Cayuga Lake Modeling Project

Update

March 2016

Liz Moran, EcoLogic

Photo: Bill Hecht

• Description of the Cayuga Lake Modeling Project

– Relation to Lake Source Cooling permit renewal

– Project team

• Findings to Date: Cayuga Lake

– Sources of phosphorus and bioavailability

– Water circulation (hydrodynamics)

• Watershed Model Status

• Major Findings and Next Steps

Presentation Outline

March 2016 2

• Description of the Cayuga Lake Modeling Project

– Relation to Lake Source Cooling permit renewal

– Project team

• Findings to Date: Cayuga Lake – Sources of phosphorus and bioavailability

– Water circulation (hydrodynamics)

• Watershed Model Status

• Major Findings and Next Steps

Presentation Outline

March 2016 3

Photos, illustrations, graphics here.

Cayuga Lake Modeling Project (CLMP)

• Scientific investigation of sources of phosphorus to Cayuga Lake and the consequences for phytoplankton growth

• Does not model aquatic plants (macrophytes)

• Included as a permit requirement for operation of Cornell’s Lake Source Cooling (LSC) facility

March 2016 4

Why investigate the sources and impacts of

phosphorus in Cayuga Lake?

• Phosphorus is the limiting nutrient for phytoplankton growth

• In 2002, DEC listed southern Cayuga Lake as impairedby excessive phosphorus and silt/sediment

– Impaired relative to a designated “best use”

– In 2008, southern lake listed for pathogens, delisted in 2014 based on City and CSI data

• Once southern Cayuga Lake was listed as impaired, DEC was required to act

– Identify and quantify the source(s) of impairment

– Identify strategy for improvement- TMDL or other

March 2016 5

4- Class A

3- Class AA (T)

1- Class BNYSDEC classifies Cayuga Lake in four

distinct segments, depending on “best

use”, and habitat suitability for salmonids,

designated by (T)2- Class A(T)

6

Best Use: AA A B

Water supply- minimal

treatment

Water supply-

coagulation & filtration

Water contact

recreation

Fishing

Fish, shellfish &

wildlife propagation

and survival

March 2016

March 2016 7

• Southern shelf listed as impaired due to occasional

exceedances of DEC’s Total P guidance value – 20 µg/L

summer average

• Guidance value selected to protect recreational uses in

Class AA, A, and B lakes from excessive algae

(phytoplankton)

• Sediment not a direct focus of CLMP, only as it

contributes to biologically-available P and affects water

clarity

CLMP focuses on Phosphorus (P) and Algae

• LSC draws cold water from deep in the lake—segment

3, circulates it through a shoreline heat exchange facility,

and returns water (slightly warmed) to segment 4

• No phosphorus is added

• Assuming that deep & shallow lake waters do not

naturally mix during summer, DEC considered LSC a

point source of phosphorus to segment 4 (the shelf)

Why is the CLMP included as a permit condition for

operation of the LSC facility?

March 2016 8

The Lake Source Cooling Process

March 2016 9

Environmental Benefits of the LSC Facility

• Renewable resource

– Decreased reliance on fossil fuels & reduced adverse impacts,

including greenhouse gases

• Energy efficiency

– 86% reduction in energy used for cooling of campus and

Ithaca High School

• Reduced demand on electrical grid

– 25 million kW hrs/year

– Reduced load at peak demand periods

March 2016 10

• CLMP represents a significant investment in research

and modeling

• Integrate science into policy decisions for managing

Cayuga Lake and other lakes

• Holistic evaluation of all the sources of P and how they

affect the lake

• Apply the emerging ecosystem-based management

approach that considers impacts on water, air, and lands

Opportunities to Advance Science and Policy

March 2016 11

Elements of the CLMP

• Phase 1: Monitoring (April 2013 – Oct 2013)– Project plan reviewed and approved

– Testing streams, lake, point sources

– Lake biological community- mussels and plankton

– Measure bioavailability of phosphorus fractions

• Phase 2: Modeling (Jan 2014 – Dec 2016)– Lake model: water circulation (hydrodynamics) and water

quality, focus on phosphorus and algae

– Watershed model: effects of land use, land cover, and hydrology on phosphorus flux

