows from other tributaries. The strong influx of water at the western end of the lake and outflow at the eastern end, combined with prevailing winds from west to east, cause an overall movement of water from west to east within Lake Erie. This flow is so slow that it is almost unperceivable. More noticeable are the currents that flow along the coast, often referred to as alongshore or littoral currents. These currents are responsible for the movement of sediment parallel to the shore. According to the 1966 report by the ODNR Division of Geological Survey, alongshore currents “seem to be the most important agents of erosion, transportation, and deposition of sediments along the shoreline of Lake Erie.”

Sediment is also moved on and off the shore through cross-shore currents. These currents run perpendicular to the shore and can be responsible for the erosion or accretion of beach-building materials. Once the material is removed from one location via cross-shore transport, it will be caught up in the littoral current. The material then moves to a beach or shore downdrift of the source location. The original location of the material is referred to as the “source”, and the final settling location for materials is called a “sink”. In the case of material that is captured in a strong cross-shore current, it may be moved so far offshore that it leaves the littoral system. When this occurs, the offshore location is acting as a sediment sink, permanently capturing materials that could be otherwise used along the coast.

Materials captured within the littoral system are the main beach-building components along any coast, with alterations to the shape, size, and orientation of the beach caused by the interactions of these two predominant currents. Beaches are ever changing coastal features comprised of unconsolidated materials such as sand, gravel, and cobble sized materials. Due to their composition, beaches are considered to be in dynamic equilibrium. Essentially, this means that although a beach may appear to be stable, individual particles of sand are constantly moving with the currents. More drastic changes to a beach are often noticed after storm events.

Wind is also a significant player in the movement of lighter beach materials. This is especially true with sandy beaches and is most evident in areas with a well established dune system such as those at Headlands Dunes State Nature Preserve in Lake County. The dunes are built through the movement of sand, which occurs through aerial (wind) and wave transport. Vegetation on the dune also aids in the stability of these features.

Sediment Inputs

In order for littoral transport to move sediment, the material must first enter the water. There are two primary means through which material enters into the littoral system: riverine inputs and bluff/shore erosion.

The inflow of sediment from rivers into Lake Erie is the lesser of the two mechanisms. Typically, most of the material entering the littoral system enters through erosion of lands adjacent to the lake, with approximately a quarter of the soils of the bluff comprised of sand. The continuous process of wave erosion provides a constant supply of sand, while a bluff slump may add larger amounts into the system during a single event. After the sand has entered the littoral system, it is transported via the littoral current, often ending up at a location downdrift.

Structures

The primary purpose of many shore structures is to reduce the recession rate of the shore. For the most part, recession rates have decreased in areas protected by such structures; however there have been impacts to sediment levels due to human influences on the shore. Sediment is lost from the littoral system when impounded by shore structures, such as seawalls, or through certain dredging procedures. The effects of shore structures are quite pronounced along the Ohio shore, deserving an in-depth review of the current status of structures and the related loss of beaches.

Since development of the Lake Erie shore began in the mid-1800s, shore structures have been employed to protect private individual and commercial investments. As populations increased along the coast, there has been a noted increase in the number of structures. In the late-1870s there were approximately 60 structures statewide. That number significantly increased in the late-1930s to around 1,400 before jumping to around 3,600 in the mid-1970s. The construction of shore structures peaked during the late 1970s, due to the heightened need to protect coastal investments because of higher lake levels during those years. Even with the lake level fluctuations of the 1980s and 1990s, the rate at which structures were built decreased, while the actual number of structures continued to increase along Ohio’s coast. Since structures are rarely removed and may last for decades, the continual armoring of the shore has created the predominantly hardened lakeshore characteristic of present day Ohio.

Currently, the coast of Ohio is significantly armored, which affects the shore’s characteristics. For instance, there is evidence that the coast in the 1800s was fairly linear and tended to recede at a uniform rate. Today the shore is irregular with structures and pocket beaches throughout, and is characterized by protected areas interspersed among rapidly receding, unprotected areas.

