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Section 319
NDNPDINT SOURCE PROGRAM SUCCESS STDRY
Changes in Irrigation Practices Reduce Turbidity in the Lower Yakima River
WatPrbndv Imnrnvpd Erosion from irrigated agricultural lands has caused the waters
of the lower Yakima River to become impaired by suspended
sediment, turbidity, and the pesticide DDT, causing it to be placed on the state's 303(d) list
of impaired waters. As a result of better irrigation practices through the conversion from
furrow to sprinkler or drip systems, area farmers have achieved interim total maximum daily
load (TMDL) criteria for turbidity at three of the four primary irrigation water return drains,
and made significant progress towards meeting TMDL targets at all other sites.
Problem
The Yakima River flows for over 200 miles
through south-central Washington, and is one
of the most intensively irrigated and agricultur-
ally diverse areas in the United States. The
confluence of the Yakima and Naches Rivers
(a tributary) at the city of Yakima divides the
Yakima River into the "upper" and "lower"
portions. During a normal irrigation season at
least 300 tons of sediment contaminated with
pesticides and other pollutants entered the
lower Yakima River from irrigated farmland,
interfering with fish and their habitat. Studies
have shown that fish in the lower Yakima River
have one of the highest concentrations of DDT
in the country.
In 1996 the lower Yakima River was placed on
Washington's 303(d) list for impairments from
suspended sediment, turbidity, and DDT; and
in 1998 the Washington State Department
of Ecology (Ecology) established a TMDL.
Implementation of the TMDL is scheduled over
a 20-year time span, with interim targets set at
5-year intervals. The fifth year targets, set for
2002, included meeting the state water quality
criterion for turbidity in the mainstem Yakima
River, and achieving a maximum 90th percen-
tile turbidity of 25 NTU (nephelometric turbidity
units) at the mouths of the four major tributar-
ies in the lower Yakima. Prior to the develop-
ment of the TMDL, turbidity levels commonly
reached 300 NTU or higher.
90th Percentile Turbidity at Drainage Outlet Sites
Irrigation Season
350"
300-
250-
s
f 200-
| 150-
100-
50-
. 298
• 1997 B1998 1 1999 2000
• 2001 2002 B2003
TMDL Goal: 25 NTU
12536
!81
42 I48 1111 ffl49«
nn n ' 'H18 aie rnn25 a 2in 15 6
II II II II II In • Illllllnlll nnn..n_
Granger Drain Sulphur Creek Spring Creek Snipes Creek
Graph represents decreases in turbidity at the four major tributaries
in the lower Yakima, with a goal of 25 NTU 90 percent of the time.
Project Highlights
To implement the TMDL a landmark partner-
ship was formed between two irrigation
districts in the Yakima Valley—the Sunnyside
Valley Irrigation District and the Roza Irrigation
District. Under the Roza-Sunnyside Board of
Joint Control (Board), the two districts adopted
a comprehensive Water Quality Policy, with
support and input from local farmers and other
landowners, that set specific on-farm turbidity
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targets. If on-farm targets are not met, the
landowner is responsible for taking corrective
action by submitting both a short-term and
a long-term Water Quality Plan for how the
targets will be achieved. If the landowner
continues to be in violation of the water quality
policies, the Board can reduce water delivery
services to the farm until the plan has been
implemented and subsequent monitoring
indicates compliance. Over 200 plans have
been filed with the irrigation districts.
The Board worked closely with many farmers
who voluntarily converted well over 20,000
acres from water-intensive and erosive rill and
furrow irrigation methods to sprinkler or drip
systems to reduce erosion. Each year one
lateral irrigation ditch is converted from open
ditch to pipe, which reduces evaporation and,
in many cases, delivers pressurized water to
farms, making it easier for growers to utilize
drip and sprinkler systems. Other best man-
agement practices implemented to control ero-
sion include the construction of settling ponds,
filter strips, and the use of polyacrylamide—a
substance that binds to soil while allowing
water infiltration.
Results
Effectiveness monitoring conducted by
Ecology in 2003 shows that three of the four
major agricultural drains met the TMDL cri-
teria for turbidity. While the fourth drain did
not meet the criteria, it did show a sediment
load reduction of approximately 80 percent.
Progress was also observed in the mainstem
Yakima River, with reductions of total sus-
pended sediment loadings between 50 and
70 percent in 2003 (as compared to 1995).
Partners and Funding
The success of this project is due to support
from Ecology, South Yakima Conservation
District, North Yakima Conservation District,
Yakama Nation, Benton Conservation District,
Roza Irrigation District, and Sunnyside Valley
Irrigation District. Since 1994, funding has
totaled more than $2.5 million. More than
$1 million in section 319 funding supported
Ecology's work in developing and implement-
ing the TMDL; and approximately $200,000
in section 319 funding supported rill irrigation
conversion, water quality monitoring, and other
technical assistance. The U.S. Department
of Agriculture (USDA) Natural Resources
Conservation Service provided $2.3 million
through the Watershed Protection and Flood
Prevention Act (PL-566), along with additional
support from USDA's Environmental Quality
Incentives Program. Approximately $10 mil-
lion in low-interest state revolving loan funds
from Ecology supported upgrades to irriga-
tion systems. Grants from the U.S. Geological
Survey, Yakama Nation, and Washington State
University Cooperative Extension Research
Station at Prosser funded construction of set-
tling ponds and filter strips. Additional support
came from the Washington State Conservation
Commission; conservation districts; and
the U.S. Department of Interior's Bureau of
Reclamation. This funding helped leverage over
$6 million from landowners themselves.
I
5
Q
'. U.S. Environmental Protection Agency
\ Office of Water
a Washington, DC
EPA841-F-05-004V
September 2005
For additional information contact:
Ryan Anderson
Washington State Department of Ecology
509-575-2642
rand461@ecy.wa.gov
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