in other words
august1
2019
7
A Word from the Watershed: The Nehalem River and Lethal Heat
By Corrie Aiuto
For years, summer tem-
peratures in the Nehalem
River have been too high,
negatively impacting salmon
strength and vitality. The Up-
per Nehalem Watershed Council (UNWC) needs
your help to address the human-made causes.
Recently, on a hot weekend afternoon,
my family and I sought out the cool relief of Rock
Creek. As I waded out towards the middle of the
stream, with my pants rolled up around my calves
and my feet delighted, I began thinking about the
complexity of life in the water. Sunlight and oxy-
gen, plants and fish, living organisms and decay-
ing matter, all must strike a Goldilocks balance to
sustain the aquatic systems we know. Deficiencies
in one ingredient or excess of another can bring the
whole system out of balance and begin a series of
reactions, impacting creatures all along the food
chain.
One excessive ingredient in our waters is sun-
light, or more scientifically, solar radiation. We might
not think of sunlight as a source of pollution, but when
enough solar radiation heats a water body beyond what
the creatures inside can endure, that’s exactly what it
is: sunlight pollution. To maintain water quality, envi-
ronmental agencies look at what we traditional think
of as pollutants, such as oil spills, chemicals, and
wastewater, and also things like excess bacteria
and sunlight.
In 1972, the Clean Water Act expanded
water quality standards for U.S. waterways set
in place by the earlier Federal Water Pollution
Control Act of 1948. As part of this expansion,
each state is required to establish a list of polluted
water bodies and add them to what is known as
the 303(d) list. Total Maximum Daily Limits, or
TMDLs, were created, which set the total amount
of a pollutant, including solar radiation, that can
exist in the water without lowering water quality.
In the case of stream temperatures, TMDLs focus
on preserving water quality for salmon spawning,
rearing, and migration. As early as 1998, the Ore-
gon Department of Environmental Quality (DEQ)
included the main stem of the Nehalem on the
303(d) list as temperature impaired, and by 2003
the TMDL report added many of the tributaries for
the same problem. The Nehalem River, even 21
years ago, was too hot for some species of salmon.
Stream temperature data is taken and recorded
in a number of ways and one common method uses a de-
vice called a thermograph. The small, battery-powered,
cylindrical device is about six inches long and is left
in the water for months at a time, taking temperature
readings and storing them internally to be downloaded
and analyzed later. TMDLs use seven day averages of
such temperature data. The UNWC uses thermographs
following DEQ protocol to ensure accuracy and places
them in streams in the spring or early summer to record
peak temperatures. The height of summer heat usually
occurs at the end of July through August with tempera-
tures dropping by late September.
In the summer of 2000, the DEQ took tem-
perature data from over 40 in-stream sites in the Up-
per Nehalem and over 20 sites in the Lower Nehalem.
They also conducted an infrared flyover, taking surface
temperature data from an aerial view. Unsurprisingly,
the data showed that much of the Nehalem was warmer
than the maximum temperature threshold for salmon
migration and rearing, reaching lethal limits in the
main stem.
Some stream temperature increases, or heat
loading, are part of natural seasonal fluctuations, but
most are the result of human activity. Logging, agri-
culture, roadways, and wastewater treatment are a few
of the ways we contribute to heat loading. Removing
trees from riparian areas reduces shade cover, and run-
off from developed land, roads, and water treatment
facilities adds warm water to the stream.
The well documented increase in temperatures
impacts the watershed in many ways. Most notably,
salmon struggle to survive in warm water. For most
species, anything over 55° F is too warm for spawning
and over 65° F is too warm for rearing. This puts strain
not only on salmon populations, but also on creatures
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since 1981
that feed on live and decomposing salmon. The
list of creatures depending on the redistribution
of nutrients from the salmon life cycle is long,
spans the length of the Pacific Northwest food
chain, and includes us.
Another result of warmer waters is a reduction
in dissolved oxygen. As the temperature rises,
water chemistry changes, making less oxygen
available. This has consequences for both ani-
mals and plants and gives advantage to some
warm-loving invasive species.
Wading in Rock Creek provided a cool break
from the summer heat for this warm-blooded
homo sapiens. But the cold-blooded creatures
who swim and squirm and crawl through the
waters of the Upper Nehalem Watershed are
feeling the heat. Those of us who live beside
them must work harder to ensure their habitat
not only exists, but also provides a necessary
cool refuge in our warming planet.
You may be wondering how you can help. One
key step is understanding the importance of diversely
forested riparian areas along the entire length of the riv-
er, and particularly at the headwaters of a river or tribu-
tary. The Oregon Forest Practice Act does not require
riparian buffers to be retained along non-fish bearing
streams with an average annual flow of less than 2
cubic feet per second. This means that areas around
headwaters can be clear cut if there are no fish and the
flows are low enough. In order for streams to con-
tribute cold water to the main stem, they must be
allowed shade cover from the source all the way to
the bay. Small landowners can help by not clearing
trees and vegetation that are close to shore. Plant-
ing trees and contacting your state representatives
about expanding riparian buffers are a couple other
steps you can take.
Another helpful step is embracing the concept
of natural valley storage. This refers to the land’s
capacity to store water in the winter and release it
in the summer. Increased storage can help mod-
erate stream temperatures and keep water cooler,
longer. Beaver are particularly good at increasing
natural valley storage by creating dams, pools, and
wetland areas. Support beaver. If you are a land-
owner who encounters beaver, consider tolerating
them for the benefits they bring the land, or reloca-
tion rather than extermination.
Finally, support your local watershed council.
Donate. The UNWC operates almost entirely on
grant funding, which is time consuming and competi-
tive. If you have the resources to financially support
your watershed council, do so. Volunteer your time.
The UNWC needs board members first and foremost,
but they also need folks to tend the native plant nursery,
and help in the office with administrative tasks. Stay
tuned and join us for volunteer tree planting events this
coming fall and winter. Together we can help restore
cooler waters to the Nehalem River.
The next Upper Nehalem Watershed Council Board
Meeting is scheduled for Thursday, August 22, 5:30-
7:30 pm at the UNWC office, 1201 Texas Avenue.
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