The Great Marsh

The Great Marsh Historical Geology

The most recent chapter in the geologic story of the Great Marsh is that of the modern landscape as it appeared to the first European explorers who arrived in the Little River Valley and its subsequent modification to make way for agriculture and urban development over the ensuing centuries. Of necessity, this part of the story takes place at the intersection of geology, ecology, and human history.

The hydrological aspect plays a central role in both the ecology of the Great Marsh and in the patterns of human settlement and use of the region. The map of the upper Little River Valley shows some of the key aspects of this relationship, depicting the main geological elements in and around the valley, along with major ecological and historical features through time.

The Wabash Valley was a key travel and trade route for both the early explorers and for Native Americans. The ability to navigate the Little River within striking distance of the St. Marys River was crucial to the success of the route, and ultimately led to Fort Wayne becoming established as the ‘Summit City’ along the portage between the two drainages, a somewhat ironic term

Picture courtesy of Hasselblad, 2024

since the ‘summit’ it refers to actually is only a few feet above the lowest elevation in the whole regional landscape!

The Miami in the Little River Valley

Long before and well into the 1800s, the Miami Nation navigated the waterways of the Little River Valley, using their deep knowledge of the land’s geology. While Kekionga is widely known as a Native trade hub, two lesser-known sites also reveal the Miami’s strategic use of the landscape.

One is the south channel of the valley, which may have served as an alternative canoe route between the St. Marys River and the Little River. The nearby Pinšewa (Richardville) House and the Miami’s land selections suggest its importance. Richardville reportedly built a small dam to raise water levels, making nearly continuous travel possible with only a short portage near present-day Ardmore Road.

The second site, known as “The Cranberry,” is a wetland area at the northern edge of the watershed, straddling the continental divide. Chief Lagro requested land near it, likely due to its resources and significance. The Cranberry preserves rare wetland habitats but faces growing pressure from development.

Together, these places reflect the Miami’s long-standing relationship with the land and its natural waterways.

Early Hydrologists

When explorers ventured up the Wabash River from western Indiana in the early 1700’s, they encountered a vast marsh that covered virtually the entire floor of the Little River Valley between Huntington and Fort Wayne. The marshy expanse was broken only by a few, small wooded dunes, or islands. In time, this wetland became known as the “Great Marsh,” and while it presented a major impediment to settlement, it also acted as a navigable waterway of great strategic value, to early settlers, traders, and the Native Americans of the region; the Miami Nation widely utilized the Little River Valley as a source of fish and game, for travel, and for its strategic value.

In all but the driest times, it was feasible to canoe up the river from the forks of the Wabash to a position just northwest of Fox Island. From there, the portage followed the slightly drier terrain along the northern edge of the valley to the St. Marys River. Some accounts also describe the ability to canoe all the way to the St. Marys during wet periods that typically occurred between late winter and early summer, whereas other less fortunate travelers sometimes had to portage the entire 24 miles when making the trip during the dry late summer and fall months. These early accounts are the first to suggest the seasonal hydrology of the Great Marsh. The continental divide near the east end of the portage later became the high point along the Wabash & Erie Canal or the ‘summit.’

Hydrology of the Great Marsh Ecosystem

This map attempts to reconstruct the Little River Valley marsh and the continental divide as they may have appeared when Europeans first arrived. Using historical records, topographic data, and aerial imagery, the original stream channels and tributaries feeding the Little River are depicted, though some details remain speculative due to the valley’s complex history of shifting waterways. These slowly migrating channels shaped the ecosystem, forming narrow open-water ribbons that supported diverse aquatic life and bird species. Surrounding these were true marshes and wet prairies, their exact placement determined by slight elevation changes. Scattered throughout the marsh were elevated sand dunes, which hosted entirely different hardwood forest ecosystems rich in biodiversity.

