[Birdtalk] No water for birds at Bear River Refuge?

Wed Sep 5 21:54:16 MDT 2007

 Betsy:

Thank you for posting this explanation by Bridget.? I sent Bridgett an e-mail asking what is the view of Refuge management for further impacts of reduced flows from the Bear River in future years, if Utah develops the Washakie Reservoir.? The legislature passed the Bear River Development Act in recent legislation and is on the path to build this reservoir.? The Bear River Development Act was designed to begin engineering studies, rights of way, water rights, etc., as a prelude to it.? 

Regards,

Bill Fenimore
Utah Audubon Policy Advocate
1860 North 1000 West
Layton,  UT  84041-1858
801-525-8400 Store
801-525-8415 Fax
801-699-9330 Cellular

-----Original Message-----
From: Betsy_Beneke at fws.gov
To: birdtalk at utahbirds.org
Sent: Wed, 5 Sep 2007 2:14 pm
Subject: [Birdtalk] No water for birds at Bear River Refuge?

Dear Utah Birders:

Refuge staff often gets questions from the visiting public about why we
aren't trying to put, or keep, more water on Unit 2, which is the one
encircled by our auto tour route.  They'd like to see more birds, and more
habitat for the birds, when they visit.  It's a complicated issue - with no
quick and easy answer.  I asked our wildlife biologist, Bridget Olson, to
write something up that I could give to our refuge volunteers and tour
guides, so that they had better information with which to answer visitor
questions.  I think Bridget did a very good job of trying to explain our
considerations, and decided I would share it with all of you as well.

If you have any questions, you're welcome to contact me for further
clarification.

Betsy Beneke
Outdoor Recreation Planner
Bear River Migratory Bird Refuge

Prioritization of Wetland Units at Bear River Migratory Bird Refuge

In most years, the Refuge does not have enough water supply from the Bear
River  to maintain all the wetlands at their "optimal" water levels
throughout the driest part of the year (July-August).  That "optimal"
management level is determined based on the habitat needs or criteria of
our priority waterbird species, past distribution and abundance of priority
species on the Refuge, as well as growing conditions for desirable wetland
plants and associated invertebrates.

Because we rarely have enough water to keep all the units at desired
management level, we have to prioritize which units will be kept at full
pool, and which will be allowed to go dry. Before we select the units to
keep full, we have to first estimate the amount of flow that will be in the
River in July and August.  There are a few key pieces of information we
have to collect and consider to determine this:

1)The Bear River is fed by run-off from snow pack in the Bear River
watershed.  The National Weather Service, as part of NOAA (National Oceanic
& Atmospheric Administration), puts out a "Water Supply Outlook for the
Eastern Great Basin" that forecasts how much volume of water there is going
to be in each of the major watersheds in Utah.  They publish the Outlooks
January-June each year.  The one that is most important to us is the April
forecast.

2) Bob Green, Former Chief of Water Resources Division, USFWS Region 6,
created several models for us that took into account the amount of water in
the River that would be lost to evaporation before it got to Corinne, the
amount of water lost to evaporation and evapo-transpiration on the Refuge,
and the amount lost in the process of "delivering" water to a particular
Refuge unit.  We can multiply the predicted River volume from NOAA with the
median monthly flow at the Corrine gauge (that Bob compiled) to get the
best estimate of Bear River flow coming into the Refuge in July and August.
Bob also calculated that  1cfs (cubic foot per second) of flow in the Bear
River (in July and August) will sustain 58 acres of wetland habitat on the
Refuge.

Using the April volume forecast for the Bear River from NOAA, and Bob's
formula, we can then estimate the number of acres we can keep "wet" or at
full pool for July and August.  We then use this data to prioritize the
wetland units in April of each year during our annual habitat management
planning meeting.

We DO take into account the fact that the public may lose some viewing
opportunity, and the hunting community may have fewer areas to hunt.

To change our minds mid-stream (pun intended), or in the middle of the
summer when loss to evaporation is at it's highest, is a VERY inefficient
way to use the little water we do have.  That's because it takes a lot more
water to re-fill a dry delivery canal and a dry unit than it does a wet
canal and wet unit.  The most efficient way to use our water is to decide
ahead of time which areas will get water and which ones we'll have to let
go dry.  Since we planned this ahead of time, there's no need to suddenly
add more water to a particular unit.

Botulism & Water Levels

Periodically, we may have a rain event in the summer months that will
increase the amount of flow in the Bear River.  We would be tempted to use
that increased flow to bring some units back to management level or add
some water to dry units.  However, we have to let that water pass through
our canals, and out onto the Willard Spur instead.  If we used the water to
re-fill a unit that was in the process of drying it would re-flood the wet
mud zone.  By temporarily re-flooding this area (temporary because we don't
have a sustained increase in water supply) it creates anaerobic soil
conditions that favor the growth and expansion of the botulism bacteria
that is responsible for avian botulism outbreaks.  By passing the water
instead, we are attempting to avoid environmental conditions that favor the
growth of the botulism bacteria, thus decreasing our chances of avian
botulism outbreaks.

The end...

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