LINKING LAND INPUTS TO ESTUARINE LINKING LAND INPUTS TO ESTUARINE WATER QUALITY TRENDS

Joint Meeting: Tidal Monitoring and Analysis Workgroup and

Nontidal Water Quality Workgroupy g p27 March, 2013

USGS Baltimore Science Center

Walt Boynton and ColleaguesCenter for Environmental ScienceChesapeake Biological LaboratoryChesapeake Biological Laboratory

Solomons, MD 20688

Understanding dTrends

BMPs

e

…that’s what did it!

DO Failure Rate

All that ecology stuff and

everything else

Time

D

• Document trends for relevant variables

• UNDERSTAND the cause(s) of the trend(s)

• Relate trend(s) to BMPs…the effects of management…and everything else

Conceptual Models Used to Organize the Analysis: A l f An example…one of many

From: Boynton et al 1982

SIMPLE RELATIONSHIP LINKING LAND AND ESTUARY

Patapscoy = 2 1 + 0 13x

LAND AND ESTUARYm

-2 6

8Patapscoy = 2.1 + 0.13x

r2 = 0.98Mass of N in mesohaline regions

proportional to loading rate

• Data from multiple sub-systems

TN M

ass,

g N

m

4 Patuxent

MD Mainstem Chesapeake

Potomac

Potomac River Estuary

mg

l-1

1 4

1.6

1.8

r ² = 0.88

Data from multiple sub systems of the Bay

• Analysis done on annual time-scale

T

2

Choptank

20 25 30 35 40 45 50 55 60

Ann

ual A

vera

ge T

N,

0.4

0.6

0.8

1.0

1.2

1.4

TN Load, g N m-2 yr-10 10 20 30 40 50

0TN Loading, g N m-2 yr-1

20 25 30 35 40 45 50 55 60

N and P loading rates and Changes in Loading Rates: Several from Chesapeake Bay systems and we many more CB sites can be added

MattawomanPristine Condition

The Scaling Processg• Assemble data sets

U i t l d l id • Using conceptual model as a guide to explore data for chlorophyll-a relationships

• Examine “residuals” from initial analyses and add variables as needed to improve relationship

• In an on-going analysis we are conducting 20 different CB estuaries are included, each with a time-series of 19 years

Boynton and Kemp 2000

Preliminary Product: l “ l d l d hl h ll l hA simple “scaled” nitrogen load vs chlorophyll-a relationship

µg l-1

120

140

160 Shallow Ches Bay tributaries

Mattawoman Ck (2005-2010)Mattawoman Ck (1985-1988)

Best Fit Regression95% Confidence Interval

hlor

ophy

ll-a,

80

100

120

MattawomanSAV Nutrient Load 

Threshold

May

-Aug

Ch

40

60

0.0 0.1 0.2 0.3 0.4 0.5

M

0

20

Jan - Mar TN Load, g N m-2 day-1

Southern New England SAV Nutrient Load Threshold

350

Examples of WWTP Load Reductions: Back Riverd,

kg

P/d

ay

250

300

350

Phosphorus

nt S

ourc

e D

IP L

oad

100

150

200

Poi

n

0

50

8000• Good engineering works!

N

oad,

kg

N/d

ay

6000

• P loads very reduced.

• N loads also reduced.

Nitrogen

Poi

nt S

ourc

e TN

Lo

2000

4000

•TSS and BOD5 also greatly reduced

years

1985 1990 1995 2000 2005

P

0

Chlorophyll – Nutrient Load Relationship

• Strongest relationship between nutrients and Chl-a was with NITROGEN

• All strong relationships g pinvolved multi-year averaging (2-3 yrs)

• Time lags between load changes and response were important…there is a nutrient memory

f hl • Significant Chl-a reduction was achieved (~50%)

Trends and Analysis: Mattawoman Creek Case Study

• Major reduction in N and P loads

• Several year delay in responses

Chl h ll d li d (4X) l it • Chlorophyll declined (4X), clarity improved (2.5X) and SAV exploded

• Appeared to be a threshold ppresponse for SAV (< 18 ug/l chlorophyll)