March 2016 12

March 2016 13

Project PartnersNYSDEC

Cornell University

Utilities & Energy Management

Upstate Freshwater Institute

(Monitoring and Lake Model)

Cornell BEE

Soil & Water Lab

(Watershed Model)

Faculty Advisors

Technical Advisory

Committee

USEPA

Model Evaluation

Group

Oversight & Approvals

Project Management

and Funding

Model Developers

• Description of the Cayuga Lake Modeling Project

– Relation to Lake Source Cooling permit renewal

– Project team

• Findings to Date: Cayuga Lake – Sources of phosphorus and bioavailability

– Water circulation (hydrodynamics)

• Watershed Model Status

• Major Findings and Next Steps

Presentation Outline

March 2016 14

• Phosphorus fractions (dissolved, particulate, etc.) differ in

bioavailability, i.e., the ability to support algal growth

• Detailed monitoring and analysis in 2013 reveal that nearly all

bioavailable phosphorus entering Cayuga Lake came from

watershed nonpoint sources (97%), not point sources (3%)

• Elevated total phosphorus concentrations are associated with

sediment particles (mud) that enter the lake during runoff events,

and the mud has low bioavailability

• Lake circulation is complex and dynamic, with significant mixing

between the southern shelf and the main lake

Findings to Date (March 2016)

March 2016 15

April – October 2013

Bioavailable P Inputs, Shelf and Lake-wide

Tributaries

97%

6 Treatment

Plants

3%

Bioavailable P Load to

Cayuga Lake: 13.8 mt

Tributaries Treatment Plants

Tributaries

87%

LSC recirculation

6%

2 Treatment

Plants

(IA,CH)

7%

Bioavailable P Load to

Shelf: 3.4 mt

Tributaries

LSC (recirculation)

Treatment Plants

(IA,CH)

March 2016 16

TP

(µ

g/L

)

0

10

20

30

40

Jun Jul Aug Sep

Q (

m3/s

)

0

20

40

60

80

100

Runoff delivers sediment “mud” to the shelf, but

phosphorus (PP m/u) in mud is very low in

bioavailability

hydrology

cases

of interest

dry weather (base flow)runoff events

dry weather runoff events summer average

s – shelf

ml- main lake

s ml s ml sml

PPm/u wet

summer

case

March 2016 17

Green- total dissolved P+ particulate organic P

Red- particulate inorganic P (mud)

All fractions contribute to Total P (TP)

2013

Sediment Plume from Taughannock Creek

Photo: Bill Hecht

March 2016 18

Complex Lake Circulation Patterns

Photo: Bill Hecht

March 2016 19

March 2016 20

Wind-driven circulation brings deep water onto the

shelf

Natural mixing processes prevent development of

higher phytoplankton biomass on the shelf

shelf

mixing

local loads

“Flushing rate of the shelf from mixing is rapid relative to phytoplankton growth rates”

(Effler et al. 2010, Gelda et al. 2015a)

Recent upgrades to the Cayuga Heights and Ithaca treatment plants reduced bioavailable P load by ~80% from those point sources with no response in algae.

This is attributed to the rapid flushing of the shelf from natural mixing processes.

March 2016 21

March 2016 22

Chlorophyll-a Concentrations (Measure of Algae)

are Comparable at Shelf & Main Lake Stations

0

2

4

6

8

10

12

14

16

Ch

loro

ph

yll

-a, u

g/L

Shelf Main Lake

• Description of the Cayuga Lake Modeling Project

– Relation to Lake Source Cooling permit renewal

– Project team

• Findings to Date: Cayuga Lake – Sources of phosphorus and bioavailability

– Water circulation (hydrodynamics)

• Watershed Model Status

• Major Findings and Next Steps

Presentation Outline

March 2016 23

March 2016 24

• Estimate phosphorus loads

from the watershed

– Inform lake model inputs

• Provide a tool to test

management (“what-if”)

scenarios

Objectives of the Watershed Model

Model Choice and Rationale

Soil Water Assessment Tool (SWAT)

Developed by USDA-ARS, Texas A&M

Widely used in TMDL-type projects

Simulates dissolved & particulate P

Soil & Water team experienced

with SWAT model

Adaptable to local conditions

Flexible management input

Goog

le Im

ages

4

March 2016 25

Dave

Bouldin

CSI

26

Photos, illustrations, graphics here.