Although the increased number of structures has generally reduced recession rates, it has also decreased the size of beaches. Reduction in beach size results when the sediment supply is interrupted. Natural erosion of bluffs and banks is an important source of beach-forming sand. Shore-parallel structures minimize bluff, bank, and shore erosion, interrupting these sources of sand and preventing eroded materials from reaching the water where they could be distributed by the littoral system. Those sediments that do enter the littoral system are often trapped by shore-perpendicular structures, which build beaches on one side but leave downdrift areas sediment-poor. Ultimately, both shore-parallel and shore-perpendicular structures lead to a reduction in beach widths coast-wide, increasing the coast’s vulnerability to erosion and inundation.

Larger structures often lead to greater effects, with harbor structures causing the most noticeable alterations to the coast. According to Hartley (1964):

“Most of the large structures along the Ohio shore have caused build-up of beaches on their updrift sides and accelerated erosion downdrift. The effects are not balancing, in that the length of eroding shore is ordinarily five or more times the length of shore which is protected by build-up.”

Two prominent examples of these larger structures include the jetties and breakwaters at Fairport Harbor (on the Grand River) and Conneaut Harbor (on Conneaut Creek). The structures on the updrift (west) side of Fairport Harbor have created the large depositional beach found at Headlands Beach State Park. Downdrift of these structures, severe erosion has occurred, as witnessed east of Painesville Township Park. The effects of the harbor structures in Conneaut are not only found within Ohio (i.e. beaches updrift) but have also diminished sediment supply within Pennsylvania’s coastal zone. Sediment shortages likely caused by the Conneaut structures are present as far as Presque Isle, Pa.

Structural shore protection predominates on the Ohio Lake Erie coast because this method of controlling erosion works well for most of the coast. Although appropriate use of structural erosion control has prevented a significant amount of upland erosion, poorly designed and constructed structures have in many cases led to increased erosion.

Dredging

In addition to the loss of sediment from the placement of shore structures, dredging activities have also had an effect on the sediment supply to Lake Erie. Dredging involves the removal of sediment from shipping and recreational boating channels to increase navigation depths for larger commercial vessels. The material dredged is often placed offshore or in facilities closer to shore, known as confined disposal facilities (CDF). The placement of the sediment in the open lake or in a CDF depends on the level of contaminants that are contained within the sediment. When material is placed within a CDF it is usually left in place and capped with clean fill, creating an island or peninsula along the coast. These are common along the Toledo and Cleveland lakefronts.

The disposal of dredged material offshore and within a CDF results in the loss of sediment from the littoral system, limiting the supply of beach building materials. Since armoring the coast limits direct land-based inputs of sediment, and dredging removes riverine sediment, it is evident why beaches have continued to decrease along Ohio’s coast. Without the constant addition of sediment from either land or rivers, beaches will continue to decrease in size.

Lake Level Fluctuations

Lake level fluctuations in the magnitude of several inches to several feet are common within the Great Lakes. Short-term fluctuations, on the time scale of hourly to daily, are often caused by winds or barometric pressure changes. In Lake Erie the most dramatic of these changes is called a seiche. A seiche occurs mainly due to sustained winds in one direction over an extended period of time typically during a storm. As the wind pushes the water in one direction, the lake levels rise in the direction of the wind; this is referred to as wind set-up. The opposite end of the lake experiences decreased water levels. When the wind subsides, the water moves from one end of the lake to other. The lake levels may not return to normal until after a few of these back-and-forth cycles which may take several hours or more.

Seasonal fluctuations in lake levels also affect the all of the Great Lakes. In general, lake levels are their lowest in the winter months and peak in the summer. During the cool dry months of the fall and early winter, water from the warmer lakes evaporates, decreasing water levels. Once the lake temperature drops in the winter less evaporation occurs. Additionally, if the lakes freeze, the water levels remain relatively constant with minimal evaporation or precipitation.

In the spring, the runoff from snow melt adds water to the lakes. From the spring into early summer, the lake temperatures remain cooler than the air temperatures leading to condensation of moisture in the air. In the summer months, the air and water temperatures are closer and little condensation or evaporation occurs. This is when lake levels are once again relatively constant. The difference in the winter low lake levels compared to the high lake levels of summer months can be in the magnitude of a foot or more.

Longer-term changes to lake levels are more often caused by changes to multi-year precipitation rates and temperatures. For instance, several years of relatively warm weather with less than average precipitation will cause the lake levels to drop. The warm, dry weather cause greater levels of evaporation without adequate precipitation to replenish the lakes. The opposite scenario, with cooler weather and increased precipitation, causes lake levels to rise. This is due to more water entering the lakes and less being evaporated.

