CARTI Presentation April 2010 1

Salt in Dutchess Co Waters –Where, when, so what?

Stuart Findlay and Vicky Kelly – Cary Institute of Ecosystem Studies

Don Siegel and Li Jin – Syracuse University

Some Chloride Reference Points• Background - ~ 10 mg/L or less [Catskill Reservoirs]

• Sublethal – 50-100 mg/L Subtle yet Significant

– Biotic Indices

– Microbial processes

– Associations

• EPA Chronic – 230 mg/L

• Drinking Water Std – 250 mg/L

• EPA Acute – 860 mg/L

• Lethal - 1000 or higher

SIMPLER

• REFERENCE <10 mg/L

• ENVIRONMENTAL EFFECTS ~ 100 mg/L

• LETHAL > 1000 mg/L

DUTCHESS COUNTY WATERS80 mg/L (+/- 79 SD)

Ten Mile10-40

Crum Elbow15-50

Casperkill100-300(Cunningham et al 2009)

Dutchess CountyChloride(mg/L)

Wappinger10-45

Fishkill10-100

Mullaney et al., USGS

DC WC

CARTI Presentation April 2010 6

Karraker et al. 2008

CARTI Presentation April 2010 7NaCl (mg/L)

0 10000 20000 30000 40000 50000

Pe

rce

nt

Su

rviv

al

0

20

40

60

80

100

120

AdultEmbryo

THE UNEXPECTED

• Long-term increases in concentration

• High concentrations in summer

• Higher concentrations downstream (in summer)

Long-term IncreaseSaw Kill Creek

HRNERR• Low-density residential

• Yearly mean Cl-

concentrations have doubled since 1991 (20 to 40 mg/L)

• Similar Cl- concentrations throughout year

Year

1990 1992 1994 1996 1998 2000 2002 2004

Chl

orid

e (m

g/L)

0

10

20

30

40

50

60

High concentrations

in summer

0

20

40

1 2 3 4 5 6 7 8 9 10 11 12

MONTH

CH

LOR

IDE

(mg/

L)

East Branch Wappinger Creek, Millbrook

No decline in summer concentrations

DISTANCE FROM MOUTH (km)

0 5 10 15 20 25 30 35

Chl

orid

e (m

g/L)

0

20

40

60

80

100

120

140

160

FISHKILL CREEKSummer 2005

Popul

atio

n

New York State

Downstream increases insummer

HeadwatersMouth

Groundwater / Surfacewater

05

1015202530354045

25 50 75 100 125 150 175 200 225 More

Chloride (mg/L)

% o

f Sam

ples

WELL

SURF

Fig. 4: Frequency distribution of chloride concentrations in surface and well samples from Dutchess County.

A few wells have Cl > surface water concentration – Could support high baseflow concentrations

Private drinking-water wellsNon-random but widely distributed

Residential Land Cover and Chloride (M. Essery)

Subwatersheds in the Fishklill Basin

Percent Residential

5 10 15 20 25 30 35 40 45

Chlo

ride (

mg/L

)

20

40

60

80

100

120

140

160

180

200

220

Sources of Chloride(% of flux in Fishkill Creek)

(>80%)

(~1%)

(5-10%)

CHLORIDE IS NOT ALONE – ASSOCIATED WITH

OTHER CONTAMINANTS

0 30 60 90 120 150 180 210

CL (mg/L)

0

4

8

12

16

20

24

NO

3 (

mg/L

)

D. Burns - EMC

Event – Dec 24-27, 2008Fishkill Creek at Beacon

Exposure at “peak” concentration equivalent to about twice as long at “baseline” concentration

An Engaging Problem?• Everyone understands “salt”-opportunity for

education

• Not viewed as a threatening issue -not (presently) a health hazard or regulated material

• Point sources don’t always seem to be the problem (no finger-pointing, low media attention)

• Chloride is associated with nitrate so trend may suggest presence of other contaminants

The Future? Scenario Tests• Scenario 1--Reducing road salt application by half

– Cl decreases up to 20.7% at mouth

• Scenario 2- --Doubling road salt application– Cl increases up to 34.2% at mouth

0

20

40

60

80

100

120

06/01/08 08/31/08 11/30/08 03/01/09 05/31/09

Cl c

once

ntr

atio

ns (

mg/

L)

Modeled Cl

Scenario1 Cl

Scenario2 Cl

Fishkill Creek Reach 7 (mouth)

Base

-50%

2X

Jin et al. 2011