March 2016 27

Land Use/Land Cover Affect

Phosphorus Export

• Streams draining

agricultural areas have

higher phosphorus

concentrations

• Forested landscapes

have much lower

phosphorus loss

% Forest

% Agriculture

Tota

l P

(m

g/L

)

100%

100%0%

0%

0.00

0.30

Lyon, Walter, et al. 2006. JAWRA. 42(3): 793-804

Watershed Model Data Needs

• Fraction of agricultural lands managed by

larger farms vs. smaller farms

• Rate of application of manure

• Frequency and timing of manure application

per managed unit (field)

31

March 2016 28

• Soil and Water Conservation Districts

• Ag & Markets / Pro-Dairy

• NYS Soil and Water Conservation Committee

Manure Management: Data Sources

March 2016 29

March 2016 30

• CAFO (350 cows)- Manure storage – Apply to row crops (e.g., corn) in May and October

– Apply to hay lands in May and October

– Some hay lands may receive manure in other months

• AFO (Fewer than 350 cows)– Apply to row crops in May and October

– Apply to hay lands year round; one annual spread per field

• Overall, 30% of hay lands receive manure in any one year

Manure Management: Detailed Findings

1990

Fal

l C

reek

Dis

char

ge,

m3/s

ec

March 2016 31

1978

Some Total Phosphorus ResultsT

ota

l P

ho

sphoru

s, k

g/d

ay

March 2016 32

Fall Creek Phosphorus Export

Detailed analysis:

• Soils

• Slopes

• Wetness factor

• Land cover

• Agricultural practices

including manure

disposal

March 2016 33

Scenarios

• Current conditions

• Hindcast: What were sediment and phosphorus loads pre-settlement (1700s)?

• Management:

– Turn off individual sources

– Implement agricultural Best Management Practices

• Change the timing of manure applications ~ avoid forecasted rain

• Change the placement of manure ~ buffers around concentrated flow paths

• Other recommended practices ~ cover crops, swales

• Forecast: Potential changes in a future climate

March 2016 34

Looking Ahead

• 2016

– Lake eutrophication model

– Watershed model

– Linkage between lake and watershed models

– Models delivered to NYSDEC for their use

• 2017

– NYSDEC will develop TMDL for southern Cayuga, or identify other effective water quality strategies

March 2016 35

• Description of the Cayuga Lake Modeling Project

– Relation to Lake Source Cooling permit renewal

– Project team

• Findings to Date: Cayuga Lake – Sources of phosphorus and bioavailability

– Water circulation (hydrodynamics)

• Watershed Model Status

• Major Findings and Next Steps

Presentation Outline

March 2016 36

• The shelf is not a separate manageable water body

• Tributary streams (watershed) are the overwhelming

source of bioavailable phosphorus

• Extensive monitoring data indicate that Cayuga Lake

water quality is consistent with a mesotrophic

(healthy) condition with no trend to degradation

• Lake clarity is reduced after storms by sediment, not

algae

Major Findings to Date

March 2016 37

• Watershed model will provide quantitative tool for assessing phosphorus sources and potential reductions

• Watershed model to inform lake model- what is the impact of potential reductions?

• Opportunity to apply this detailed knowledge to the Watershed Management Plan update now underway

– 20+ scientific papers from UFI and Soil & Water Lab

– Potential to apply CLMP knowledge far beyond Cayuga watershed

Next Steps

March 2016 38

www.cayugalakemodelingproject.cornell.edu

All Reports, Presentations, Technical Papers and Data

are on the Cayuga Lake Modeling Project Webpage

March 2016 39

Thank You

Questions and Discussion

March 2016 40