We're turning back the clock on behalf of nature.
Many years ago, western Kentucky's wetlands formed an intact floodplain around the Mississippi River. During flood events, the excess water flowed into the surrounding land, where it was stored and slowly returned to the river. Sediments and other pollution were captured in the wetlands as the water meandered back to the Mississippi, resulting in cleaner water.
Human Impacts on Wetlands
Great change occurred when people drained the land for agriculture and development.. Trees were cut down. Ditches and levees were installed. Streams were straightened, deepened, and widened.
This new “plumbing” resulted in water running off of the land quickly, taking pollution and sediment along with it. The cumulative result throughout the Mississippi River Basin has been degraded water quality in both local streams and large rivers, and ultimately the formation of a large “dead zone” in the Gulf of Mexico.
Wetland restoration involves taking frequently flooded cropland out of production,, re-planting trees, and changing the way the water moves across the land to act like a natural wetland system again. Trees are selected based on the soil type and flooding frequency of the wetland,, and are usually mast-producing trees planted at 435 seedlings per acre. It takes a decade or more to establish a young forest after these plantings.
Restoring the hydrology of the area may include plugging ditches that were previously installed to drain the land. Occasionally a levee may be installed. In either case, the result is that water stays on the land longer. When the land is capable of absorbing and holding water longer, it is able to remove nutrient pollution, which leads to improved water quality at the local level as well as downstream in large rivers and the Gulf of Mexico.
Monitoring Our Progress
A five-year, $4.36 million study funded by the Natural Resources Conservation Service (NRCS) will monitor the wildlife benefits and water-quality effects of wetland restoration in western Kentucky. Launched in June 2018, the study is being led by NRCS and The Nature Conservancy. Murray State University will implement the monitoring work.
“We work with farmers to take frequently flooded land out of agricultural production, plant native trees in the area, and where possible, restore the hydrology,” says Shelly Morris, TNC’s western Kentucky project director. “In some cases, we plug ditches that were installed decades ago to drain the land or install levees to retain water seasonally. After all this work, we want to know the impact we’re having on reducing nutrient pollution.”
According to Morris, an intact floodplain holds water after a flood event and slowly lets it drain back to the river. Many wetlands within the Mississippi River floodplain, however, have been ditched and cleared to allow for farming and development. As a result, water quickly runs off the land, taking excess nitrogen, phosphorus, and sediments into the river. This nutrient pollution makes its way down the river all the way to the Gulf of Mexico, where it contributes to a dead zone – a low oxygen zone nearly devoid of life – that is now the size of New Jersey.
Conservation organizations have worked for years to restore wetlands so the land can hold water longer, reducing the nutrient pollution going into the Mississippi River.
“We are excited about this project, not only because we are breaking new ground in terms of restoration monitoring, but because our results will aid the planning of future restoration efforts here in Kentucky and throughout the Mississippi River basin,” said Howard Whiteman, a professor in Murray State University’s biological sciences department and director of the Watershed Studies Institute.
The monitoring project will study the restored wetlands’ potential to reduce nutrient pollution and will measure water and soil quality. Murray State University will also look at the wildlife impacts of these restoration efforts. Clarifying the effects of restoration will help conservation groups conduct better restoration in the future and may help secure funding for future projects.