NONPOINT SOIREE SICCESS STOIY
Implementing Agricultural Best Management Practices Reduces Nutrients
in 36 miles of the Napa River
I I
Nonpoint source-related nutrient loading from onsite wastewater
treatment systems and agricultural lands contributed to high
nutrient levels in the Napa River. As a result, the Napa River was added to the state's Clean Water Act
(CWA) section 303(d) list of impaired waters in 1976 for nutrients (excess nitrogen and phosphorous).
Landowners, local watershed organizations, and many federal, state and local government agencies
collaborated to implement nonpoint and point source control measures to reduce nutrient loading to
the river. Due to these efforts, nutrient levels have decreased, and the non-tidal portion (36 miles) of
the river has been recommended for removal from the CWA section 303(d) list for nutrient impairment.
Problem
The Napa River watershed is in the California Coast
Ranges north of San Pablo Bay and San Francisco
Bay. It covers an area of approximately 426 square
miles and is a spawning ground for the endangered
Chinook Salmon and Steelhead Trout. The river's
main stem is 65 miles long (Figure 1).
The main nonpoint sources of nutrients are onsite
wastewater treatment systems, grazing lands,
confined animal facilities, agriculture/vineyards,
wildlife, direct wet and dry atmospheric deposition,
and ground water discharges. Point sources of
nutrients include municipal wastewater treatment
facilities, failing sanitary sewer collection systems
and municipal runoff.
In 1976 the river was identified on California's CWA
section 303(d) list as impaired by nutrients resulting
in eutrophication. Eutrophic waters can alter dis-
solved oxygen levels and pH, which can cause failure
to attain beneficial uses including cold freshwater
habitat, warm freshwater habitat, agricultural sup-
ply, municipal and domestic supply, water contact
recreation and noncontact water recreation. The river
is also listed as impaired for pathogens and sedi-
ment, and the Regional Water Quality Control Board
2 (RWQCB-2) has produced total maximum daily
loads (TMDLs) to address those impairments (2008
for pathogens and 2011 for sediment).
Nutrient Impairment Removed
Remains Impaired for Nutrients
Figure 1. The Napa River and Sonoma Creek
watersheds are on the California coast.
Project Highlights
Major activities that helped reduce nutrient loads to
the river since the 1976 listing include:
• Reducing grazed rangeland acreage and the
number of confined animal facilities, as well as
improving conservation management.
Adding language in National Pollutant Discharge
Elimination System (NPDES) wastewater treatment
plant permits in the 1980s prohibiting dry-season
(May-Oct) wastewater discharges to the river.
Developing ranch/farm plans for nutrient and
sediment controls and stream bank stabilization.
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• Funding sediment reduction projects (e.g., stream
bank stabilization) using 319 funds since 1992.
• Implementing the Fish Friendly Farming (FFF) pro-
gram to provide technical assistance to vineyard
landowners and managers with site assessments
and the development of farm plans to control
nutrients and sediments.
• Issuing the 2003 general Waste Discharge
Requirements (WDRs) for confined animal facili-
ties (currently being updated), and Issuing the
2003 conditional waivers of WDRs for confined
animal facilities re-issued in 2015).
• Implementing the 2011 waiver of WDRs for graz-
ing operations to reduce loads from rangelands.
Moving forward, RWQCB-2 is developing a program
to regulate discharges of sediment and nutrients
from vineyards. Continued success in reducing
nutrients in the river will rely on active third-party
watershed programs such as FFF, as well as the
implementation of farm conservation plans, nutrient
management plans, waste management system
plans, and ranch water quality control plans.
Results
Current water quality conditions in the river deter-
mined from data collected between 2002 and 2012
show that nutrient-related numeric and narrative
water quality objectives are being met and impacted
beneficial uses are supported. Although data
collected showed limited exceedances for three
of eight lines of evidence for nutrient impairment,
these exceedances were within what is allowed
in the Water Quality Control Policy for Developing
California's Clean Water Act Section 303(d) List speci-
fications based on the analyte sample sizes (Table 1).
On the basis of these data, it is anticipated that the
State Board will recommend removal of the non-tidal
portion (36 miles) of the river from the state's list of
impaired waters for nutrients in the next listing cycle.
The original 65-mile-long segment is being split into
two segments: a 36-mile-long non-tidal segment
and a 29-mile-long tidally influenced segment.
Partners and Funding
Guidance provided by the U.S. Department of
Agriculture National Resources Conservation
Service (NRCS), University of California (UC)
Cooperative Extension, and local resource conser-
vation districts (RCDs) was key to the adoption of
improved agricultural best management practices
(BMPs). This work, combined with increased water
quality regulation, changes in land use and imple-
mentation of better agricultural practices, have
contributed to reductions in nutrient inputs and
improvements in water quality.
The major partners include U.S. Environmental
Protection Agency, California State Water
Resources Control Board, RWQCB-2, NRCS,
Napa County RCD, Napa County Agricultural
Commissioner, Napa Valley Vintners Association,
Napa County Grapegrowers Association, Napa
County Farm Bureau, Napa County, Rutherford
Dust Society, California Land Stewardship Institute
(managers of the FFF program), UC Cooperative
Extension, Napa Vintners, California Coastal
Conservancy, Watershed Information Center and
Conservancy of Napa, San Francisco Estuary
Partnership, vineyard owners and contractors.
To date, California has invested at least $3,759,659
of CWA section 319(h) funds through nine projects
that supported watershed coordination and agricul-
tural BMP implementation. RWQCB-2 staff mem-
bers responsible for program implementation were
supported with CWA section 319 grant funding.
Table 1. Napa River, Summary of Line of Evidence and Exceedances of Evaluation Guidelines
Line of Evidence
1
2
3
4
5
6
7
8
Analyte
Benthic biomass chlorophyll a
Percent macro-algae cover
Water column chlorophyll a
Nitrite
Nitrate+ Nitrite
Ammonia, un-ionized
Ammonia, total
PH
Numeric Evaluation
Guideline1
< 150 mg/m2
30%
15;ug/L
1 mg/L
10mg/L
0.025 mg/L
0.1-2. 8 mg/L
6.5-8.5 units
Number of Exceedances Per
Total Samples
2 of 16
2 of 17
1 of 40
Oof 120
Oof 120
Oof 6
Oof 120
Oof 24
Evaluation Metric2
Evaluation Guideline (a)
Evaluation Guideline (a)
Evaluation Guideline (a)
Water Quality Objective (b)
Water Quality Objective (b)
Water Quality Objective (b)
U.S. EPA Criterion (b)
Water Quality Objective (b)
Notes:
1 mg/m2 = milligrams per square meter; /jg/L = micrograms per liter; mg/L = milligrams per liter
2 (a) = Listing Factor 4.11, weight of evidence (b) = Listing Factor 4.1, toxicant
(Listing Factor Source: http://www.waterboards.ca.gov/water _ issues/programs/tmdl/docs/ffed
303d _ Iistingpolicy093004.pdf)
I
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-15-001JJJ
December 2015
For additional information contact:
Kevin Lunde, Environmental Scientist
San Francisco Bay Regional Water Quality Control Board
Kevin.Lunde@waterboards.ca.gov
510-622-2431
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