Elkhorn Slough Water quality Programs Trends and Concerns

ESNERR WQ Monitoring Program-Volunteer SitesSample Monthly 1989 – Present

Params by Probe (DO,Temp,Sal,pH,Turb, Chl) & Nutrients (Nitrate, Phosphate Ammoinium)

ESNERR WQ Monitoring Program-NERR SitesSample every 15 mins; 1995 (AP & SM) – Present

Params by probe (Depth, DO,Temp,Sal,pH,Turb) & Monthly Nutrients (Nitrate, Phosphate Ammoinium)

Even the mouth of the Estuary goes below the 5 mg/L target

As we move up the slough DO gets worse and worse

Azevedo Pond below 5 mg/L almost year round, hypoxic <2.3 mg/L summer and fall

Nutrient pollution varies by region

Salinas River sites Annual Average 2002-2009

Nitrate concentrations mg NOx/LComparison of means of all available data by Reserve and Station, 2006–2011

OWC takes the prize highest average nitrate NERR range .02 – 2.7 mg/L

Nitrate concentrations mg NOx/LComparison of means of all available data by Reserve and Station, 2006–2011

Salinas River Sites Average 22 mg/L 10X higher than Highest NERR site in Country

Chl by tidal exchange in the EstuaryLow Moderate High Hyper

EUTROPHICATION: anoxic sedimentA much narrower layer at the top of the mud is well oxygenated at muted vs. full tidal sites

EUTROPHICATION: dissolved oxygenGreater variation with less tidal exchange

a

b

b

a

b

b

Nitrate

0

100

200

300

400

500

600

700

800

900

70 72 74 76 78 80 82 84 86 88 90 92 94 96 98

µM

0.001 0.01 0.1 1 10

JOBRKBGTMSAPGNDNARACENIW

WQBNOCKACELKGRBJACCBVSOSTJR

SFBAPAWKBCBMHUDPDBDEL

WELOWC

mg NOx L-1

How different are the NERR sites?

http://nerrs.noaa.gov

Comparison of means of all available data by Reserve and Station, 2002 – 2006/7

Annual Hypoxia from two NERR stations

AVIRIS photo, John Ryan, MBARI

Azevedo Pond

South Marsh

Data from Ken Johnson 2010

0

10

20

30

40

50

60

70

80

0 0.5 1 1.5 2 2.5 3 3.5

% T

ime

Hyp

oxic

(<

28%

Sat

urat

ed D

O)

Maximum Tidal Range (m)

Bennett Slough 1

Bennett Slough 2Moss Landing Harbor

Moro Cojo Slough

Elkhorn Slough 1

Elkhorn Slough 2

ES5ES4ES3

ES @ Kirby

Figure 5. Maximum tidal exchange v. % time hypoxic

Tidal range vs % time hypoxic

How different are the NERR sites?

http://nerrs.noaa.gov

Comparison of means of all available data by Reserve and Station, 2002 – 2006/7

g Chl a L-1

NARKACJOBSOSJAC

GTMRKBHUDNOCPDBGRBGNDSFBNIWSAPAPAELKTJR

CBVMARACE

WQBDEL

OWCCBMWKBWEL

0.1 1.0 10 100

Summary take home messages