Water feeding the marsh came from several sources: rainfall, upland tributaries, and major flood events. The Little River itself originated in northern Wells County and entered the valley near present-day Ardmore Road, depositing sediments where the land flattened. Cranberry Creek, now called Graham-McCullough Ditch, entered from the north near Eagle Marsh. Occasionally, massive floods from the St. Marys River spilled over the low divide at the north channel’s head, dramatically increasing flow into the Little River Valley. The flood of 1913 is a documented example, when an estimated 5,000 cubic feet per second poured into the valley, significantly reducing peak flood levels downstream.

In addition to surface water, groundwater also played a major role in sustaining the marsh. Discharge from local aquifers—formed by sand dunes, outwash fans, and terraces—emerged along valley edges, feeding fens and seepage swamps. This process is still visible today at places like Eagle Marsh Woods. Furthermore, buried aquifers beneath glacial deposits and limestone bedrock also contribute to the valley’s water supply. Altogether, the Little River Valley serves as a critical groundwater discharge zone for the surrounding region, supporting a diverse and dynamic wetland ecosystem.

The Draining of the Great Marsh

By the 1870s, Fort Wayne had grown into a sizable town, but the nearby Little River Valley, known then as the “Marshy Prairie”, remained largely undeveloped. Local agricultural interests began pushing for its drainage, and by the late 1870s, state legislation had cleared the way for major drainage projects. This effort was part of a broader statewide movement to convert wetlands into farmland, driven by new drainage laws that empowered local governments to take and alter private land at the owners’ expense.

By the late 1880s, most of the Great Marsh had been drained. Three major ditches were key to this transformation. Fairfield Ditch, completed by 1880, redirected the Little River’s headwaters into the St. Marys River, removing a major water source from the valley. Graham-McCullough Ditch, containing Cranberry Creek within a levee, cut off water and sediment flow to the marsh near Eagle Marsh. Junk Ditch, the most transformative, stitched together existing streams with new channels, diverting several square miles of land away from the Little River watershed and shifting the continental divide by up to three miles.

Following drainage, agriculture flourished in the valley’s rich soil. Moisture-loving crops like celery and lettuce thrived, and the area became known for celery production by the early 1900s. Yet persistent wetness remained a challenge, with draft animals sometimes sinking into the muck. After World War II, vegetable farms gave way to grain crops, and even advanced drainage systems often couldn’t prevent flooding and crop loss.

Ironically, modern farms in the valley now rely on irrigation systems that pump groundwater to water fields that once had too much water. Draining the land also had long-term consequences: as the rich organic soils dried out, they oxidized and eroded, gradually lowering the land surface and reducing soil fertility.

Restoration of the Great Marsh at Eagle Marsh

Ongoing difficulties with farming the wet soils of the Little River Valley, along with growing recognition of the ecological value of wetlands, have led to efforts to restore parts of the historic Great Marsh. A prime example is Eagle Marsh, one of Indiana’s largest wetland restoration projects. The goal is to recreate the marsh’s original bottomland ecosystems while adapting to a landscape now characterized by less surface water.

One of the main challenges is that ditches, roads, and channelized streams, like the Little River and Cranberry Creek, have cut off natural water flow. Because surface water rarely reaches the marsh, the restoration relies mostly on rainfall. Key restoration efforts include removing old drainage systems, reshaping the land to recreate natural basins, and using these depressions to hold water. These shallow, isolated pools provide crucial habitat for a wide range of wetland species and help recreate the marsh’s ecological functions.

Another complexity is understanding the marsh’s hydroperiod, or how long areas stay wet during the year. Different types of wetlands (like marshes, wet meadows, and wet prairies) depend on varying water levels and timing. Since historical data on the original marsh’s hydroperiod is limited and today’s conditions are drier and more variable, restoration efforts include planting resilient species. Prairie plants, which tolerate seasonal moisture swings, are heavily used. The project also includes a diverse seed mix to ensure that if some plants fail, others can thrive.

Ultimately, Eagle Marsh functions as a large-scale ecological experiment. It will take years to see how changing hydrology influences plant and animal communities, making the project a dynamic example of adaptive restoration in a modern, altered landscape.