Water Quality Monitoring on Larkin Creek

St. Francis County, AR

JL Bouldin

RA Warby

Arkansas State University

Background

• Larkin Creek is a tributary of the L’Anguille River – dominated by row crop agriculture.

• L’Anguille River is a tributary of the St. Francis River in eastern Arkansas in the Delta ecoregion

• ADEQ authorized the St. Francis County Conservation District to implement BMPs to reduce pollutant loading to L’Anguille

Site description

Lateral 1-A of Larkin Creek– Tributary of the

L’Anguille River– HUC#080202050506

St. Francis County

Site description

St. Francis County

Site description

Lateral 1-A of Larkin Creek– Tributary of the

L’Anguille River– HUC#080202050506

BMPs

St. Francis County Conservation District • sediment pond construction• plant riparian buffers• remove sediment• restore the channel

– Lateral 1-A of Larkin CreekL’Anguille River• Agricultural activities cited as major cause of the

impairment within watershed– excessive turbidity from silt, suspended solids

loading, sedimentation

Objectives

• Determine baseline data prior to BMP implementation

• Weekly grab samples• Total Suspended Solids• pH• Dissolved Oxygen• Nutrients

– Nitrate, Nitrite, Orthophosphate

Upper Larkin Creek site

Upstream Downstream

TSS

0

5

10

15

20

25

30

35

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

mg/

L

pH

6.70

6.80

6.90

7.00

7.10

7.20

7.30

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

DO

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

mg/

L

Middle Larkin Creek site

Upstream Downstream

TSS

0

100

200

300

400

500

600m

g/L

pH

6.606.807.007.207.407.607.808.008.208.40

DO

0.0

5.0

10.0

15.0

20.0

25.0

mg/

L

Lower Larkin Creek site

Upstream Downstream

TSS

0

2

4

6

8

10

12

14

mg/

L

pH

0.001.002.003.004.005.006.007.008.009.00

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

DO

0.02.04.06.08.0

10.012.014.016.018.0

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

mg/

L

TSS at all sites

Larkin Creek TSS

0255075

100125150175200225250275300325350375400425450475500525

6/9/10

6/16/10

6/23/10

6/30/10

7/7/10

7/14/10

7/21/10

7/28/10

8/4/10

8/11/10

8/18/10

8/25/10

9/1/10

9/8/10

9/15/10

TSS

(mg/

L)

Upper

Middle

Lower

Preliminary results

• TSS highest at Middle Site– Especially following rain events– Will benefit from upstream sedimentation pond

• pH lowest at Upper and Middle sites from temporary acidification following rain events

• DO high due to increased primary production and early afternoon sampling times

• Final sampling and nutrient data pending

Questions?

Upper Larkin Creek Lower Larkin CreekMiddle Larkin Creek