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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”
•San Lorenzo/Don Castro:•Urbanization
•Lion/Aliso:•Urbanization
•Mining unknown/historicsurfaceunderground
Wildcat/Anza
Lion/Aliso
San Lorenzo/
Don Castro
Our three studywatersheds•Wildcat/Anza:• “Control”
•San Lorenzo/Don Castro:•Urbanization
•Lion/Aliso:•Urbanization
•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)
Dissolved Oxygen (mg/L)
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)
Dissolved Oxygen (mg/L)
WY12
0
1
2
3
4
5
6
0.00 5.00 10.00 15.00
Dep
th (
m)
Dissolved Oxygen (mg/L)
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Dis
so
lve
d O
xyg
en
(m
g/L
)
0
5
10
15
WY16
0
500
1000
1500
2000
2500
3000
WY16
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct 0
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct 0
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Ni (p
pb
)
0
10
20
30
40
50
14 ppm 31 ppm
70 57
Lake Anza Discharge & Metal Flux WY14 & 16
WY16
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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!
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
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)