One of the more recent issues with long-term lake level fluctuations involves climate change. Current predictions indicate a lowering of the Great Lakes, mainly caused by warmer drier weather within the region.

Overall, the changes to lake levels in both the short-term and long-term can have an impact on erosion rates and associated mitigation techniques. During periods of low lake levels, erosion will increase within the nearshore environment, due to lakebed downcutting. This will cause significant erosion in areas that are otherwise unprotected. Existing shore structures may also be at risk of toe failure as lower water levels may cause waves to break at the structure toe, resulting in undermining of the structure. During times of higher lake levels, the bluff and shore will be at greater risk of erosion as waves will break closer to or on the shore.

Ohio’s Physical Coastal Features

Glacial Influence

The present day geologic features of Ohio’s coast were influenced by the passage of a series of glaciers that once covered the Great Lakes region. Several times glaciers advanced (moved south over the current landmass of Ohio and neighboring states) and retreated over millions of years, eventually creating the current Lake Erie basin and the familiar landforms along the coast. During the advance of the glaciers, ice scoured the land, whether soil or bedrock. This process transported materials from northern locations to areas south and deposited materials as the glaciers retreated. Each glacial cycle of advance and retreat repeated the removal and deposition process with younger layers placed on top of the previous glacier’s deposits.

In-between the periods of glacial coverage, there were often lakes covering portions of the current Lake Erie Basin. These interglacial lakes were responsible for the erosion and deposition sediment within portions of Ohio, similar to the way sediment is currently eroded or deposited within Lake Erie. The muddy or fine-grained sediments deposited on the lakebeds of the interglacial lakes are often referred to as glaciolacustrine, or glacial lake sediments. These glaciolacustrine sediments can be found within bluffs along the shore of Lake Erie.

After the advance and retreat of the last glacier, Ohio’s Lake Erie shore has remained relatively constant in terms of geological composition. The deposits from thousands of years ago still define the coastal geology of Ohio.

Present Day

The physical characteristics of Ohio’s coast vary significantly, ranging from the western lowlands to the imposing bluffs in the east. This variability is one of the main reasons erosion mitigation is challenging to address within the state; there is no single issue and therefore no one solution. In order to better control erosion, there should first be a clear understanding of the coastal setting and processes affecting Ohio. The following overview of Ohio’s coast will begin at the western end of the Lake proceeding eastward to the Pennsylvania state line. General coastal characteristics, natural breaks in relief, prominent features, significant habitat components, and key species will be identified and explored within this section.

There are three distinguishable basins recognized within Lake Erie - Western, Central, and Eastern. The basins increase in depth moving from west to east along the long axis of the lake. The Western Basin encompasses the area between Michigan’s Lake Erie coast and a hypothetical line that runs from Pelee Point, Ontario to Cedar Point in the city of Sandusky(9). The central basin is bound by the Pelee Point-Cedar Point line in the west and another line that runs between Long Point, Ontario and Presque Isle, Pa., on the east. The eastern basin is the area east of the Long Point-Presque Isle line to Buffalo, N.Y. Since the eastern basin does not include land within Ohio, it is beyond the scope of the LESEMP. The Western and Central basins, however aid in distinguishing the low-lying coastal regions of the west from the moderate-to-high banks or bluffs of the central Lake Erie shore. These basins will also be useful in identifying key species and their relations to nearshore habitat within each region.

Beaches

The presence of beaches is beneficial primarily in terms of hazards protection. Beaches are a natural barrier between the lake and upland properties. Where significant investments in houses and commercial ventures exist, beaches can limit the destruction from storms, as well as reduce the potential for persistent erosion and inundation.

Due to their ephemeral/transitory/changing nature, quantifying beaches is often difficult, but it is possible to estimate the areas where beaches are typically found through the use of GIS products. Based on data and images from 2006, it is estimated that roughly 26.5% percent of the length of Ohio’s coast is comprised of beaches. This linear figure does not account for the area (length multiplied by width) of the beaches, which is a better predictor of the protective potential of the beach. Additionally, since these features are always changing, the location, size and composition of the beaches in 2006 would be different from those today or those in the future.

