Developing a Framework to Advance Statewide Phosphorus Reduction Credits for Leaf Collection

Leaf Collection to Reduce Phosphorus

• Agricultural and urban sources of phosphorus are targeted in the Adaptive Management plan for Rock River TMDL

• Structural practices alone may not be enough

• Leaf collection identified as reasonable measure to reduce Total P delivered to lakes

• Are some leaf collection practices better than others?

Source: Rock River Coalition

2. Develop criteria to rapidlyassess effectiveness of differentleaf collection practices usingfield survey techniques

3. Advance ability to modelP load in urban watersheds and response to management

Study Objectives

1. Collect water-quality samples from a control and test basin to determine if removing leaves will result in detectablechanges in phosphorus [“book end approach”]

All L

eave

s St

ay

All L

eave

s G

one

Study BasinSource Area Control Test

Area (acres) 15.9 3.0

Streets 17% 19%

Driveways 6% 4%

Roofs 17% 19%

Sidewalks 5% 3%

Lawns/Open 55% 54%

Other Impervious <1% 0%

Tree Cover 45% 68%

Control Test

USGS Monitoring Location

Paired Basin Study Design

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0.5

1

1.5

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2.5

3

3.5

April May June July August September October November

Mea

n To

tal P

hosp

horu

s Con

cent

ratio

n, in

mg/

l

Mean total phosphorus concentration during the calibration period in which there wasno leaf collection or street cleaning

Control (2013-2015)

Test (2013-2014)

April May June-Aug Sept Oct Nov

Photo Credit: USGS

Leaf Management Practices

Variables that influence EOP nutrient load:

Photo Credit: USGSPhoto Credit: USGS

• leaf collection method • street cleaning technology • frequency

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3.5

April May June July August September October NovemberMea

n To

tal P

hosp

horu

s Con

cent

ratio

n, in

mg/

l

Mean total phosphorus concentration during the calibration period compared to the treatment period in which there was weekly leaf collection and/or street cleaning

Control (2013-2015)

Test (2013-2014)

Test (Treatment 2015)

Photo Credit: USGS

Seasonal Total Phosphorus Yield as a Percent of the 2015 Annual Yield (winter excluded)

Spring14%

Summer30%

Fall56%

Control (do nothing)

Spring22%

Summer62%

Fall16%

Test (do everything)

Paired Basin Results for Nutrient Load (Log), in grams

Phosphorus Reduction Credits

Madison SOP = 3-4 times/season

City of Madison – Leaf Collection plus Sweeping“Madison SOP, SOP+, and Vacuum-Mulch”

HIGH TREE CANOPYLeaf Collection Street Cleaning

Method Frequency Method Frequency Year Completed Title

Transfer Weekly Mechanical/blower Pre-event 2015 Upper Maximal

Transfer 3-4x Mechanical 3-4x 2016 Madison SOP

Transfer 3-4x Regenerative Air Weekly 2017 Madison SOP+

Vacuum Weekly Regenerative Air Weekly 2017 Vacuum Mulch

Transfer 3-4x None -- 2018 Leaf piles only

Vacuum 3-4x Regenerative Air weekly 2018 Madison SOP+

MEDIUM TREE CANOPYLeaf Collection Street Cleaning

Method Frequency Method Frequency Year Completed Title

Transfer 3-4x Mechanical 3-4x 2018 Madison SOP

Vacuum Weekly Mechanical Weekly 2019 Fond du Lac

Vacuum Weekly Regenerative Air Weekly 2019 Oshkosh

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Change in Phosphorus Load

0

10

20

30

40

50

60

70

80

90

Max SOP+2018

SOP+2017

Vac SOP(HC)

Pilesonly

SOP(MC)

Perc

ent R

educ

tion

Total Phosphorus

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

0

10

20

30

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50

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90

Max SOP+2018

SOP+2017

Vac SOP(HC)

Pilesonly

SOP(MC)

Perc

ent R

educ

tion

Dissolved Phosphorus

Not

sta

tistic

ally

sig

nific

ant

95% Significance

90% Significance

85% Significance

80% Significance

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Change in Nitrogen Load

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

-100

-80

-60

-40

-20

0

20

40

60

80

100

Max SOP+2018

SOP+2017

Vac SOP(HC)

Pilesonly

SOP(MC)

Perc

ent R

educ

tion

Total Nitrogen

-100

-80

-60

-40

-20

0

20

40

60

80

100

Max SOP+2018

SOP+2017

Vac SOP(HC)

Pilesonly

SOP(MC)

Perc

ent R

educ

tion

Dissolved Nitrogen

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

Not

sta

tistic

ally

sig

nific

ant

95% Significance

90% Significance

85% Significance

80% Significance

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Estimating Phosphorus Load from Leaf Mass on Streets

CategoryAverage Net Weight, lbs.

(80 ft frontage)Lbs. of Leaves Per

Foot of curb

1 5 0.05

2 10 0.13

3 16 0.20

4 25 0.35

1 2 3 4

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Estimating Leachable Phosphorus in Leaves - 2016

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0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

Mea

sure

d TD

P (g

) -Ad

just

ed

Estimated Leaf Mass (g)

Yellowstone

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0 50000 100000 150000 200000 250000

Mea

sure

d TD

P (g

) -Ad

just

ed

Estimated Leaf Mass (g)

Odana

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Ash VS Maple

• On average, Maple leach 18.6 % more TP and 31.3% TDP compare to Ash.

• Before and during 24hr leaching period: Crushed > Intact

• After 48hr leaching period: Crushed < Intact

• At 48hr leachable P amount: TP(intact) > TDP(intact) > TP (crushed) >TDP (crushed)

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Estimate of TDP at Odana

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160

0 50000 100000 150000 200000 250000

Mea

sure

d TD

P (g

) -Ad

just

ed

Estimated Leaf Mass (g)

2016

Proportional 2016

Linear (2016)

Linear (Proportional 2016)

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Estimate of TDP at Yellowstone

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0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

Mea

sure

d TD

P (g

) -Ad

just

ed

Estimated Leaf Mass (g)

2016

2017

Proportional 2016

Proportional 2017

Linear (2016)

Linear (2017)

Linear (Proportional 2016)

Linear (Proportional 2017)

Preliminary Information – Subject to Revision. Not for Citation or Distribution

Next Steps…

• Evaluate the importance of collecting leaf piles – are clean streets more important?

• Evaluate influence of canopy - medium vs. high

• Develop algorithms to predict phosphorus in stormwater• WinSLAMM

Photo Credit: USGS