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Management Implications for Small Urban Reservoirs Based on a Multi-Year Study of Three Alameda County Watershed-Reservoir Pairs

Kristina Faul (Mills College) and Laura Rademacher (University of the Pacific)Celine Barrera and Maria-Elena Ramos (Mills College)

Motivation: Small urban watersheds are important but understudied

Motivation:Ideal for undergraduate research!

Goals of our study:To determine….(1) whether small, urban reservoirs serve as sources (or sinks) for carbon, nutrients, and metals to the Bay

Reservoir

Goals of our study:To determine….(2) whether perennial reservoirs are more efficient sinks for carbon, nutrients, and metals than ephemeral reservoirs;

Perennial reservoir—always full

vs

Ephemeral reservoir—full/empty seasonally

Goals of our study:To determine….(3) the recent history of environmental impacts on East Bay watersheds from sediment records from small, urban reservoirs.

Our three studyEast Bay watersheds Wildcat/Anza

Lion/Aliso

San Lorenzo/

Don Castro

•Wildcat/Anza:• “Control”

•San Lorenzo/Don Castro:•Urbanization

•Lion/Aliso:•Urbanization

•Mining

Our three studywatersheds•Wildcat/Anza:• “Control”



•Mining unknown/historicsurfaceunderground

Wildcat/Anza

Lion/Aliso

San Lorenzo/

Don Castro

Our three studywatersheds•Wildcat/Anza:• “Control”



•Miningunknown/historicsurfaceunderground

Wildcat/Anza

Lion/Aliso

San Lorenzo/

Don Castro

Lake Anza/Dammed Wildcat CreekCurrent uses are recreation, swimming, fishing (not stocked)Dam built in 1938 for recreational purposes

Wildcat Creek Watershed & Lake Anza• Watershed 4.0

km2

• Lake surface area 40,000 m2

• Average depth 1 to 2 m

• Perennial

Mostly EB Regional parkland

Continually full

Don Castro Reservoir/Dammed San Lorenzo CreekCurrent uses: recreation, fishing (stocked)Dam built in 1964 for flood control

San Lorenzo Creek Watershed & Don Castro Reservoir• Watershed 51 km2

• Surface Area 87,000 m2

• Average depth 1 m

• Perennial

Don Castro / San Lorenzo

Freeways

Industrial

Continually full

Lake Aliso/Dammed Lion CreekCurrent uses: campus irrigation, flood control

Full in summer/empty in winter

Summer

Winter

Lion Creek Watershed & Lake AlisoWatershed = 4.4 m3

Surface Area = 7,400 m2

Percent Current Volume of Capacity= 50%

Downstream of a former sulfur mine

Managed by Mills College: ephemeral

Mining impacts

Freeways

Intermittent filling

Leona Heights Sulfur Mine:See Laura Rademacher’s Poster!

Oxidation of Sulfur in Pyrite to Sulfate:◦ 2 FeS2 (s) + 7 O2 + 2 H2O → 2 Fe+2 + 4 SO4

-2 + 4 H+

Oxidation of Fe+2 to Fe+3:◦ 4 Fe+2 + O2 +4 H+

→ 4 Fe+3 + H2O

Precipitation of iron hydroxide:◦ Fe+3 + 3 H2O → Fe(OH)3 + 3H+

Mine Site

Lake Aliso

Field Methods:In situ data collection•Bimonthly at inlet, outlet, reservoir:•Temperature

•Dissolved Oxygen

•Conductivity

•pH

•Alkalinity

•Total Dissolved Solids

Field Methods:Water Discharge at Inlet & Outlet

Width (m)

Depth (m)

Velocity (m/s)

Discharge = W * D * Velocity

= m3/s

Field Methods:Water Sample Collection•Bimonthly at inlet, outlet, in reservoir:•Cations

•Anions

•Trace metals

•Total Inorganic Carbon/Total Organic Carbon

Lab Methods: ICP-MS for Trace MetalsFe, Mn, Ni, As, Pb, Cu, Zn

In Situ Data & Water Samples CollectedWater-shed

2010 2011 2012 2013 2014 2015 2016 2017 2018

Anza/Wildcat

✓ ✓ ✓ ✓

Don Castro/San Lorenzo

✓ ✓ ✓ ✓

Aliso/Lion

✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

California Drought 2012-2016

Results: Lake Anza Depth Profiles WY14 & WY16

0

0.5

1

1.5

2

2.5

3

3.5

4

0 10 20 30

Dep

th (

m)

Temperature (°C)

WY16

12/5/15

1/31/16

2/13/16

4/2/16

4/9/16

4/23/16

5/1/16

6/15/16

7/1/16

7/28/16

0

0.5

1

1.5

2

2.5

3

3.5

4

0 10 20 30

Dep

th (

m)