Western Basin

Physical Setting- Shore, Nearshore and Offshore

Wetlands, barrier beaches, lake plains and low bluffs characterize the Western Basin of Lake Erie. This region has three main types of sediment- glaciolacustrine deposits, unconsolidated sand, and till. Bedrock within this area consists of limestone and dolomite, which is exposed in the Catawba Island area of the mainland and along the islands. Containing mainly low-lying coastal features, this region may be inundated during periods of higher lake levels and during moderate to extreme storm events.

The Western Basin contains two north-south oriented island chains. The western chain most notably includes the South, Middle, and North Bass Islands, while the eastern archipelago includes Kelleys Island and Pelee Island, Ontario. These features are comprised of limestone and dolomite bedrock, and are therefore more resistant to erosion than softer materials. The slow erosion rates of the island chains and their location at the interchange of the Western and Central basins has a strong influence on sediment fluctuations in this area. As sediment moves through the island region it is detoured in various directions around the more resistant portions of the islands and headlands of the mainland.

Gentle nearshore slopes are characteristic of the Western Basin. Within 2,000 feet of the shore the nearshore slope is generally less than one degree. The nearshore zone is mainly comprised of sand and gravel. Farther offshore, rock, till, till lag, glaciolacutrine clay, and silt can be found.

In general, the bottom (offshore) deposits of Lake Erie consist of a high proportion of mud. According to a study by Verber (1957), mud constitutes 58 percent of the bottom sediments in the Western Basin. The remainder of the deposits are: sand (17 percent), mud and sand mixture (12 percent), sand, gravel and coarser material (7 percent), hard clay (3 percent), and limestone and dolomite (3 percent).

Biological and Ecological Setting

The Western Basin biological community is influenced by several physical and chemical factors. The Detroit River connecting channel and Maumee River provide sediment and nutrient inputs to the western basin. These inputs form the basis of the Western Basin food web; however, suspended sediments and algal blooms caused by excessive nutrients can reduce light availability for plant growth. Sedimentation can also reduce hatching success for the eggs of some fish.

As mentioned previously, sediments in the Western Basin are dominated by mud and silt. These soft sediments host a variety of invertebrates, including mayflies. Larval mayflies burrow in the sediments of the western basin until they reach adulthood. They then migrate to the water’s surface, where they molt and take flight to spend the next 1-3 days reproducing.

Coastal wetlands historically dominated the shores of the Western Basin, providing unique habitats for fish and birds. Nearshore fish communities consisted of species that relied on these wetlands as spawning and nursery areas and included northern pike, muskellunge, largemouth bass, bluegills, crappies and bowfin. Shorebirds and waterfowl also use these habitats for feeding, nesting, and rearing their offspring. Following human settlement, lake access to most coastal wetlands was restricted or eliminated through the construction of dikes, levees and other water control structures. These changes to the coast have significantly reduced nearshore fish communities. Currently, the nearshore fish community is present only in a few remaining areas, such as East Harbor in Ottawa County and the protected bays of the Bass Islands, where aquatic vegetation is still available. Similarly, smallmouth bass are common around the gravel and cobble substrates of the Western Basin reef complex and islands.

Central Basin

Physical Setting: Shore, Nearshore and Offshore

At the border of the Western and Central basins is the Cedar Point sand spit. Due to higher sediment levels and a westerly flowing littoral current, the sand spit naturally formed in this location. Eventually, structures were placed along the lakeward edge of the sand spit to halt movement and prevent breaching, keeping the feature in its current location. The area landward of the Cedar Point sand spit is relatively low-lying, including some wetlands. East of Huron, however, the physical relief begins to increase with moderate bank/bluff heights. Bluff heights increase from west to east and can range anywhere from 15-feet up to 50-feet in parts of Lorain County. Although shale bluffs are a distinctive feature of the shore in and near Vermilion, for the most part, these bluffs are comprised of glaciolacustrine deposits capped with till.

Near Avon Lake, the bluff composition begins to change from glaciolacustrine deposits to shale bluffs. This area of composition change is a significant feature along the coast, easily identifiable by the headland known as Avon Point. The shale bluff composition continues eastward until approximately Cleveland Harbor, at which point the relief decreases significantly due to the presence of the Cuyahoga River valley. Harbor structures and the placement of artificial fill have created a part of the coast that is relatively non-erosive, with the original bluffs hundreds of feet landward of the shore.

