Water Resources
Hydrology of Alaska
Alaska's abundance of rivers, lakes, wetlands, snowfields, and glaciers
comprise an estimated 40 percent of the Nation's surface water. There
are more than 12,000 rivers in Alaska, and three of those rivers, the
Yukon, the Kuskokwim, and the Copper, are among the ten largest rivers
in the United States. Alaska has more than 3 million lakes ranging from
pond size to 1,000 square miles. Despite Alaska's wealth of water, its
water resources are not uniformly distributed geographically or seasonally.
Annual precipitation ranges from an average of five inches on the Arctic
Slope to an average of 300 inches in the maritime rain forests of Southeast
Alaska. Glaciers and icefields cover about 5 percent and permafrost
underlies approximately 85 percent of Alaska, which affect the timing
and quantity of runoff. Many rivers are affected by ice-jam flooding
during spring breakup, and many are ice covered much of the year.
Despite Alaska's abundant water resources, there are no streamflow
data for over 99 percent of the rivers and streams in the state. The
U.S. Geological Survey, the largest collector of streamflow information
in Alaska, operated 106 water discharge gaging stations in 2000 and
has collected data at more than 400 sites in Alaska since 1908. There
is an average of about one USGS stream gage per 5,500 square miles in
Alaska as compared to the "Lower 48" average of about one
gage site per 340 square miles. The USFWS is the second largest collector
of discharge data in Alaska and is currently operating 30 gaging stations
on three refuges. Data are available from the USFWS for 76 gaging stations
in seven Alaska refuges since 1987. Harsh terrain, remote access, and
large distances in roadless regions contribute to the challenges involved
in collecting hydrologic data. Such challenges limit the size of the
stream gaging network in Alaska.
Water Resources Branch
The Alaska National Interest Lands Conservation Act of 1980 establishes
purposes for each of Alaska's National Wildlife Refuges. One purpose
of every refuge is "to ensure, to the maximum extent practicable
and in a manner consistent with the other purposes of each refuge, water
quality and necessary water quantity within the refuge." To implement
this mandated refuge purpose, the Water Resources Branch documents the
occurrence, quantity, distribution, movement, and quality of water within
Alaska refuges. Types of data collected include stream flow and water
quality, lake elevation surveys, lake bathymetry, and water well logs.
 Data
collected by the Water Resources Branch are used to quantify water requirements
and obtain legal use of the water through the State of Alaska. Acquiring
State water rights, in addition to already existing Federal reserved
water rights, will provide protection of fish and wildlife habitats
and the natural biodiversity of aquatic resources, as well as to allow
an adequate water supply for refuge campgrounds, administrative offices,
and facilities. The Water Resources Branch provides technical assistance
for all water related issues to the refuges, field offices, and regional
office upon request. The Branch also researches title navigability issues
for planning and management purposes.
Last updated: September 4, 2008
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