SAV ThresholdMajor WWTP

Load Reduction

Another Threshold Example: SAV recovery in upper Patuxent River

ha

This section of Patuxent

Coverage, h

Strong management action – WWTP N‐removal SA

V C

NO23 Concentration, mg/l (May – July)

Here’s another conceptual model: Winter factors of wind, flow and n t i nt l ds pl k l in d t minin th xt nt f s mm nutrient loads play a key role in determining the extent of summer hypoxia….summer winds tend to reduce the duration and intensity of hypoxia

W Sp Su F W S S F

Annual-Scale Chesapeake Bay Hypoxia

Wind from N – E 

W‐Sp Surface Chlorophyll‐a

Surface Dissolved Oxygen

W  Sp  Su  F W  Sp  Su  F

Winter Wind

Summer Wind

Geographic positioning of spring bloom

most important

Pycnocline

W  Sp  Su  F

River Flow

Dep

osition

W‐Sp Bottom Chlorophyll‐a

Bottom Dissolved Oxygen

Sediments

W  Sp  Su  F

Nitrogen Load

Deep water respiration

CB Hypoxia (June-Sept) and Controlling Features: 1985 - 2007

Lee etal 2012

The Chesapeake Bay appears to have become a SOURCE The Chesapeake Bay appears to have become a SOURCE rather than a SINK for DIN…nutrients are now entering the Patuxent from both ends. A New TREND

y-1

ge, K

g N

day

DIN

Exc

hang

Net

D

Time, years since 1985

(From Testa et al 2008)

Understanding and Forecasting: Rockfish example

Day of peak Zooplk concentration

The Beginning The End

Martino and Houde 2010

Next StepsNext Steps• C ti d t bl d l i f t d i l • Continue data assembly and analysis of trends, mainly N, P, flow and sediment loading from the basins

C ntinu st tistic l ( nd simul ti n) m d lin usin • Continue statistical (and simulation) modeling using conceptual models as guides

• Add variables to the models as needed but keep • Add variables to the models as needed but keep models as simple as possible for tractability and explainability

• Look for examples other than those related to WWTP load reductions (e.g., Murphy et al).

Physical characteristics of basins and estuaries: arranged from smallest to largest basins

Estuary Basin Area  

Estuary Volume 

Estuary Surface Area

Average Depth  

Max Depth 

max depth: average 

mouth length  

shoreline length  

shoreline: mouth  

Basin Area: Estuary Area

Basin Area: Estuary 

Area depth 

Area Volume

m2*106  m3*106  m2*106  m  m  m  m  1/m 

Middle  33  16  10  2  3  2  6091  59763  10  3  2 WestRhode  66  24  15  2  4  3  4243  34110  8  4  3 Magothy  94  60  20  3  11  4  3998  35175  9  5  2 Corsica  97  10  5  2  5  3  1501  22458  15  18  9 Bohemia  131  28  14  2  6  3  1854  35793  19  9  5 Back  144  57  29  2  5  2  1443  32878  23  5  3 South  148  78  24  3  9  3  2936  48513  17  6  2 

Piscataway  176  4  4  1  1  1  1199  10963  9  48  47 Severn  177  154  40 4 8 2 3319  49876 15 4 1

Northeast  184  19  16  1  4  3  2294  20503  9  11  10 Sassafras  217  155  36  4  10  2  5541  51045  9  6  1 

Mattawoman  245  26  22  1  5  4  1607  29572  18  11  9 Bush  336  53  27  2  6  3  2513  46909  19  13  6 

Wi i 561 49 21 2 8 3 2757 53491 19 27 11Wicomico  561  49  21 2 8 3 2757  53491 19 27 11Gunpowder  1181  66  36  2  11  6  3392  50842  15  33  18 Patapsco  1518  469  101  5  11  2  8026  97541  12  15  3 Pocomoke  1672  19  7  3  8  3  14214  91697  6  243  90 Choptank  1951  1348  361  4  25  7  20554  239797  12  5  1 Patuxent 2343 652 137 5 36 8 2033 160597 79 17 4Patuxent  2343  652  137 5 36 8 2033  160597 79 17 4

Rappahannock  6918  1753  393  4  23  5  5899  275006  47  18  4  

Hypoxia Duration Linked to Summer AlgaeHypoxia Duration Linked to Summer Algae