Investigating the Linkage between Water

Quality and Water Quantity in

Watershed Management

Richard L. Kiesling 1United States Geological Survey, Water Resource Division, Texas District, 8027 Exchange Drive, Austin, TX, 78754

2Environmental Science Institute, University of Texas, Austin, TX, 78712

Why Evaluate Impact of Streamflow?

• Streamflow acts as a master variable• Controls Water Residence Time• Regulates Rates of Physical Disturbance • Regulates Nutrient and Carbon Cycling

– nutrient uptake length a function of stream depth and velocity (e.g., Valett et al. 1996)

– nutrient assimilation and turnover rates a function of discharge (Butterini and Sabater 1998).

• Regulates Channel Characteristics– Hydro-geomorphology

Water Resource Functions

• Aesthetics – enhancement of property values• Habitat – fish and wildlife survival and

reproduction• Hydro-electric power generation• Recreation – swimming, boating, fishing• Seafood production – freshwater inflows for

shellfish and finfish production• Water quality – assimilation of waste and

production of safe drinking water• Water supply – Ag, Domestic, Industrial,

Recreation

Investigating the Linkage

• Approach –– Technical evaluation of the impact of instream

flows on wastewater effluent assimilation

• Methodology –– Run calibrated QUAL-TX water quality model

with alternative instream flow criteria– Compare model output for alternative effluent

sets under different static flow conditions

Acknowledgments

• TCEQ• Joan Flowers, Carter and Burgess

• TIAER• US EPA

• Tarleton State University• Amy Findley

• Jeff Back

Water Quality Simulations: Rio Grande

• Calibrated QUAL-TX Model

• Modified Headwater Flow– 60% and 40% of median daily flow from Fort Quitman

Gage 1923 through 1950 (3.6 m3/sec and 2.4m3/sec)

• Conserved Pollutant Load

• Modeled Alternative Load Scenarios– Increased BOD load by 20mg/L for two flow scenarios

• Compared Predicted Instream [DO]

Rio Grande / Rio Bravo Basin

Concentration Load (Kg/day) Concentration Load (Kg/day) Concentration Load (Kg/day)Flow (m3/s) 0.25 - 3.60 - 2.40 -Temperature (C) 17.80 - 17.80 - 17.80 -Salinity (ppt) 0.50 - 0.50 - 0.50 -Conductivity (umhos/cm) 831 - 830.79 - 830.79 -Chloride (mg/L) 85.27 - 85.27 - 85.27 -DO (mg/L) 7.05 - 7.05 - 7.05 -BOD (mg/L) 4.36 92.32 0.30 92.32 0.45 92.32Org-N (mg/L) 1.93 40.94 0.13 40.94 0.20 40.94NH3 (mg/L) 3.68 77.86 0.25 77.86 0.38 77.86NO3+2 (mg/L) 2.00 42.25 0.14 42.25 0.20 42.25* Computed f rom Fort Quitman Gage

Headw ater inputs f rom Upper Rio GrandeOriginal Flow f rom WLE 60% of Median Flow * 40% of Median Flow *

Rio Grande: Alternative Load Scenarios

QUAL-TX Predicted Dissolved Oxygen ConcentrationsSegment 2308: Rio Grande Be low International Dam

4

5

6

7

8

012345678910111213141516171819202122232425262728

Original QUAL-TX WLE 7Q2 flow (0.245 m3/s, BOD=20mg/L))

60% of Fort Quitman Median Flow (3.6 m3/s, BOD=20 mg/L)

40% of Fort Quitman Median Flow (2.4 m3/s, BOD=20 mg/L)

Rio Grande: Alternative Load Scenarios

QUAL-TX Predicted Dissolved Oxygen ConcentrationsSegment 2308: Rio Grande Below International Dam

4

5

6

7

8

012345678910111213141516171819202122232425262728

60% of Fort Quitman Median Flow (3.6 m3/s, BOD=20 mg/L)40% of Fort Quitman Median Flow (2.4 m3/s, BOD=20 mg/L)Additional BOD Load Scenario 1 (Flow=3.6 m3/s, BOD=40)Additional BOD Load Scenario 2 (Flow=2.4 m3/s, BOD=40)

Rio Grande: Alternative Load Scenarios

Water Quality Simulations: North Bosque

• Used Calibrated TNRCC QUAL-TX Model

• Modified Headwater Flow– Default Instream Flow restriction based on 60% or 40%

of median daily flow recorded at Clifton Gage

• Conserved Pollutant Load

• Modeled Alternative Load Scenarios– Increased BOD load by 20mg/L for two flow scenarios

• Compared Predicted Instream [DO]

TIAER Graphic; used by permission

BO070

BO090

NC060

BO060

BO040

 

Simulation Number

Headwater flow (cfs)

Clifton BOD (mg/L)

Clifton NH3-N (mg/L)

Valley Mills BOD (mg/L)

Valley Mills NH3-N (mg/L)

TCEQ/ TNRCC

0.002 10 12 10 12

1 4.9 10 12 10 12

2 1.0 10 12 10 12

3 0.6 10 12 10 12

4 4.9 20 15 10 12

5 4.9 10 12 20 15

6 0.6 20 15 10 12

7 0.6 10 12 20 15

8 0.002 20 15 10 12

9 0.002 10 12 20 15

North Bosque: Alternative Load Scenarios

QUAL-TX Simulations of North Bosque River

4

5

6

7

8

0 20 40 60 80 100

River Kilometers upstream of Lake Waco

DO

Con

cent

rati

on (

mg/

L)