Temperature (°C)

WY 14

10/6/13

10/27/13

11/3/13

11/17/13

12/1/13

2/2/14

2/16/14

3/2/14

3/16/14

3/30/14

4/13/14

4/27/14

6/11/14

6/23/14

7/7/14

7/21/14

8/4/14

9/7/14

9/21/14

0

0.5

1

1.5

2

2.5

3

3.5

4

0 5 10 15

Dep

th (

m)

DIssolved Oxgyen (mg/L)

WY16

0

0.5

1

1.5

2

2.5

3

3.5

4

0 5 10 15

Dep

th (

m)

Dissolved Oxygen (mg/L)

WY14

Results: Don Castro Depth Profiles WY14 & 16

0.0

0.5

1.0

1.5

2.0

0 10 20 30

Dep

th (

m)

Temperature (°C)

WY16

10/10/2015

10/24/2015

11/7/2015

11/21/2015

12/11/2015

2/6/2016

2/20/2016

3/12/2016

4/3/2016

4/16/2016

4/30/2016

6/16/2016

6/30/2016

7/14/2016

7/29/2016

8/9/2016

0.0

0.5

1.0

1.5

2.0

0 5 10 15

Dep

th (

m)


WY14

0.0

0.5

1.0

1.5

2.0

0 5 10 15

Dep

th (

m)

Dissolved Oxygen (°C)

WY16

0.0

0.5

1.0

1.5

2.0

0 10 20 30

Dep

th (

m)

Temperature (°C)

WY14

10/5/2013

10/19/2013

11/2/2013

11/16/2013

11/24/2013

12/15/2013

2/1/2014

2/15/2014

3/1/2014

3/15/2014

4/12/2014

4/26/2014

6/13/2014

6/24/2014

7/8/2014

7/22/2014

8/5/2014

9/6/2014

Results: Lake Aliso Depth Profiles WY14 & 16

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 10 20 30

Dep

th (

m)

Temperature (°C)

WY12

10/1/201110/16/201111/5/20112/25/20123/10/20124/7/2012

5/30/20126/6/2012

6/14/20126/23/20126/29/20127/5/2012

7/12/20127/15/20127/26/20128/4/2012

8/7/2012

8/31/2012

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0.00 10.00 20.00 30.00

Dep

th (

m)

Temperature (°C)

WY16

10/11/2015

10/25/2015

11/6/2015

11/22/2015

12/13/2015

3/22/2016

4/2/2016

4/17/2016

6/17/2016

6/29/2016

7/12/2016

7/27/2016

8/6/2016

8/27/2016

9/11/2016

9/25/2016

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0.00 5.00 10.00 15.00

Dep

th (

m)


WY12

0

1

2

3

4

5

6

0.00 5.00 10.00 15.00

Dep

th (

m)


WY16

WY14

Sp

ec C

on

du

cta

nce (

mic

roS

/cm

)

0

200

400

600

800

1000

Inlet

Outlet

WY16

0

200

400

600

800

1000

WY14

WY14

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

Dis

so

lved

Oxyg

en

(m

g/L

)

0

5

10

15

20

WY16

WY 16

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct 0

5

10

15

20

Results: Lake Anza Inlet/Outlet WY 14 & 16

Results: Don Castro Inlet & Outlet WY14 & 16WY14

Sp

ec C

on

du

cta

nc

e (

mic

roS

/cm

)

0

500

1000

1500

2000

2500

3000

Inlet

Outlet

WY14


Dis

so

lve

d O

xyg

en

(m

g/L

)

0

5

10

15

WY16

0

500

1000

1500

2000

2500

3000

WY16


5

10

15

Results: Aliso Inlet & Outlet WY12 &16WY12

Sp

ec C

on

du

cta

nc

e (

mic

roS

/cm

)

0

1000

2000

3000

4000

5000

6000

7000

Inlet

Outlet

WY12


Dis

so

lve

d O

xyg

en

(m

g/L

)

0

3

6

9

12

15

WY16

0

1000

2000

3000

4000

5000

6000

7000

WY16


3

6

9

12

15

Results: Lake Anza/Wildcat Metals WY14 & 16WY14

Fe (

pp

b)

0

50

100

150

200

250

300

Surface

Bottom

Inlet

Outlet

WY14

Ni (p

pb

)

0

2

4

6

8

10

WY16


Ni (p

pb

)

0

2

4

6

8

10

WY16

Fe (

pp

b)

0

50

100

150

200

250

300830 ppb

WY14

Fe (

pp

b)

0

100

200

300

400

Surface

Inlet

Outlet

WY14

Ni

(pp

b)

0

5

10

15

WY16

Fe (

pp

b)

0

100

200

300

400

WY16


Ni

(pp

b)

0

5

10

15

Results: Don Castro/San Lorenzo Metals WY14 & 16

SamplingGap

Due toHighFlow

Results: Lake Aliso/Lion Creek Metals WY12 & 16WY12

Fe (

pp

b)

0

200

400

600

800

1000

WY12

Ni (p

pb

)

0

10

20

30

40

50

WY16 - Note scale is 5x higher than WY12!

