The southern basin of Lake Michigan began to form approximately 12,000 years ago.¹ The beginnings of Indiana's Lake Michigan coastline have transformed over time to the south shore of present day, and continue to change in response to the climatic influences in the Great Lakes region. These changes often impact our human desire to live, work, and recreate near this dynamic coastline.

As Lake Michigan formed by the advance and retreat of glaciers, dunes and beach systems formed at the southern end. A large ice sheet extended just south of the present Lake Michigan basin which acted as a dam helping to form what became Ancient Lake Chicago, a reservoir to hold melt water from the glacier. Along the southern and eastern shores of Lake Chicago, the formation of dunes occurred which today are known as Glenwood Dunes. During this stage, the lake-level was approximately 50-60 feet higher than it is today. As the glacier retreated north, Lake Chicago swelled and the Calumet Dunes were formed. Lake levels continued to fluctuate up to 30 feet above present day level to 60 feet below present day level. The dunes present on the Indiana shoreline today are estimated to be 2000 to 3000 years old.²


Fluctuation of Great Lakes Lake Levels

Lake level fluctuations continue to occur in the Great Lakes. The level of each of the Great Lakes, including Lake Michigan, depends on the balance between the quantities of water received and the quantities of water removed. As the supply of water changes under natural outlet conditions in a lake, the lake-level and outflow adjust continually to restore a balance between the net supply of water to the lake and the outflow through its outlet. Lake levels affect extent of flooding, shoreline erosion and shoreline property damage, wetland acreage, depth of navigation channels, and hydroelectric power output.³

Lake level records have been kept for Lake Michigan and Lake Huron since 1860, at Harbor Beach, Michigan. The lowest monthly average lake level recorded during that time, 575.35 feet International Great Lakes Datum (IGLD) 1955 (576.05 IGLD 1985), occurred in March 1964. The highest monthly average lake level recorded 581.94 feet IGLD 1955 (582.64 IGLD 1985) occurred in June 1886. This is a difference of 6.59 feet in water level since records have been kept. The most recent high lake level recorded for this century was in October 1986 at 582.35 feet (IGLD 1985).

In January 1995, Lake Michigan was slightly more than seven inches above the "long term monthly average" level (1918 to present), but the lake level gradually fell over the next seven months. During the last four months of 1995, lake levels were approximately the same as each month's "long term average." In February 1996, lake levels began to rise slowly, and between April and May the lake began a rapid rising trend. By August 1996 Lake Michigan had risen one and one-half feet since January. Lake Michigan lake level decreased only three inches by December 1996 leaving the lake level in December one foot three inches above December's long term average. Between January 1997 and July 1997 lake elevation went up 16 inches, but decreased 16 inches by December 1997. Although still above the December long-term average by one foot three inches, the present trend seems to be a decline in lake level due to lower than average precipitation. A graph of Lake Michigan water levels can be found on the Lake Michigan Coastal Coordination Program homepage.

Several studies have been commissioned to research the prevention of damage to the shoreline of Lake Michigan and other Great Lakes due to drastic changes in lake levels. As a result of high water levels occurring in 1950, the U.S. House of Representatives requested that the U.S. Army Corps of Engineers determine the feasibility of measures to prevent recurrence of damages. The study provided information on various lake-regulation plans and associated costs.
Again, in the early 1970s, extremely high lake levels generated concern. The International Great Lakes Levels Board presented a report to the International Joint Commission in 1973 concerning potential changes in lake-level regulation plans at existing regulatory sites on the lakes as a means of alleviating problems caused by high lake levels. The Board found that only small improvements are practicable without costly regulatory works and remedial measures. The Board also concluded that the most promising measures for minimizing future damages to the shore property are strict land-use zoning and structural setback requirements.⁴

Record high lake levels, occurring again in 1985 and 1986, resulted in a series of studies and publications concerning Great Lakes water levels. An overview of lake levels was provided in A. Bixby, GREAT LAKES WATER LEVELS - AN OVERVIEW: THE CENTER FOR GREAT LAKES, CHICAGO, ILLINOIS (1985). In 1984, the U.S. Army Corps of Engineers developed a publication on Great Lakes water level facts. Briefings were held in 1985 by the Corps and the International Joint Commission with Senators and representatives of the Great Lakes basin states concerning water levels of the lakes. The Great Lakes Commission published a report in 1986 concerning water level changes and factors influencing the Great Lakes.

A recent investigation has been undertaken by the International Joint Commission at the request of the United States and Canadian governments to re-examine and report on methods of alleviating the adverse consequences of fluctuating water levels in the Great Lakes-St. Lawrence River Basin using the most up-to-date techniques and information. Phase II of the International Great Lakes Level Board investigation was completed in 1989. Phase II was completed in 1993.

The major conclusions reached in the Phase I report are that: 1) the Great Lakes water level fluctuation situation must be approached on a system-wide basis; 2) that specific measures aimed at affecting system-wide water level fluctuations are probably futile; 3) and that there must be a recognition of need for a fundamental change in the conventional approach to alleviating adverse consequences. Phase II documents include information on the following topics: 1) key results of technical studies; 2) guiding principles for governments; 3) measures to reduce impacts of fluctuating water levels; 4) emergency actions in response to crisis conditions; 5) institutional arrangements; and 6) communications practices.

