Last week I attended an excellent
forum on “riparian health’ presented by Wayne Elmore and John Anderson of the
National Riparian Service Team. (Riparian areas are those alongside rivers and streams.) I
took away some ideas about “building a better sponge.”
It was refreshing to hear John Anderson say, “There is lots of
water out there, it is just leaving in a hurry…the water all runs away without being
saved for late summer.”
Old timers in Scott Valley have indicated that, over the years:
(1) The water table has dropped;
(2) Some perennial streams are now intermittent;
(3) There is a lot of sediment in the streams; and
(4) Riparian and upland vegetation has changed.
Wayne Elmore started out by defining ‘riparian health.” He looks for stability – for soil, water and
vegetation to interact in such a way that the “profile” of the stream is
maintained in a 30 year flood event. He also looks for retarded flow velocity – where
the energy is taken out of the flow and directed toward keeping water on the land longer
to recharge aquifers and raise water tables.
He described how certain riparian plants called “stabilizers”
build a cradle along the sides and under the river. These plants, (sedges, rushes and
reeds,) have strong, fibrous root systems that go deep into the ground. For instance,
sedge samples taken in a cube 12X12X16 inches have contained from 18-23 miles of roots;
and rushes from 7-8 miles of root. Willows combined with sedges have the stabilizing
capacity to hold a bank equivalent to anchored rock.
The nest of tangled roots holds banks against erosion. Many of these
plants “propagate” or spread out by their roots. The resilient plants can also
withstand flooding and trap sediment along river sides, building up new banks and poking
through the mud and silt with new growth. Scott River has a lot of non-native Nevada
bluegrass and red top. This has a weak root system, (only 2-3 miles in the sample cube,)
and cannot hold up to flooding and erosion.
Anderson described how “woody debris” or log jams can also
slow flow velocity, trap sediment, build up streams and provide “roughness” that
creates pools and fish habitat complexity. He talked about when a river runs in an
incised, channelized “V.” There can
be a loss of “hydrostatic pressure.” Instead of holding the water profile, the
lack of pressure pulls water from adjacent ground into the stream.
Deposited silt or soil is bedding ground for the “colonizing”
plants. These spread by roots or runners and often establish during drought. Colonizers
include: watercress, coyote and sandbar willow, cottonwood, alder, red cedar and spike
rush. These will promote sinuosity or bends in the river and decreases gradient. This
slows the river down. When the river slows, it drops sediment instead of eroding banks and
scouring river beds.
Over time, the river gets narrower and the bed builds up. This
increases water storage dramatically in the plants and soil. In Elmore’s Bear Creek
experiments, water storage in the study area in 1978 was 500,000 gallons/mile. After
management changes in 1994, storage was 1,500,000 gallons/mile. The savings more than made
up for consumption by increased vegetation and produced increased stream flows.
Upland juniper was also targeted as an important Scott Valley issue.
Water sheets off juniper hills quickly, without infiltrating into the ground. The soil
stays frozen longer. Organic matter does not go back into the soil. Junipers are known to
suck up lots of water and store it. It was found that when perennial bunchgrass came out
in the spring, there was little water in the soil to support it.
Elmore cited that a tree on an 80 degree day when the soil was fully
saturated, would use about 35 gallons a day. In Scott Valley with our eastside juniper
invasion, there are places that are consuming more than 400 gallons a day an acre.
He indicated that cutting the juniper and leaving the debris in
place, then burning of debris and brush, repeated at ten year intervals, was the best
treatment they had found for restoring native grasslands. He also suggested thinning some
of thick fir stands.
On another note, local artists and crafters are wanted for the Scott
Valley Bluegrass Festival. Call Cathy at 467-5752. The new Scott Valley FOCUS Family Resource
Center will open soon in Fort Jones (up-street from Scott Valley Bank.) They really need
donations of furniture before their grand opening in mid-May. They also would welcome more
volunteers. Call Kathy Murray at Scott Valley Feed 468-2434. See you at the Pleasure Park
Rodeo on May 2 http://www.scottvalley.org/SVrodeos.htm
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