Original 1226_1 1226_4 1226_8

Valley Mills WWTP

Clifton WWTP

Meridian WWTPOriginal = 0.002 cfs; 10 mg/L BOD

1226_1 = 4.9 cfs; 10 mg/L BOD

1226_4 = 4.9 cfs; 20 mg/L BOD

1226_8 = 0.002 cfs; 20 mg/L BOD

Downstream Upstream

QUAL-TX Simulations of North Bosque River

4

5

6

7

8

40 50 60 70

River Kilometers upstream of Lake Waco

DO

Con

cent

rati

on (

mg/

L)

Original 1226_1 1226_4 1226_8

Valley Mills WWTP

Clifton WWTP

Original = 0.002 cfs; 10 mg/L BOD

1226_1 = 4.9 cfs; 10 mg/L BOD

1226_4 = 4.9 cfs; 20 mg/L BOD

1226_8 = 0.002 cfs; 20 mg/L BOD

Simulation Study Conclusions

• Maintenance of instream flows above critical low flows increased modeled assimilative capacity

• Potential exists for economic trade-off between wastewater treatment costs and instream flow to maintain assimilative capacity

• Integrated water resource management requires the simultaneous assessment of streamflow manipulation and assimilative capacity– Does this apply to all constiuents?

System Model of Nutrients and Watershed Eutrophication

• Nutrient supply can limit algal production• Nutrient enrichment from watershed and marine

sources can control extent of limitation• Control Points within watersheds dictate trophic-

level responses to nutrient enrichment; for example– Frequency and magnitude of loads– Spatial and temporal change in LULC– Hydro modification (entrenchment, diking)

In-stream Methods: algal production

• NDS periphytometers apparatus design –– Liquid media diffusing through two-layer substrate

• 0.45 micron nylon barrier filter• GFF substrate - analyzed for algal biomass or carbon

• Factorial Experiments – factors, 1 level each, interaction term– Six Sites in North Bosque River Watershed– Nutrient media additions of 350 uM N and 100 uM P– Eight replicates per treatments– 10-14 day deployments; micro and macro methods

TIAER Graphic; used by permission

BO070

BO090

NC060

BO060

BO040

Matlock Periphytometer, North Bosque River, Hico TX

Micro-NDS Periphytometer, North Bosque River, Hico TX

North Bosque Control Periphyton Productivity

0

100

200

300

400

500

Site

Pro

du

ctiv

ity

(μg

Ch

la/m

2 /day

)

0

10

20

30

40

50

Pro

du

ctiv

ity

(mg

DW

/m2/d

ay)

May 2001 Aug 2001 Oct 2001 Jan 2002 Apr 2002

USGS 08095000 North Bosque nr Clifton

0

500

1000

1500

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

Month

Mo

nth

ly-M

ea

n D

isc

ha

rge

(c

fs)

2000

2001

2002

North Bosque Ambient Chemistry 2001-2002

0

0.5

1

1.5

2

2.5

BO020 BO040 BO060 BO070 BO090 NC060

Ph

osp

ho

rus

(mg

/L)

0

50

100

150

200

250

Per

iph

yto

n P

rod

uct

ion

(μg

Ch

la /m

2/d

ay)

Average of PO4-P (mg/L) Average of TP (mg/L)

Periphyton Production

Bosque River, TX, P-Limited Production

0.0

0.4

0.8

1.2

0.0 0.4 0.8 1.2 1.6 2.0

Instream SRP (mg/L)

Ind

ex

of

Re

lati

ve

Pro

du

cti

on

(L

ET

SI)

1997-98 2001-2002 Monod Model

Monod Model:umax =0.98; Ks =0.01

R2 = 0.73; p < 0.05

North Bosque Monthly-Mean NPP: 2001-2002

0

1

1

2

2

May June July August

Month

Net

Pri

mar

y P

rod

uct

ion

(m

g O

2/L

/hr)

BO040

BO060

BO070

BO090

USGS 08095000 North Bosque nr Clifton:Monthly-Mean Discharge

0

50

100

150

200

May June July August

Month

Dis

char

ge (c

fs)

2001 Q

2001-2002 Mean Q

2001-2003 Mean Q

Conclusions: Watershed Eutrophication

• Nutrient-limited periphyton primary production conforms to resource-consumer model of population growth based on resource supply rate

• Periphyton primary productivity is elevated along the instream nutrient concentration gradient, documenting a change in trophic status

• Periphyton and water-column primary productivity at Clifton (BO090) track mean discharge as well as nutrient concentration

Micro-NDS PeriphytometerTaos Ski Valley, New Mexico

Micro-NDS Periphytometer

Steer Creek, Oregon

Dr. Richard KieslingUS Geological Survey8027 Exchange DriveAustin, TX 78754

kiesling@usgs.gov(512) 927-3505

Contact Information

Dr. Richard KieslingUS Geological Survey8027 Exchange Drive

Austin, TX 78754

kiesling@usgs.gov(512) 927-3505

Buffalo Bayou Example

• Proposed to augment flow of Buffalo Bayou from upstream flood control reservoir

• Maximum annual demand for instream flow releases was 62,985 ac-ft per year

• WWTP alternative cost $22.1 million for construction and operation (2001 dollars)

• Alternatives approximately equivalent at raw water cost of $350 per ac-ft (2001 dollars)

Economic Evaluation Observations

• Example illustrates the potential for benefits analysis associated with the maintenance of instream flows

• Example demonstrates the potential value of integrated functional analysis of water quality and water quantity

• Raises questions regarding costs estimates available for this type of planning exercise

Water Quality Simulations: Rio Grande

• Calibrated QUAL-TX Model

• Modified Headwater Flow– 60% and 40% of median daily flow from Fort Quitman

Gage 1923 through 1950 (3.6 m3/sec and 2.4m3/sec)

• Conserved Pollutant Load

• Modeled Alternative Load Scenarios– Increased BOD load by 20mg/L for two flow scenarios

• Compared Predicted Instream [DO]