Just as the face of Illinois grasslands has changed from native prairie to non-native pastures, golf courses, and hay fields, many of our state's original aquatic habitats have been replaced with human made substitutes. Marshes, temporary spring pools, swamps, and wet meadows have been replaced by fishing ponds, stormwater retention basins, and livestock watering holes. Many bodies of water exist in Illinois today, but they differ completely in size, depth, location, and biological character from our original wetlands.

When the pioneers arrived, they found the Illinois landscape dominated by vast expanses of tallgrass prairie interspersed with wet meadows and shallow water marshes. Settlers in southern Illinois and along the major rivers encountered forested wetlands. All of these "wet areas" were viewed as serious impediments to travel, agriculture, and human habitation. The wetlands also harbored disease, since they were reproduction sites for mosquitoes that carried malaria, referred to as "ague" by pioneers.

As Illinois was being settled, ditches and then field tiles were used to drain the wetlands. When possible, wetlands were filled in. Many rivers and streams were also channelized, straightened, or flanked with levees. The levees severed many bottomland swamps and marshes from their natural water supplies, causing them to dry up.

The result of these activities has been a net loss of about 90% of our state's natural wetlands. Human-created lakes and ponds have helped ease the loss of the natural wetlands, but because they have not been made by nature, their biological diversity is, in most cases, greatly diminished from that of the seven million acres of natural wetlands that have vanished from Illinois.

Three factors continue to exert a negative influence on Illinois aquatic habitats and the wildlife that depend on them:

Poor Quality

A number of factors contribute to the decreased quality of Illinois wetlands. Unbuffered runoff continues to deliver pollutants (sediment, chemicals, heavy metals, etc.) to many Illinois lakes, ponds, rivers, streams, marshes, and swamps. Pesticides have reduced numbers of plant and insect species, thus lessening food supplies for other wildlife. Sediment from croplands and construction sites is considered the number one threat to all types of wetlands. It muddies the water, creating an environment where many invertebrates cannot survive, thus diminishing life at the lower end of the food chain. Muddy water also makes it difficult for some aquatic predators-fish, amphibians, reptiles, and mammals-to see their prey. Murky conditions that limit sunlight retard or prevent the establishment and growth of many aquatic plants, which are needed both as food and as habitat for aquatic-dwelling animals.

The negative perceptions of wetlands held by many landowners and the resulting destruction of aquatic plants have also greatly reduced the quality of many of our wetlands. Most biologists define "quality" aquatic habitat as wetlands that support a full complement of interacting plants and animals. Plants provide food for wildlife, surfaces for invertebrates to attach to or lay eggs on, and cover for young fish and amphibians. And ironically, aquatic plants actually help make water clearer-a goal of many landowners. But many pond and lake owners like to see their water free of any aquatic plants, especially to aid fishing. Landowners who have created these fishing ponds have an opportunity to increase wetland diversity by encouraging more aquatic vegetation.

In some parts of Illinois, invasive exotic plant and animal species are destroying intact and productive wetland systems. Aggressive plant species such as the non-native purple loosestrife and the native common reed (phragmites) have created near-monocultures in some marshes, while the invasion of animals such as the grass carp and zebra mussel have reduced native species in various locations.

Changing Size and Interspersion

Fragmentation can be an issue with wetlands as it is with other habitat types. Certain wildlife, such as bitterns and some rails, need extensive acreages of cattail marsh to successfully reproduce. Large expanses of cattail marsh are uncommon in Illinois today.

Wetland complexes forming a mosaic of deep and shallow pools within an area were also once common in Illinois. Such mosaics allowed for great wildlife diversity because there was a more diverse food supply and a variety of places to seek cover and raise young. If one wetland dried up, others nearby would still hold water and provide the habitat needed by tadpoles, young wood ducks, or herons. Today, individual aquatic habitats are often small and isolated.

Another factor in interspersion of wetlands is their proximity to other quality wildlife habitat. Most borrow-pit lakes along interstate highways, for example, have little wildlife value. They are typically nothing more than bowls of water surrounded by intensively farmed cropland, with little or no adjacent natural vegetation. Many wildlife species need water next to woodlands or grasslands to fulfill their living requirements.

Decreasing Amounts

A surprising number of the few natural wetlands remaining in Illinois still have no permanent protective status and could thus be drained or filled. Federal wetland regulations have slowed the destruction of natural wetlands, but these habitats are still disappearing. Sedimentation and urban sprawl are currently the two primary causes of wetland loss.

Sediment continues to fill many floodplain and upland wetlands. Though sedimentation is a natural process, human activities have greatly increased the amount and frequency of deposition and have disturbed the natural hydrologic cycles that flush sediments out of some wetlands. In a natural setting, some wetlands fill in and disappear while new ones are carved out. In today's landscape, the land is carefully controlled, often preventing the development of new wetlands.

Urban sprawl continues to overrun small wetlands that many people consider worthless. While permits are usually necessary before wetlands can be eliminated, many requests are ultimately approved. Federal regulations allow this by a process known as mitigation. Rules do require new wetlands to be created to replace any approved for destruction, but it is very difficult to create new wetlands that provide the same benefits natural wetlands offer. Thus, protection of existing wetlands, rather than destruction and replacement through mitigation, should be a high priority for all landowners. In some cases, degradation of natural wetlands is substantial, and active management, including manipulation of vegetation and water levels, is essential to restore suitable habitat for wildlife.

Temporary, ephemeral, and intermittent wetlands are also being lost in Illinois. These terms describe areas that hold shallow water only temporarily or that contain water in some years but not others, depending on precipitation and water-table levels. Throughout our state's history many citizens have questioned the value of these wetlands. These temporary wetlands are some of the most easily destroyed. With the advent of modern drainage methods, thousands of ephemeral wetlands have disappeared with little notice.

These types of wetlands, however, are some of the most important components of the landscape. Semi-aquatic animals such as salamanders, certain frogs, and some toads depend on shallow, fishless water to deposit their egg masses. Historically, these amphibians' life cycles have followed the seasonal rains that formed thousands of temporary spring ponds in Illinois forests and grasslands. Now they face reduced breeding habitat statewide because of the reduction of wetlands, especially the temporary ones.

Ephemeral wetlands are also critical habitat for migrating birds. The shallow waters and associated mudflats provide a banquet of invertebrates for hordes of shorebirds and waterfowl that feed in these habitats. The massive amount of food produced in temporary wetlands and mudflats plays a significant role in the life cycles of these birds, allowing them to complete their journeys to breeding or wintering grounds in a healthy condition. Most Illinois landowners, though, do not recognize the importance of temporary wetlands and thus continue to destroy them.