survey of chum salmon redds December 21 downstream of Bonneville Dam found no
spawning fish, triggering the transition from flows that protect spawning chum
to flows designed to protect the redds during egg incubation.
transition comes almost one week earlier than the transition planned by the
interagency Technical Management Team at its Dec. 12 meeting, which was Dec.
Department of Fish and Wildlife biologists completed a survey of redds in the
Ives Island/Pierce Island complex near the Washington side of the Columbia
River, finding that no chum were present, according to Charles Morrill of WDFW
and Tony Norris of the Bonneville Power Administration. Both were present
during the survey, they said at TMT’s Jan. 2, 2019 meeting.
maps of chum spawning areas at http://pweb.crohms.org/tmt/agendas/2018/0117_Ives_Island_Spawning_Areas_2017.pdf.)
chum, listed as threatened under the federal Endangered Species Act, arrived
early this year and chum operations to protect the fish and their redds (nests)
began Nov. 2, about a week earlier than normal. Operations for the chum go on
for about five months into April, but generally transitions in late-December
from spawning to chum incubation flows.
email sent Dec. 21 to TMT members by Doug Baus of the U.S. Army Corps of
Engineers said that the Bonneville Dam tailwater elevation for the incubation
phase of chum operations will be maintained at a minimum 11.3 feet and will be
effective through April 9, 2019, unless otherwise coordinated with TMT (see http://pweb.crohms.org/tmt/agendas/2019/0102_20181221_TMT_Coordination_Chum.pdf).
protecting spawning salmon, chum operations ensure that enough water will flow
over chum redds to protect the redds and fertilized eggs until they emerge in
spring. Initial spawning operations seek flows high enough to protect chum as
they build their redds, but not so high that chum would have been encouraged to
spawn in areas that could be dewatered when flows drop.
operations maintain the dam’s tailwater elevation at a minimum 11.3 feet so
that the fish can move into spawning areas near Hamilton Creek and Ives Island.
However, fluctuations to higher tailwater elevations is limited to 13 feet.
incubation, the tailwater elevation is set simply to keep water over the redds
at Bonneville are currently at about 132,000 cubic feet per second (Jan. 7) and
that is expected to rise to about 142 kcfs this week (see NOAA’s River Forecast
December 14, 2018, “Flows Managed To Aid ESA-Listed Chum Salmon Continuing To
Arrive Below Bonneville Dam,” http://www.cbbulletin.com/441914.aspx
CBB, November 2, 2018, “ESA-Listed Chum Salmon Arrive Early Below Bonneville
Dam; Flow Operations Begin To Protect Spawning,” http://www.cbbulletin.com/441754.aspx
January 19, 2018, “Agencies Identify Spawning Areas For Chum, Confirm Safe
Water Levels Over Redds,” http://www.cbbulletin.com/440103.aspx