At the start of her graduate school hydrology studies in Kachemak Bay, researcher Tyelyn Brigino found herself concerned that most people don’t understand groundwater resources.
“We don’t think of where that water comes from most of the time,” she said.
“If someone wanted to divert water from a river that would be easy to manage, but that is so much harder for groundwater. Groundwater is important to salmon, but people don’t often think about groundwater when they think about salmon,” she said. “In Alaska we don’t know how much groundwater there is.”
Brigino was the lead author of a research article on groundwater in the Kenai Peninsula Lowlands, published recently in the online professional journal River Research and Applications. On Oct. 23 she successfully defended her doctoral research at the University of South Florida in Tampa.
The research documents temperature modulating of groundwater discharge to salmon-bearing streams, including the impact of those temperatures on salmon spawning habitat.
The article notes that the Kenai Peninsula Lowlands encompass five major watersheds that drain into Cook Inlet, mostly roadless areas with populations concentrated along the coast. These watersheds support coho, pink and Chinook salmon plus steelhead trout and Dolly Varden char. They are a major component of the Southcentral Alaska economy, supporting commercial, sport and subsistence harvests.
Hydrology itself is the study of the distribution, movement and physical, chemical and biological properties of water and beneath the earth’s surface, as well as in the atmosphere. It involves the movement of water through evaporation, condensation, precipitation, infiltration, runoff and plant transpiration.
Groundwater is water that is stored underground in tiny spaces, cracks, and pores within soil, sand, gravel and rock layers called aquifers, geological formations consisting of permeable material capable of storing significant quantities of water. These aquifers may consist of unconsolidated sands and gravels, permeable sedimentary rocks such as sandstones or limestones, or fractured volcanic and crystalline rocks.
Groundwater is recharged by rainwater and snowmelt and water that leaks through the bottom of some lakes and rivers, or when water supply systems leak.
These outreach events to K-12 public school classes and through the reserve’s coastal training events are a rare experience for a graduate student, she said. The fellowship also financially supported her move from Florida to Alaska, to expand her research across seasons, something that she otherwise would not have been able to do.
The work her research group has done has been used for water source protection through land acquisition efforts. While KBNERR does not own or manage any land, the reserve works closely with Kachemak Heritage Land Trust, and they can prioritize conserving parcels that might be the best for protecting salmon habitat. KBNERR and KHLT host joint outreach events, such as Fish Need Land too, where we share the relationship between land and salmon habitat, Brigino said. The research reserve works to share science with decision-makers as part of its Coastal training program led by Syverine Bentz.
A major challenge in protecting fish habitat on the Kenai Peninsula and elsewhere in Alaska is groundwater withdrawals remain largely unregulated in the state.
Her research group published a study earlier this year focused on groundwater contributions to streamflow on the Kenai Peninsula Lowlands.
“We found that groundwater supports 70% of annual streamflow, so not only is groundwater supporting stream temperatures, it’s also heavily supporting streamflow in this region,” Brigino said. “We think about commercial facilities that could extract groundwater, but there’s also plenty of household supply wells. Many of these household supply wells are on hillslopes near by streams. Many landowners pay for well drilling by the foot, so once they get sufficient yield, there is no motivation to drill deeper. Many of these wells tap into and withdraw from the same aquifers that support groundwater discharge to streams. There’s that delicate balance between both human users and in-stream users.”
Brigino said she feels there are a lot of great opportunities to maintain suitable habitat in the watersheds feeding into Kachemak Bay and that there’s a lot of science to support that effort. These opportunities include several protections that already exist, she said.
These include limitations to certain development within a certain radius of mapped anadromous streams, places where salmon have been documented.
Based on surveys and estimates by the Alaska Department of Fish and Game, the Anadromous Waters Atlas documents less than 50% of the actual streams, rivers, and lakes used by anadromous fish in Alaska. There are also reservations of water, legal protections for minimum flows and levels in streams.
“While these protections are good, they can be limited,” Brigino cautioned.
“For example, we showed that aquifer water can travel 100 to 200 miles in winter or summer before reaching an ecological threshold. Expanding development setbacks to this distance is not feasible. However we can work to expand mapping of anadromous streams,” she said.
“There are many efforts within the state to do so. There is also a lot we can do as a community,” she said. “Salmon is a cultural touchstone in Alaska, and our goal is to share this science back with the community so we can be good stewards of our land and water resources.”
Leave a Reply