Quantifying nitrogen loading from land to sea in Nassau County

Many impairments associated with nitrogen overload

Impaired

Minor impacts

No known impacts

Salt marsh ecosystems

Salt marshes protect coastlines

Salt marshes protect coastlines

Flooding during Hurricane Sandy

“Coastal eutrophication as a driver of salt marsh loss”, Deegan et al 2012, Nature

Healthy marsh Nitrogen loaded marsh

Nutrient Dense, weakened, strong roots roots

Loss of wetlands on Long Island, since 1974 90

80

Per

cen

t lo

ss s

ince

19

74

NYSDEC survey data 70

60

50

40

30

20

10

0 So

uth

Man

hasset B

ay

Man

hasset, M

ano

r Hav

en

Man

hasset, P

lum

Po

int

Man

hasset, K

ing

s Po

int

Peco

nics, C

orey

Creek

Mou

nt S

inai H

arbo

r

Flax

Pon

d

Sto

ny B

rook

Harb

or

Nisseq

uog

ue R

iver

Western

Bay

s, East B

ay

Western

Bay

s, Mid

dle B

ay

So

uth

Oy

ster Bay

, Go

ose Is.

So

uth

Oy

ster Bay

, Gilg

o Is.

Peco

nics, C

edar B

each C

reek

Suffolk County, North Shore

Nassau County, North Shore Suffolk County Nassau County

East end South Shore South Shore

Seagrass: Critical habitat

for fish and shellfish

NYS seagrass, 1930 - 2030 200,000

150,000 A

cres

of

seag

rass

100,000

50,000

0 Extinction in NY

1930 2009 2030

NYSDEC Seagrass Taskforce Final Report, 2010; Suffolk County assessment, 2014

Nitrogen promotes in the water impairments: algal blooms, low oxygen

Point Lookout, seaweed bloom: unsightly, contributes to low oxygen, low pH

Percent bottom coverage of Ulva sp. in Western Bays in the Fall of 2011.

Jones Inlet

Effects of nutrients on the growth of Ulva in the Western Bays

Control N P Si

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Ne

t gr

ow

th r

ate

, d⁻¹

Excessive nitrogen loading can leads to low

Nitrogen loading

Phytoplankton

CH2O + O2 Respiration

CO2 + H2O Consumed Produced

“More algae and warm temperatures during summer make bacteria hyperventilate”

Minimum dissolved oxygen, summer 2016

= Good = Fair = Poor

Good: DO minimum > 5 mg/L Fair: DO minimum 3 – 5 mg/L Poor: DO minimum < 3 mg/L

NYS landings of shellfish, 1980 – 2010

-100 -90 -80 -70 -60 -50 -40 -30 -20 -10

0

Perc

ent

dec

line

sin

ce 1

98

0

Clams Oysters Scallops Mussels

Losses due to nitrogen driven harmful algal blooms, seagrass loss, and water quality degradation.

Has nitrogen mitigation helped hypoxia in Long Island Sound?

• Goal to reduce N loads by 58.5% • In 2014, close to reaching this goal. • Ecosystem response?

Reduction in Long Island Sound hypoxic area with 60% nitrogen reduction

Squ

are

mile

s o

f h

ypo

xia

(<2

mg

/L)

200

180

160

140

120

100

80

60

40

20

0

R² = 0.4627

2002 2004 2006 2008 2010 2012 2014 2016 2018

Planned re-routing of Bay Park sewage to Cedar Creek ocean outfall

Potential recovery of seagrass in Western Bays

Potential gain of nearly 3,000 acres of seagrass with sewage abatement.

Nitrogen Loading Model (NLM) components:

Atmospheric

Deposition

Fertilizer

Wastewater

Total N Load

How much nitrogen?

What is the source?

Nitrogen Loading Model (NLM) Overview:

Source: Latimer and Charpentier 2010

Nitrogen Loading Model (NLM) Overview:

13 Nassau County watersheds

Base Layers created:

Tax map and census identification of all

properties: Lot size, number of individuals

per home, size of buildings.

