Lake Restoration in the UK: lessons fromthe CEH case studies

Linda May, Bryan Spears, Sebastian Meis, Bernard Dudley, StephenMaberly, Laurence Carvalho, Iain Gunn, Dave Carss, and Ian Winfield

www.ceh.ac.uk

• Why is lake restoration important?

• Improving our understanding ofrestoration and recovery processes

• Providing the evidence base to supportdecision makers

Regulation

Climate

Why is lake restoration important?

Direct impacts: degradation of water quality

Good water quality Bad water quality

Pollution

Indirect impacts: loss of wildlife habitat & amenity value

POCHARD BROWN TROUT

GREAT CRESTED NEWT OTTERS

Impacts of pollution on lake water quality

Good water quality Bad water quality

Recovery?

Degradation

Recovery is not the reverse ofdegradation!

CEH’s aim

To provide the scientific evidencethat helps lake managers to:• Identify water quality problems

• Diagnose the causes (correctly!)

• Set restoration targets

• Manage the recovery process

Based on a series of case studies.

Evidence based managementdecisions are the key to success

CASE STUDY 1: Loch Leven (natural recovery)

Cost of ‘Scum Saturday’ (1992): £1M

CEH data: 1968-1985

May & Spears (2012) Loch Leven: 40 years of scientific research. Dev. in Hydrobiology. (10 papers).

May & Spears (2012) Loch Leven: 40 years of scientific research. Developments in Hydrobiology. (10 papers).

CASE STUDY 1: Loch Leven (natural recovery)

• Catchment P sources reduced by60%

• Chemical recovery took > 15years

• Slow recovery driven by releaseof legacy P from sediment stores

Target

Cost of ‘scum Saturday’: £1MWat

er c

olum

n TP

con

c. (µ

g l-1

)

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 20090

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P input 60%

Recovery delayed by internal recycling of legacy P

P input reduced by 60%

Recovery delayed by internal recycling of legacy P

0

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68-7

373

-78

78-8

383

-88

88-9

393

-98

98-0

303

-08

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1000PochardPochard Scotland

CASE STUDY 1 : Loch Leven (natural recovery)

0

10

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30

2008 2009 2010 2011 2012

Larg

e fis

h (in

divi

dual

s ha

-1)

Year

Large fish(ind. ha-1)

Annual P input to lake (tonnes)

Macrophytegrowing depth

(m)

Loch LevenScotland

x

• Long history of eutrophication• P inputs from WWTW, agriculture &

pig farm• Cyanobacterial blooms in summer• Natural recovery unlikely; no surface

outflow

CASE STUDY 2: Loch Flemington (managed recovery)

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tota

l pho

spho

rus

(µg

L-1)

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300SEPA pre-application data (average 2000-2003)CEH pre-application data (May 2009 - March 2010)

CASE STUDY 2: Loch Flemington (managed recovery)

Average P concentrationBefore application 74 µg P l-1After application 37 µg P l-1WFD target 32 µg P l-1

• Phoslock® controlled release of legacy Pfrom lake sediments

• Potential to speed up chemical recoveryfrom eutrophication demonstrated

• Ecological recovery still being monitored

• Other P binding products underdevelopment, e.g. from waste products+ 25 t of Phoslock®, March 2010

Meis (in prep) Investigating forced recovery from eutrophication in shallow lakes. PhD thesis, Univ. Cardiff. Submission 2012.

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tota

l pho

spho

rus

(µg

L-1)

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300SEPA pre-application data (average 2000-2003)CEH pre-application data (May 2009 - March 2010)CEH post-application data (March 2010 - February 2011)

Norton et al. (2011). Using models to bridge the gap between land use and algal blooms: an example from the Loweswater catchment, UK. Environmental Modelling and Software.

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Annu

al m

ean

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ylla

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m-3

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Phosphorus load (kg SRP y-1)

H:G

G:M

M:P

S3S2

S3A

S2A

S1

S1AS5

S4

S5A S4A

Good/Moderate WQ status

High/Good WQ status

Moderate/Poor WQstatus

CASE STUDY 3: Loweswater (stakeholder involvement)

Aim: to “de-water”, extract coal, solve pollutionproblems and rebuild to meet water qualitytargets

But: causes of problem need to be properlyidentified and advice needs to be based onsound scientific evidence

May et al. (2011). An assessment of recovery targets, endpoints and timelines associated with the proposed restoration of Loch Fitty (Fife). Report to Scottish Coal Company Limited (SCCL). 81pp.

CASE STUDY 4: Loch Fitty (extreme restoration)

CASE STUDY 5: Kinghorn Loch (multiple pollutants)

• Polluted by red mud from an aluminium works 1950s to1983; recovery since 1984

• Symptoms: algal blooms, fish kills, less macrophytes andmacroinvertebrates

• 30 years of data enables recovery from multiple pressuresto be investigated

• Initial results suggest that chemical recovery is slow(decades) and pollutant specific

• Ecological response still being investigated

V (ug/l)

80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10

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Vanadium(µg l-1)

PO4-P (mg/l)

80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10

0.0

0.1

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PO4-P(mg l-1)

As (ug/l)

80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10

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Arsenic(µg l-1)

Kinghorn LochUsers Group

Accumulating knowledge from multiple case studies …

… helps inform future decision making

Linlithgow Loch(Linlithgow Council/Historic Scotland)

Llangorse Lake(CCW)

Loch Leven(NERC/SNH/SEPA/EU)

Loweswater(NERC Relu)

Loch Flemington(NERC/Phoslock®)

Hornsea Mere(NE)

Clatto Reservoir(Phoslock®/NERC/Dundee City Council

Bassenthwaite(EA)

Shropshire/Cheshire meres(NE; EA)

Loch Fitty(SEPA/Scottish Coal)

Kinghorn Loch(Fife Council/SEPA/NERC)

Haining Loch(Tweed Forum)

Moor Loch

Rescobie & Balgavies Lochs(Hutton/SEPA/SAC)

Coldingham Loch(Owner)

Alderfen Broad(EA)

Rouken Glen Pond(East Renf. Council)

Esthwaite(EA; EU; NERC)

Is there an outflow and asource of TP replete

water?Is product flush-out likely?

Is the loch very shallow?

Are monthly monitoring data available?

Is there evidence of internal P loading?

Is there evidence of external P loading?

Y

Y

N

Both

Reduce external P load

Site specific study required

Continue monitoringIs algal N-limitation apparent?

Are protected speciespresent?

Y

N

Does the site fail WFD for TP and Chl? NoTP

Y

Consider N control

N

Investigate trophicinteractions

Is algal P-limitation apparent?N

Y

N N

N

Consider P capping

Y Y Consider flushing

N Consider dredging

Y

Allow naturalrecovery

Spears et al., Report to the Environment Agency (2011)

Delivering decision support tools for water managers

Information available via the CEH website

http://www.ceh.ac.uk/sci_programmes/UK-Lakes-Restoration.html

Thank you for your attention!