In the mid 1970s and 1980s, high lake levels led to severe erosion and flood conditions along Indiana's shoreline. Lake levels reached over three feet above the "long term average" in October 1986.⁵ Damage was reported by most shoreline communities. Roughly $867,526.00 in damages were reported by the Indiana Department of Civil Defense (now the Indiana State Emergency Management Agency) for the 6.5 miles of shoreline in LaPorte County.⁶


Coastal Erosion

In addition to the natural process of the fluctuation of lake levels is the natural process of the transport of sediment, or sand, along the coastline. The waves and currents which transport this sand are driven by wind.⁷ The intensity of storms on Lake Michigan plays a primary role in determining the amount of erosion that occurs in any given year.⁸ Without storms, there would be no waves or currents to move large quantities of sand along the beach and lake bottom. Lake level affects whether waves attack low on the beach face when lake levels are low, or waves attack high on the back beach at the base of the erodible dune-bluff, when lake levels are high.

Storm winds generate waves by transferring some of the wind energy to the surface of Lake Michigan. The wind energy is stored in the form of waves moving across the lake surface. Waves grow bigger as more wind energy is added. Out in deep water, very little wave energy is lost from waves as they move from one side of the lake to the other. But, when the waves reach shallow water at the coast, the stored wave energy is converted into "breaking waves" and "water currents" capable of eroding and moving sand.⁹

The strongest and fastest currents found in Lake Michigan are concentrated around the edge of the lake in a narrow "breaking wave zone," starting in water depths between 18 to 20 feet deep and extending to the beach. This zone is also the location of the greatest volume of sand transport (littoral drift).

If wave crests approach the coast parallel to the beach, sand movement is primarily onshore and offshore. But, when waves approach the coast at an angle, water currents move along shore and can carry sand in the direction the storm waves are moving. The amount of sand that moves depends on sand availability, the size of the waves and the length of time the waves are present to drive the water currents in one direction.

The "net" direction of sediment movement is the direction that the largest volume of sand moves over a given period of time. If a small amount of sand moves east during the first part of a storm, but more sand moves west during the latter part of the same storm, the net direction of sand movement would be toward the west. If this pattern persists storm after storm, a net direction of sediment movement is established for that part of the coastline.¹⁰

From the Michigan state line to Gary, Indiana, the net direction of sand movement (littoral drift) along Indiana's coast is from the east toward the west. But, from the Illinois state line to Gary, Indiana, the net direction of sand movement is from the west toward the east. These opposite directions of net sediment movement is expected, due to two determining factors.

The first factor is that the most powerful storm waves approach both portions of Indiana's coast from the north, since the strongest storm winds blow out of the northwest, north, and northeast directions. These winds are able to transfer considerable energy into waves coming from the north because there is approximately 300 miles of open water between the north end of Lake Michigan and the Indiana coastline.

The second factor actually responsible for the opposite net directions of sand movement, east and west of Gary, is the different orientation of the shorelines. Since Gary is located at the southern-most tip of Lake Michigan, the shoreline east of Gary is oriented in a northeast by southwest direction. The shoreline west of Gary is oriented in a northwest by southeast direction. As storm waves approach from the north, the different orientation of the shorelines results in both currents flowing toward Gary, Indiana.

In order to plan for coastal development and protection of the shoreline¹¹, long term records covering both types of erosion conditions are needed for a reasonable estimate of the "background" erosion rates that can be expected for a particular portion of the shoreline. Erosion rates typically vary from high erosion to low erosion periods, determined by climatic "storminess," long term changes in "lake level," and the influence of sand availability due to man-made structures. Some years may see high erosion because of a combination of severe storm events, high lake level, and severe sand starved conditions. Some years may see low erosion because of mild storms, low lake levels and abundantly wide sand beaches. Averaging the episodes of high and low erosion should provide a fairly good estimate of "long term erosion rates" to allow a fairly accurate estimate of future erosion. The average background erosion rate for the Great Lakes is three feet annually, but the rate may also vary considerably by locality. For example, the average background erosion rate for Mount Baldy at Michigan City, Indiana is about ten feet annually.¹²


High Erosion Hazard Areas

A High Erosion Hazard Area (HEHA) is a portion of the shoreline with a long term erosion rate greater than one foot per year. The Indiana shoreline of Lake Michigan includes several HEHAs; however, many of the areas are currently protected from erosion by man-made structures or are included in the national or state park where the natural shoreline is preserved.¹³

High Erosion Hazard Areas in LaPorte County include areas located in Michiana Shores and Long Beach east of Michigan City. However, this portion of the shoreline has been protected by rock revetment in order to protect Lake Shore Drive and seawalls constructed by private homeowners. West of Michigan City portions of the shoreline are owned by the National Lakeshore. Areas such as Crescent Dune and Mount Baldy are intended to remain as natural shoreline. Here, nonstructural methods of controlling erosion (beach nourishment) have been used in 1974, 1981, 1996, 1997, and 1998.

Further west on the coast in Porter County, a HEHA is identified on property owned by the Indiana Dunes State Park. However, this area is also maintained as natural shoreline. A short length of property fronting the Town of Porter is designated a HEHA. Although all of the shoreline owned by the Town of Dune Acres is a HEHA, only a minimal area is left unprotected by hard structures. Just less than one mile of shoreline west of the Burns Small Boat Harbor is considered a HEHA, but most of this area is protected by the Harbor breakwater, is owned by the National Lakeshore, or is protected by erosion protection structures built by private property owners in Ogden Dunes. In 1997, the eastern most homes were further protected by a new seawall built by the State of Indiana.

Very little of the shoreline in Lake County is designated as a HEHA. This circumstance is largely attributable to the extensive erosion protection structures constructed by industries along the shoreline. Evaluations regarding erosion potential are not feasible in these areas. The eastern most area of the Lake County shoreline near Wells Street Beach is designated as a HEHA. The only other location along the shore in Lake County which could be evaluated for erosion potential was Whihala Park Beach in Whiting.

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