Elkhorn Slough (ELK) National Estuarine Research Reserve January to December, 1996 Water Quality Metadata Report Latest Update: November 9, 2001

Water quality monitoring is conducted at 26 National Estuarine Research Reserves (NERR)
at four locations within or adjacent to the reserve. The following parameters are collected at
least every 30 minutes: water temperature, specific conductivity, salinity, percent saturation,
dissolved oxygen concentration, water depth, pH and turbidity. All water quality data loggers
will be deployed from a known depth from the bottom at each site. Research objectives Non-point
source pollution is among the highest research priorities within the Elkhorn Slough watershed.
Agriculture and specifically strawberry production, is a significant land use in the watershed,
with agricultural production making up one quarter of land use and strawberries comprising about
8% of the Elkhorn Slough watershed. Agricultural runoff has led to high concentrations of
nutrients and some pesticides in the slough. Several studies have shown that agricultural
practices have an impact on the species composition and ecological processes in Elkhorn Slough.
Two sites within the slough water are being monitored. One site (SM) is in the Reserve at the
edge of the channel next to a Salicornia sp. marsh that is surrounded by a mixture of native and
introduced grasses and shrubs in the uplands. This is a relatively pristine location with
minimal inputs of agricultural runoff. Azevedo Pond (AP), the second site, is surrounded by
strawberry fields with a very narrow (about 3 m) fringe of marsh. The farm surrounding the pond
is part of a project to develop best management practices and new growing
techniques.

SUPPLEMENTAL INFORMATION:
Associated researchers and projects Elkhorn Slough National
Estuarine Research Reserve and the Elkhorn Slough Foundation have had an ongoing program to
monitor estuarine water quality in the central Monterey Bay region since 1988. Currently, 24
stations are monitored monthly for temperature, salinity, dissolved oxygen, pH, turbidity,
nitrate, ammonium and dissolved inorganic phosphate concentrations. Two of these stations on the
Reserve are about 400 m from the SM site. Data collection began at these two stations in
September 1989. A monthly monitoring station is also located at Azevedo Pond within 10 m of the
YSI deployment. Monthly data from the Azevedo Pond are available from March 1992. The University
of California Santa Cruz Agroecology Program has an ongoing project to examine the effects of
agricultural production on an adjacent wetland. Matthew Werner, Marc Los Huertos, Felecia Rein,
Sean Swezey, Mark Silberstein, Andrew De Vogelaere, Ron Tjeerdema have been the principal
investigators. They have made a detailed baseline characterization of wetlands and an adjacent
field under chemically-intensive strawberry production. The Monterey Bay Regional Studies
Program at UCSC awarded graduate fellowships to Marc Los Huertos and Felecia Rein to study the
effects of native vegetation buffer zones on movement of sediment and agricultural run-off. The
overall goals of this program are to test alternative farming practices that can mitigate
negative effects on wetlands while providing a sustainable livelihood for farmers. This research
is occurring on the Azevedo Ranch in a pond and pocket marsh adjacent to the AP YSI deployment
site. Other remarks/notes

CURRENTNESS REFERENCE:
Observed

SPATIAL DATA ORGANIZATION INFORMATION:
Indirect Spatial Reference: Site location and character Elkhorn Slough is located on the West
Coast of the United States in Central California. It connects with the Pacific Ocean in central
Monterey Bay near Moss Landing, California. The Elkhorn Slough National Estuarine Research
Reserve encompasses about 1400 acres on the south and east side of the slough. A range of
habitats is represented from uplands of oak and grassland, to saltmarsh, tidal mudflat, and open
water. The tidal range in Elkhorn Slough is approximately 2 meters. Annually, surface salinity
varies between 4.2 - 40.5 psu at the head of the slough, between 15.4 - 34.7 psu in the mid
region and between 14.5 - 34.0 psu at the mouth. Elkhorn Slough is a seasonal estuary with the
major freshwater inputs during the winter rainy season. Carneros Creek empties into the head of
the slough and has significant flow between December and April. Periodic freshwater inputs from
the Salinas River to Elkhorn Slough occur when the mouth of the Salinas River is closed and flow
is diverted through the old channel which empties into the mouth of Elkhorn Slough.YSI
datasondes are deployed at two sampling sites: South Marsh (SM) and Azevedo Pond (AP). SM (36�
49N, 121.44W) is in a side channel of the slough on the Elkhorn Slough
National Estuarine Research Reserve. The major runoff to this site is from grasslands and
uplands on the Reserve and is relatively unimpacted by anthropogenic influences. Water depth at
this site is approximately 2 meters and bottom sediments are silty-clays. The adjacent
intertidal mudflats are often colonized by macroalgae such as Ulva and Enteromorpha. AP (36�
50 N, 121� 45 W) is in a pond which receives fertilizer and pesticide
runoff from a strawberry field in year-round production. The YSI is located about 10m from a
culvert connecting the pond to the slough. Two culverts restrict the tidal range within the pond
to 0.5 m. Water depth of the sonde is approximately 1 meter. Bottom sediments are mainly organic
rich silts. Extensive mats of macroalgae (Ulva and Enteromorpha) occur within the pond.