From Cleveland Harbor eastward, bluff heights range from 20 to 65 feet, with the greatest relief found in Ohio’s easternmost county of Ashtabula. With exception to some anomalous features, such as river valleys, the physical relief of this area generally increases from west to east. There are also areas within Lake County of higher relief but gradual bluff slopes, causing a slight variation in the erosive events at these locations. This eastern section of the Ohio coast is generally comprised of glaciolacustrine deposits and till.

The nearshore slopes within the central basin are relatively gradual out to approximately 2,000 feet. Once offshore, the central basin has depths averaging 60 feet whereas the western basin only averages depths of around 30 feet.

Similar to the offshore deposits of the Western Basin, the Central Basin consists of mainly mud. In the Central Basin, silt and clay mud comprise 76.6 percent of the bottom deposits, with sand and gravel 22.5 percent, and shale bedrock 0.9 percent, making up the remainder. Closer to shore, till and pebble lag deposits have been noted, but are not in significant enough amounts to be quantified.

Biological and Ecological Setting

The nearshore area of the central basin is influenced by the higher relief, firmer sediments and deeper, cooler water in the region. With the exception of some river mouths and protected harbors, aquatic vegetation is not common along the central basin shore. Instead, nearshore habitat consists of scattered cobble and boulders that favor species like smallmouth bass and gobies. Offshore, the fish community is dominated by pelagic species such as walleye, white bass, gizzard shad, emerald shiners, and rainbow smelt, or by benthic species such as yellow perch, gobies, and burbot. Mayflies are also present in the central basin.

Western Basin processes affect habitat in the Central Basin. As water leaves the Western Basin, it carries with it organic material and nutrients that are deposited on the sediments of the central basin. Bacterial activity increases in order to break down this influx, creating an area of water near the sediments with low dissolved oxygen levels. This large oxygen-depleted area is known as the ‘dead zone,’ and forms each summer in the Central Basin offshore. The dead zone, which typically extends only a few feet above the sediments, forces many fish and invertebrates to relocate above or outside the oxygen depleted area. Oxygen depletion in the offshore can impact the biological community in the Central Basin nearshore. When strong seiches push the oxygen rich top layer of the water column away from shore, anoxic water from the dead zone is pulled inshore. Minor fish kills following summer storms have been attributed to these events.

References:

