Study links groundwater to stream, peatland health

Sep 29, 2021

From space, the Kenai Peninsula looks like it has a lot of water. After all, it’s surrounded by water on three sides, and pockmarked with lakes and two major rivers as well as dozens of smaller ones. So it may come as a surprise to hear the Kenai Peninsula has limited freshwater for consumption.

Research from the Kachemak Bay National Estuarine Research Reserve took a closer look at the groundwater sources on the southern Kenai Peninsula, and particularly how the groundwater is connected to streams and peatlands. About half of the lower peninsula is covered in peatland fens, which can help support a food chain that’s more supportive for fish in the streams.

Mark Rains, a researcher with the University of South Florida who worked with the research reserve on the project, told the Kenai Peninsula Borough Assembly that the groundwater on the lower peninsula is formed mostly by ancient, buried streams.

"Your aquifers are old, buried rivers. These re long and they meander, but they’re narrow and they’re thin, and they were buried at different times, so they’re buried at different levels. That’s why you may have a neighbor who drilled down and hit a well at 80 feet, and you have another neighbor who missed that and drilled down and hit one only at 120 feet. They were hitting different channels."

People depend on aquifers for drinking water and for household uses, but groundwater is important for other reasons, too. It provides a source of water for streams that is a constant temperature—colder than the surface water in the summer, and warmer than the winter. This is a good refuge for salmon the streams year-round. It also keeps our streams flowing; Rains said about half the summer streamflow comes from groundwater seeping; in the winter, it’s closer to 100 percent.

The groundwater also support peatlands, which serve an ecological purpose. They hold water and feed it slowly into streams, providing a steady supply of nutrients for the microorganisms that fish feed on.

But it’s not infinite. The aquifers are limited and don’t reach everywhere, and all that water serves multiple purposes besides human use. Rains said one of the reasons the research reserve took this project on was to help local officials make conscious decisions about land management that could affect water use.

"If you take one thing from my talk today, it’s this: You have a finite resource," he said.

Assembly member Willy Dunne noted that the peninsula’s supply of peatlands could be an economic resource, if companies seeking to balance their carbon footprint could purchase carbon credits in the peatlands.

Reach Elizabeth Earl at elizabethearl@gmail.com.