Fe (

pp

b)

0

1000

2000

3000

4000

5000

Surface

Bottom

Inlet

Outlet

WY16


Ni (p

pb

)

0

10

20

30

40

50

14 ppm 31 ppm

70 57

Lake Anza Discharge & Metal Flux WY14 & 16

WY16


Fe F

lux (

g/d

ay)

0

200

400

600

800

Ni F

lux (

g/d

ay)

0

5

10

15

20

WY16

Dis

ch

arg

e (

L/d

ay)

0.0

2.0e+6

4.0e+6

6.0e+6

8.0e+6

1.0e+7

1.2e+7

WY14

Dis

ch

arg

e (

L/d

ay)

0.0

2.0e+6

4.0e+6

6.0e+6

8.0e+6

1.0e+7

1.2e+7

Inlet

Outlet

WY14

Fe F

lux (

g/d

ay)

0

200

400

600

800

Ni F

lux (

g/d

ay)

0

5

10

15

20

Inlet Fe

Outlet Fe

Inlet Ni

Outlet Ni

Don Castro Discharge and Metal Flux: WY14 & 16WY14

Dis

ch

arg

e (

L/d

ay)

0

5e+6

1e+7

2e+7

2e+7

3e+7

3e+7

WY16

Dis

ch

arg

e (

L/d

ay)

0

5e+6

1e+7

2e+7

2e+7

3e+7

3e+7

WY16


Fe F

lux

(g

/da

y)

0

200

400

600

800

1000

Ni

Flu

x (

g/d

ay)

0

20

40

60

80

100

WY14

Fe F

lux

(g

/da

y)

0

200

400

600

800

1000

Ni

Flu

x (

g/d

ay)

0

20

40

60

80

100

Inlet Fe

Outlet Fe

Inlet Ni

Outlet Ni

Results: Aliso Discharge and Metal Flux WY12 &16WY12

Dis

ch

arg

e (

L/d

ay)

0.0

5.0e+6

1.0e+7

1.5e+7

2.0e+7

2.5e+7

Inlet

Outlet

WY12

Fe F

lux (

g/d

ay)

0

100

200

300

400

500

Ni F

lux (

g/d

ay)

0

50

100

150

200

Inlet Fe

Outlet Fe

Inlet Ni

Outlet Ni

WY16

Dis

ch

arg

e (

L/d

ay)

0.0

5.0e+6

1.0e+7

1.5e+7

2.0e+7

2.5e+7

WY16-Scale is 10x the WY12 Fe scale!


Fe F

lux (

g/d

ay)

0

1000

2000

3000

4000

5000

Ni F

lux (

g/d

ay)

0

50

100

150

20013,000

Results:Lake Anza Sediment Cores

Results:Don Castro Sediment Cores

Results:LakeAlisoSedimentCores

Conclusions:Summary of Findings So Far…Reservoir Management Style Stratification/

Dissolved OxygenSource or Sink? Sediment Metal

Content

Anza Perennial Seasonallysomewhatstratified/Higher DO

Fe & Ni Source in WY14 (drought)Fe & Ni Sink in WY16 (end drought)

Relatively low/consistent

Don Castro Perennial Not stratified/Lower DO

Fe & Ni Source in WY14 & WY16

Increasing towards present

Aliso Ephemeral Seasonally wellstratified/Lower DO

Fe Source in WY14 (drought)Fe & Ni Sink in WY16 (end drought)

Relatively high/variable

What might account for the difference in metal behavior between Anza and Aliso?ANZA ALISO

AcknowledgmentsUndergraduate Students

At Pacific: G. Alldredge, K. Gomez, D. Schilling, R. Ward, J. Yun,

B. Klemm, N. Mainwaring

At Mills: S. Bhatnagar, Z. Dell, A. Fiorini, A. Fowler, G. Gebhardt,

H. Glicker, R. Jensen, L. Kong, S. Kreutzer, R. Sandoval, N.

Labarca, C. Le, N. Lemon, P. Miranda, M. Murphy, J. Moore, M.

Nutt, M. Page, A. Parmidge, E. Rigby, J. Rodriguez, A. Savage, A.

Scholtz, K. Singh, C. Soares, R. Stewart-Laws, C. Stitt, O. Sun, L.

Tice, A. Timm, C. Wu, L. Zentner

Funding: USC Sea Grant, Pacific Fund, Mills College

Other Support: East Bay Regional Parks; K. Burmeister (GIS)

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