Lawn raster

Impervious raster

Lawn Raster High Resolution Normalized Difference Orthoimagery Vegetation Index > 80

Lawns

Where both

are true

LiDAR Object Height < .1m

Impervious Raster

High Resolution Normalized Difference Impervious

Orthoimagery Vegetation Index < 90

Atmospheric Deposition

N-Load from

Atmospheric

Deposition

Natural

Vegetation

Turf

Agriculture

Ponds

Wetlands

Roads

Residential

Impervious

Other

Impervious

Residential + Golf + Park Lawns

All area that is not included

below

Land Use Data

Land Use Data

Land Use Data

?

Impervious limited to Residential Parcels

Impervious total – Road – Res Impervious

Fertilizer

N-Load

from

Fertilizer

Agriculture

Residential

Lawns

Golf Lawns

Park Lawns

Land Use Data

Lawns limited to

Residential Parcels

Lawns limited to Golf

Course Parcels

Lawns limited to Park

Parcels

Wastewater

N-Load

from

Wastewater

Cesspools within

200m of shore

Cesspools outside

200m of shore

Septic systems within

200m of shore

Septic systems outside

200m of shore

Sewer Plants N Output

# of People

2010 Census

# of People

2010 Census

# of People

2010 Census

# of People

2010 Census

Lloyd Aquifer

Raritan Clay Confining Unit

Upper Glacial Aquifer

Water Table

Magothy Aquifer

Agriculture

Stream

Loading Rates (lb-N/A/yr)

Pasture/Hay: 20

Orchards: 70

Vineyards: 15 Sod: 250

“Other”: 110

40%

Atmospheric Deposition

0.04 lbs-N/1,000sf/yr

Leaching:

25% natural

30% turf

40% agriculture

Fertilizer inputs: Agriculture

Lloyd Aquifer

Raritan Clay Confining Unit

Upper Glacial Aquifer

Water Table

Magothy Aquifer

Parks/Golf

Courses

Stream

Atmospheric Deposition

0.04 lbs-N/1,000sf/yr

3.89 lbs-N/1,000sf/yr

20%Leaching:

25% natural

30% turf

40% agriculture

Fertilizer inputs: Parks, golf, homes

Homes2.5 lbs-N/1,000sf/yr

30%

Lloyd Aquifer

Raritan Clay Confining Unit

Upper Glacial Aquifer

Water Table

Magothy Aquifer

Residential

(unsewered)

Stream

Loading Rates

10 lbs-N/person/yr

U.S. Census Data

6% removal from tank

10% removal in “plume”

Atmospheric Deposition

0.04 lbs-N/1,000sf/yr

Leaching:

25% natural

30% turf

40% agriculture

Wastewater: residential

Lloyd Aquifer

Raritan Clay Confining Unit

Upper Glacial Aquifer

Water Table

Magothy Aquifer

Commercial

Stream

Atmospheric Deposition

0.04 lbs-N/1,000sf/yr

Leaching:

25% natural

30% turf

40% agriculture

Commercial:

0.07 gpd/sf x 60 mg/L

+ 2 residential units in

downtown areas

Industrial:

0.04 gpd/sf x 60 mg/L

Institutional:

0.06 gpd/sf x 60 mg/L

Wastewater: commercial

Sewage treatment plants: Wastewater (treatment facilities): Flow and concentration data for sewage

treatment plants subwatersheds. Averaged across years. Source NYSDEC or

EPA- ECHO.

Missing Data

The model is 90% done. Outstanding needs include.

Freshwater wetlands: Publicly available shapefile is clearly wrong.

Sewersheds for Suffolk and Queens Counties (some of the watersheds of Nassau extend into these counties).

Outfall Locations of Sewer Plants (Not facility location)

Roads: The shapefile available is for roads only has two categories: Local and Secondary. It would be nice to get a shapefile with more divisions, but maybe this is not necessary.

Next steps

Apply residence times to nitrogen loading rates to determine

nitrogen residence times.

Compiled water quality data from across the north and south shore

to compare to nitrogen residence times.

Rank watersheds?