[env-trinity] from today's Davis Enterprise

Mon Jan 20 11:11:43 PST 2014

Amazing that so many diversions remain unscreened in the Sacramento River
system (98% reported below). The Scott River's diversions are 100% screened
due to potential coho reaches receiving high priority. With so many listed
species (not just sturgeon) in the Sacramento system, why has it taken so
long there to make a significant dent in fish screening needs?

Curious,

Sari Sommarstrom

From: env-trinity-bounces at velocipede.dcn.davis.ca.us
[mailto:env-trinity-bounces at velocipede.dcn.davis.ca.us] On Behalf Of Moira
Burke
Sent: Sunday, January 19, 2014 2:16 PM
To: Tom Stokely; env-trinity at velocipede.dcn.davis.ca.us
Subject: [env-trinity] from today's Davis Enterprise

River water diversions threaten sturgeon, study shows

<http://www.davisenterprise.com/media-post/sturgeon-photo/attachment/green-s
turgeonw/> Green SturgeonW

Sturgeon are one of the largest and oldest families of bony fish in the
world, with 15 of the remaining 25 species listed as critically endangered
due to over-fishing, habitat changes and habitat loss. UC Davis/Courtesy
photo

By  <http://www.davisenterprise.com/author/pat-bailey/> Pat Bailey
 <http://www.davisenterprise.com/print?edition=2014-01-19&ptitle=A9> From
page A9 | January 19, 2014 |
<http://www.davisenterprise.com/local-news/ucd/river-water-diversions-threat
en-sturgeon-study-shows/#commentBox> Leave Comment

UC Davis researchers have used laboratory studies to estimate the risk to
young green sturgeon, which may be killed by unscreened pipes that divert
water from the Sacramento River into adjacent farm fields.

The study confirms that this ancient protected fish species may be
jeopardized by the current system of water diversion pipes. The findings
also suggest that the threat could be lessened by diverting river water more
slowly and over longer periods of time, meeting agricultural needs while
conserving the green sturgeon populations.

The researchers report the study results this week in the online journal
PLOS ONE.

"Our work highlights the potential danger that unscreened water diversions
pose to migrating juvenile green sturgeon - a risk that is poorly understood
for this species," said Jamilynn Poletto, a doctoral student in the
laboratory of the study's lead researcher Nann Fangue, an assistant
professor in the department of wildlife, fish and conservation biology.

Sturgeon are one of the largest and oldest families of bony fish in the
world, with 15 of the remaining 25 species listed as critically endangered
due to over-fishing, habitat changes and habitat loss.

One of those endangered species is the green sturgeon, which lives in
coastal waters of the Pacific Ocean, from Alaska to Mexico. A specific
population of these green sturgeon spawn only in the Sacramento River and is
listed as threatened under the U.S. Endangered Species Act.

Unscreened agricultural water-diversion pipes that line the Sacramento River
banks and levees have long been considered a threat to native fishes, but
there has been limited data assessing their impacts.

Water is diverted from the rivers for agricultural use at more than 3,300
locations throughout the Sacramento-San Joaquin Watershed, and 98 percent of
the diversion pipes are unscreened, posing a significant threat to juvenile
green sturgeon.

Fish drawn into the pipes are either killed directly by water pumps or die
when they are stranded in seasonally irrigated canals, ditches and fields
when the water supply is withdrawn.

In an effort to quantify that threat, Poletto, Fangue and their colleagues
simulated river conditions with an experimental flume, complete with an
unscreened diversion pipe, angled bank and flowing water. The study was
conducted in collaboration with the J. Amorocho Hydraulics Laboratory, which
is run by M. Levent Kavvas, a UCD professor of civil and environmental
engineering.

The research team found that a surprisingly large percentage of the young
sturgeon placed in the flume was drawn into the unscreened pipe. Data from
the study estimate that up to 52 percent of green sturgeon that pass within
1.5 meters of a water diversion pipe just three times could become
irreversibly drawn into the pipes.

Unlike young Chinook salmon previously tested in the flume, the young green
sturgeon did not demonstrate behaviors that would cause them to recognize
and avoid the intake pipes.

The green sturgeon also were trapped in the diversion pipes at a higher rate
than the Chinook salmon observed in the flume.

The researchers suggest that this difference between the sturgeon and the
salmon could be explained by the fact that the sturgeon have fewer sensory
organs that detect changes in water velocity than do the salmon.

The study also demonstrated that a 50 percent reduction in the flow of water
through the diversion pipe resulted in a 78 percent decrease in the number
of fish drawn into the pipe.

The researchers note that extrapolation of their findings to in-river
conditions must be done with caution, but they suggest that new water
diversion strategies, such as slowing the rate of water diversion, might be
successful in balancing agricultural needs in the Sacramento Valley with
fish conservation priorities.

"To create effective management strategies for green sturgeon and other
native fishes, we first must understand the factors like these water
diversions that could be impacting population declines," Fangue said.

In addition to Fangue, Poletto and Kavvas, the researchers on this study
were Timothy Mussen, Dennis Cocherell, Jon Reardon, Zachary Hockett, Ali
Ercan, Houssein Bandeh and Joseph Cech, Jr.

The study was funded by the California Department of Fish and Wildlife's
Ecosystem Restoration Program, the UC Agricultural Experiment Station, the
U.S. Department of Interior's Anadromous Fish Screen Program and the
National Science Foundation.

- UC Davis News

<http://www.davisenterprise.com/media-post/sturgeon-photo/attachment/green-s
turgeonw/> 

M o i r a  B u r k e

tel 707 678 3591  

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