Dry summers could mean trouble for use of lake water for North Slope ice roads, study says
Guidelines for taking water from North Slope tundra lakes should be refined to consider rare summer droughts and other factors, study says
Lakes and connecting streams in the northeastern part of the National Petroleum Reserve in Alaska are seen from the air on June 26, 2014. A newly published study examines oil industry use of water from tundra lakes in varying weather conditions. (Photo by Bob Wick/U.S. Bureau of Land Management)
For decades, the oil industry has built ice roads for seasonal travel across Alaska’s North Slope. The ice roads, built and used in the hard-freeze winter seasons, are designed to be thick enough to protect the tundra from vehicle weights but temporary enough to melt away in summer, avoiding the myriad negative impacts created by permanent roads.
It takes about 1 million gallons to build a mile of ice road, according to ConocoPhillips. North Slope water use totaled 121 million gallons, only about 0.02% of the amount authorized for the season, according to the most recent data from the Alaska Division of Mining, Land and Water.
But how much water for roads is too much for lakes to sacrifice?
The answer depends on summer weather conditions, according to newly published research. In dry years, the standards used by the regulatory agencies may be too lax, said the study, published in the journal Water Resources Research.
A general rule used by the Alaska Department of Natural Resources and partner agencies is that companies may take 20% of the water volume in lakes without fish, including ice on the top and liquid water below, said Henry Brooks, a resource manager in the department’s water management unit. Snowmelt dependably refills those lakes, he said. “Mother Nature pretty much takes care of things up to the 20% level,” he said.
In lakes with fish that are considered resistant to low-water conditions, like stickleback and blackfish, up to 30% of below-ice water may be withdrawn. For lakes with fish that are considered sensitive, like whitefish and grayling, the below-ice water limit is 15%, Brooks said.
The state guidelines are usually adequate, said Christopher Arp of the University of Alaska Fairbanks, a co-author of the new study.
However, water withdrawals in dry years could cause serious problems for fish and the water systems, he said. When there are drought conditions, which are rare on the North Slope, withdrawals “can have a significant impact on downstream fish and movement of fish from rivers to lakes in downstream habitat,” he said.
After a single dry summer, according to the study, lakes will need three successive years of snowmelt to be replenished if water is withdrawn in volumes allowed in current regulations. Such water use after a dry summer will lead to intermittently dry streams for the following three years, the study said.
Additionally, using the same lakes for water withdrawals for several consecutive years — even in average conditions — “results in a new hydrologic equilibrium in low flow and runoff that produce several weeks of impassable stream conditions for fish during migration periods,” the study said.
The study used a combination of field measurements and modeling that considered various weather scenarios. The field site was the Crea Creek watershed, where there are two lakes that regularly supplied water and ice chips for roads used to develop ConocoPhillips’ Greater Mooses Tooth 1 project in the National Petroleum Reserve in Alaska (NPR-A).
The study recommends refinements to state management of water withdrawals. Those include standards that consider summer weather patterns, which are becoming more extreme with climate change, and more flexibility to make quick changes if needed.
“The problem is the water withdrawals occur in the winter and the drought conditions would occur in the following summer,” said Arp, who is with UAF’s Institute of Northern Engineering. If there is a dry summer, “it would be a very good idea for managers to not permit as much water withdrawal in the following winter.”
It is also wise for companies and regulators to spread their water withdrawals among several lakes, a practice that is already common, Arp said.
Most of the tundra lakes on the North Slope are used by fish, but there are many unanswered questions about the fish populations, including what type of fish are in the lakes and when they use those water bodies, Arp said. For now, there are fish surveys in the summer to inform water-withdrawal standards, he said. “But they’re not really interested in what fish are there in the winter, and they’re usually not the same,” he said.
An ongoing research project is testing DNA found in lake water sampled in the spring to try to better understand overwintering fish distributions, he said.
Fortunately, for both fish and oil companies on the North Slope, there are abundant lakes to choose from in the areas where most of the operations occur.
Being able to use ice roads in the winter is a really good thing. But to do that, you have to have a bunch of lakes and a bunch of water. And that really is not the case in that area. – Christopher Arp of the University of Alaska Fairbanks, a co-author of the new study
Being able to use ice roads in the winter is a really good thing. But to do that, you have to have a bunch of lakes and a bunch of water. And that really is not the case in that area.
– Christopher Arp of the University of Alaska Fairbanks, a co-author of the new study
“Being able to use ice roads in the winter is a really good thing. But to do that, you have to have a bunch of lakes and a bunch of water,” Arp said. “And that really is not the case in that area.”
Recent UAF research, both in a white paper and a peer-reviewed published study, casts doubt on industry’s ability to travel safely across the ANWR coastal plain for a variety of reasons. In addition to the scarcity of freshwater, the area – wedged in a relatively narrow strip between the Arctic Ocean and the Brooks Range – is much hillier and windier than the Central North Slope or portion of the NPR-A where oil activity is taking place. The combination of topography and wind means there are typically many wind-scoured areas with too little snow in winter to support the weight of industrial vehicles, according to the UAF research.
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