1. Ohio Rev. Code § 1506.47 (current through 128th General Assembly).
2. Gould, William H. Lake Erie Beach Erosion Studies, First Annual Report. U.S. Beach Erosion Board, State of Ohio, Department of Public Works, Erosion Division. July 31, 1940.
3. State of Ohio, Department of Natural Resources Division of Shore Erosion Master Plan, (undated).
4. Keillor, Phillip and Elizabeth White. Living on the Coast: Protecting Investments in Shore Property on the Great Lakes. U.S. Army Corps of Engineers and University of Wisconsin, 2003.
5. Cross, Marlene, Mike Campbell, and Marti Martz. Vegetative Best Management Practices: A Manual for Pennsylvania/Lake Erie Bluff Landowners. Pennsylvania Sea Grant (undated). http://seagrant.psu.edu/publications/erosion.htm.
6. Chase, Ronald et al. Stabilizing Coastal Slopes on the Great Lakes. University of Wisconsin Sea Grant Institute, undated. www.aqua.wisc.edu/piblications.
7. Barnes, Peter W., Michael McCormick, and Donald Guy. Open File Report93-539: Winter Coastal Observations, Lake Erie, Ohio Shore. U.S. Department of Interior, U.S. Geological Survey. (undated).
8. State of Ohio, Department of Natural Resources, Office of Coastal Management. Ohio Coastal Atlas, Second Edition, 2007.
9. State of Ohio, Department of Natural Resources, Division of Geological Survey. A Preliminary Report on Currents and Water Masses in Lake Erie. Presented to the Ohio Pollution Control Board. 1966.
10. Carter, C.H., D.J. Benson, and D.E. Guy. “Shore Protection Structures: Effects on Recession Rates and Beaches From the 1870s to 1970s Along the Ohio Shore of Lake Erie”. Environ Geol: 3 (1981): 353-362.
11. Hartley, Robert P. Report of Investigation No. 53: Effects of Large Structures on the Ohio Shore of Lake Erie. State of Ohio, Department of Natural Resources, Division of Geological Survey. 1964.
12. Gauthier, Roger and Michael J. Donahue (Eds.). Living with the Lakes. U.S. Army Corps of Engineers and Great Lakes Commission. Second printing, 2000.
13. Benson, D. Joe. Report of Investigations No. 107: Lake Erie Shore Erosion and Flooding, Lucas County, Ohio. State of Ohio, Department of Natural Resources, Division of Geological Survey. Columbus, 1978.
14. Benson, D. Joe. Draft, Open-File Report 96-xxx: Lake Erie Shore Erosion and Flooding, Ottawa County, Ohio. State of Ohio, Department of Natural Resources, Division of Geological Survey. (undated).
15. Carter, Charles H. and Donald E Guy. Report of Investigations No. 115, Lake Erie Shore Erosion, Erie and Sandusky Counties, Ohio: Setting, Processes, and Recession Rates from 1876 to 1973. State of Ohio, Department of Natural Resources, Division of Geological Survey, Columbus, 1980.
16. Benson, D. Joe. Draft, Open-File Report 96-xxx: Lake Erie Shore Erosion and Flooding, Lorain County, Ohio. State of Ohio, Department of Natural Resources, Division of Geological Survey. (undated).
17. Guy, Donald, D.J. Benson and C. H. Carter. Draft, Open-File Report 96-xxx: Lake Erie Shore Erosion and Flooding, Cuyahoga County, Ohio. State of Ohio, Department of Natural Resources, Division of Geological Survey. (undated).
18. Carter, Charles H. Report of Investigations No.99: Lake Erie Shore Erosion, Lake County, Ohio: Setting, Processes, and Recession Rates from 1876 to 1973. State of Ohio, Department of Natural Resources, Division of Geological Survey. Columbus, 1976.
19. Carter, Charles H. and Donald E Guy. Report of Investigations No. 122, Lake Erie Shore Erosion, Ashtabula County, Ohio: Setting, Processes, and Recession Rates from 1876 to 1973. State of Ohio, Department of Natural Resources, Division of Geological Survey, Columbus, 1983.
20. Bolsenga, Stanley J. and Charles E. Herdendorf (Eds.), Lake Erie and Lake St. Clair: Handbook. Wayne State University Press, Detroit, MI 1993.
21. Lake Erie Beach Erosion Studies, U.S. Beach Erosion Board, State of Ohio, First Annual Report, Erosion Division, William H. Gould, Department of Public Works, July 31, 1940.

Chapters to Follow

The information contained in this chapter provides information about the general characteristics of Ohio’s 312-mile Lake Erie coast. Additional LESEMP chapters contain more detailed information—each about a specific region of Ohio’s coast. Specifically, the coastal geology, nearshore habitat and erosion processes of each region are characterized. A set of recommendations is included in each chapter based on the characteristics of the reach and on information collected from property owners and public officials. The chapters, and each reach within each chapter, can be read separately or as a piece of the larger document.

While there names are subject to change, as of 12/16/2011, the Chapters within the LESEMP are named as follows:

• Chapter 1 Introduction Webpage
  
• Chapter 2 Maumee Bay (MB) Webpage
  
• Chapter 3 Western Basin (WB) Webpage
  
• Chapter 4 Limestone Outcropping to Johnson’s Island including Lake Erie Islands (MP) Webpage
  
• Chapter 5 Sandusky Bay (SB) Webpage
  
• Chapter 6 Cedar Point to Vermilion River (CV) Webpage
  
• Chapter 7 Vermilion River to Lorain/Cuyahoga County Line (LC) Webpage
  
• Chapter 8 Lorain/Cuyahoga County Line to Cleveland Harbor (WS) Webpage
  
• Chapter 9 Cleveland Harbor (CH) Webpage
  
• Chapter 10 Bratenahl to Grand River (BG) Webpage
  
• Chapter 11 Grand River to Lake County Line (EL) Webpage
  
• Chapter 12 Ashtabula County (AC) Webpage
  
• Appendix: Erosion Control Methods Webpage | factsheet
  
• Glossary Webpage | factsheet
  

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