Key
Limiting Factors
A recent review of
existing watershed
studies concluded the seven limiting factors in the Bear Creek
watershed are as follows, basically listed in priority order, with some
of the factors causing the problem:
#1
WATER QUANTITY: 
Low stream
flows, particularly
during summer months, limit summer fish rearing habitat, raise water
temperature and increase competition and the risk of predation.
- Extensive development in the valley has dramatically
altered
stream flow. Three irrigation districts administer water
withdrawals for irrigation and municipal use and often use
Bear
Creek and many tributary streams as conduits between returns
and
diversions.
#2 WATER
TEMPERATURE:
High water temperatures
foster disease
and diminish food for fish. The high stream temperature also
restricts distribution of salmonids to the upper reaches of the stream
system where temperatures are more tolerable. In some
reaches,
water temperature may reach 80 degrees which is lethal to salmon,
steelhead and trout.
- Low summer flow due to irrigation withdrawal, a lack of
shade
along tributaries, and return flow from irrigation significantly
increases summer water temperature.
#3 WATER
QUALITY:
Department of
Environmental Quality
(DEQ) has found Bear Creek exceeds state standards for fecal coliform,
total phosphorous and temperature in the summer, and phosphorous, fecal
coliform and turbidity in the winter. These conditions limit
the
availability of the stream system for both aquatic and human use.
- Discharges and accidental spills from local industries,
storm
sewers and the Ashland sewage treatment plant have impacted water
quality in Bear Creek and occasionally caused fish kills.
#4
SEDIMENTATION:
Sediment and erosion
affect spawning areas, fishery health and water habitat quality for all
aquatic life.
- Residential development, road construction, increased
streambank
erosion and other watershed activities have increased sediment load
after storms.
#5 RIPARIAN
HABITAT:
Riparian habitat is
inadequate,
particularly along tributaries which increases water temperature,
increases erosion and sedimentation, and limits wildlife habitat.
- The dramatic increase in residential and commercial
development
has reduced streamside vegetation; in some areas portions of
tributaries have been piped or mixed with stormwater.
#6 AQUATIC
HABITAT:
The lack of instream
structures
throughout the system limits shelter and hiding areas for fish, reduces
pool habitat, reduces the collection of spawning gravel and increases
water velocity.
- Stream Channelization to accommodate development, the
removal of
instream structures to reduce the risk of streambank erosion, and added
impervious surfaces that increase erosion and concentrate urban runoff
have reduced instream habitat.
#7 FISH
BARRIERS:
Some man-made and natural
barriers still limit or completely restrict fish passage both upstream
and downstream.
Irrigation diversions
and road crossings may restrict fish
movement but an active program has identified and removed barriers and
resolved this as the watershed's principal limiting factor.
Shift
from Fish Barriers to Water Quantity
In 2003-2005, Bear Creek
Watershed
Council (BCWC) used the Rogue Basin Fish Access Team's prioritized
fish barrier list and knowledge of council members to develop an action
plan focusing on cold water anadromous streams. Site visits
were
made to proposed projects on Jackson, Wagner, Ashland and Neil Creeks.
Council members with barrier expertise worked with the Bureau
of
Reclamation Watershed Engineer to develop workable designs.
Projects were prioritized by the Restoration Committee as
Ashland
Creek>Neil Creek>Jackson Creek. Council is also
working
with Headwaters on a Wagner Creek barrier project funded by a grant to
Headwaters.
Recently the previous
limiting factors
in Bear Creek were revised by Jerry MacLeod, retired Oregon Department
of Fish and Wildlife (ODFW) Fishery Biologist. MacLeod found
the
identified barrier removals on Larson, Ashland, Neil, Jackson and
Wagner met fish access needs and that water flow would become the most
important limiting factor. Low summer water flow is a primary
cause of high water temperature and poor water quality.
Sediment,
riparian habitat and aquatic habitat are also limiting factors.
Water flow, temperature, water quality, sediment and riparian
habitat are consistently cited as key limiting factors in the Bear
Creek Watershed and receive focus in the Bear Creek Watershed Action
Plan being developed by the Restoration Committee.
Implementation of the
2005-2007 work
plan will result in the planning and development of a wider variety of
projects designed to resolve some of the identified watershed limiting
factors. The Restoration Committee conceptual approach
focuses on
tributaries grouped in eight units: Ashland - Ashland and
Neil
creeks; Western Lowlands - Willow and Jackson creeks; Western Urban -
Griffin, Elk, Mingus and Coleman creeks; Siskiyou
Slope - Wagner and Anderson creeks; Upper Bear Creek -
Emigrant and Walker creeks; East Cascades - Gaerky, Butler, Myer,
Jeffery, Kenutchen and Payne creeks; Eastern Urban - Larson
and Lone Pine creeks; Eastern Delta - Upton and Whetstone creeks.
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