Nebraska Water Quality Index

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Nebraska. Water Quality. Index. Page 2. A water quality index is… • A single value, from 0 – 100, that represents the chemical health of a river. • A composite ...
Nebraska Water Quality Index

A water quality index is… • A single value, from 0 – 100, that represents the chemical health of a river • A composite value, composed of multiple chemical parameters • A potential tool for public outreach and for estimating project effectiveness

Iowa, as an example WQI to distill thousands of records into meaningful values, and to create a yardstick

• • • • • • • • •

Dissolved oxygen E. coli 5-day BOD Total phosphorus Nitrate + nitrite as N Total detected pesticides pH Total dissolved solids Total suspended solids

Decisions, decisions… 1. 2. 3. 4.

A focus Parameters Criteria A calculation

Focus: nonpoint pollution

Parameters: relevant and regular • • • • • • • •

Temperature Dissolved oxygen pH Total nitrogen Total phosphorus Total suspended solids Atrazine E. coli (fecal coliforms)

Parameters and criteria Parameter Atrazine E. coli pH Temperature

Stream category Source NDEQ Title 117 NDEQ Title 117 NDEQ Title 117 Coldwater NDEQ Title 117 Warmwater NDEQ Title 117 Dissolved oxygen Coldwater A NDEQ Title 117 Coldwater A NDEQ Title 117 Coldwater B NDEQ Title 117 Coldwater B NDEQ Title 117 Warmwater A NDEQ Title 117 Warmwater A NDEQ Title 117 Warmwater B NDEQ Title 117 Warmwater B NDEQ Title 117 Total suspended solids Professional judgment Total nitrogen Moderate land-use model Total phosphorus Moderate land-use model

Dates applicable

Criterion 12 µg/l 126 cells/100 ml 6.5 – 9.0 22°C 32°C October 1 – May 31 4 mg/l June 1 – September 30 8 mg/l July 1 – March 31 4 mg/l April 1 – June 30 5 mg/l October 1 – May 31 3 mg/l June 1 – September 30 5 mg/l October 1 – May 31 3 mg/l June 1 – September 30 5 mg/l 150 mg/l 1518 µg/l 379 µg/l

Nutrients and land use 1518 µg/L

379 µg/L

Criteria are model-predicted estimates at 33% rowcrop in the basin; From Heatherly (2014), Ecological Indicators

Nitrogen sensitivity

*Each line represents a 10% increase or decrease in the TN criterion

Calculation • From the Canadian Council of Ministers of the Environment (CCME 2001) • Also adopted by the UN as a Global Drinking Water Quality Index • Incorporates scope, frequency, and magnitude of criteria exceedance canadarugbyleague.com

WQI  = 100 −

𝐹12 + 𝐹22 + 𝐹32 1.732

# 𝑓𝑎𝑖𝑙𝑒𝑑 𝑝𝑎𝑟𝑎𝑚𝑒𝑡𝑒𝑟𝑠 𝐹1   =   × 100 𝑡𝑜𝑡𝑎𝑙 # 𝑝𝑎𝑟𝑎𝑚𝑒𝑡𝑒𝑟𝑠

# 𝑓𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡𝑠 𝐹2   =   × 100 𝑡𝑜𝑡𝑎𝑙 # 𝑡𝑒𝑠𝑡𝑠

𝑛𝑠𝑒 𝐹3   =   0.01𝑛𝑠𝑒 + 0.01

Scope, the percentage of failed parameters Frequency, the percentage of failed observations Magnitude, how far the failed parameters exceed criteria

𝑓𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛  =   −1 𝑔𝑢𝑖𝑑𝑒𝑙𝑖𝑛𝑒 𝑣𝑎𝑙𝑢𝑒

𝑒𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 𝑛𝑠𝑒  =   𝑡𝑜𝑡𝑎𝑙 # 𝑡𝑒𝑠𝑡𝑠

Long Pine Creek at Long Pine SRA Date

Temp

Atrazine

DO

pH

TN

TP

TSS

E.coli

05/06/2003

14.50

0.03

9.00

8.27

1.71 0.25

13.5

248

05/13/2003

14.54

0.03

10.46

8.09

1.44

0.22

18

36

05/20/2003

12.95

0.11

11.13

7.99

1.68 0.17

9.5

166

05/28/2003

16.70

0.03

9.24

8.27

1.56 0.16

6

291

06/03/2003

13.30

0.03

9.39

8.35

1.54 0.20

7.5

194

06/10/2003

13.70

0.03

8.80

8.17

1.47

0.20

5

488.4

06/17/2003

16.80

0.21

9.70

8.14

1.55 0.17

5

157

06/24/2003

16.64

0.03

7.86

8.07

1.48 0.18

5

345

𝑭𝟏 =

1.71 1.518

WQI  = 100 −

− 1 = 0.125, etc.

× 𝟏𝟎𝟎 = 25.00

𝟏𝟑 𝑭𝟐 = × 𝟏𝟎𝟎 = 𝟐𝟑. 𝟐𝟏 𝟓𝟔 𝑭𝟑   =  

𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛  =  

𝟐 𝟖

𝑛𝑠𝑒  =  

28.572 :23.212 :2.24 2 1.732

𝟎.𝟎𝟐𝟑 𝟎.𝟎𝟏(𝟎.𝟎𝟐𝟑):𝟎.𝟎𝟏 1.292 56

= 2.24

= 0.023

= 78.71 = GOOD

Assigning quality Class Excellent

WQI scores 90-100

Good

70-89.99

Fair

50-69.99

Poor

1-49.99

Long Pine Creek at Long Pine SRA Date

Temp

Atrazine

DO

pH

TN

TP

TSS

E.coli

05/06/2003

14.50

0.03

9.00

8.27

1.71

0.25

13.5

248

05/13/2003

14.54

0.03

10.46

8.09

1.44

0.22

18

36

05/20/2003

12.95

0.11

11.13

7.99

1.68

0.17

9.5

166

05/28/2003

16.70

0.03

9.24

8.27

1.56

0.16

6

291

06/03/2003

13.30

0.03

9.39

8.35

1.54

0.20

7.5

194

06/10/2003

13.70

0.03

8.80

8.17

1.47

0.20

5

488.4

06/17/2003

16.80

0.21

9.70

8.14

1.55

0.17

5

157

06/24/2003

16.64

0.03

7.86

8.07

1.48

0.18

5

345

• Advantages – Any time interval – Missing values OK

• Disadvantage – Skewed by missing parameters

Ambient Network Water Quality 2014

Nonpoint & point sources

Agricultural draining river

Industrial effluent draining river

Water quality among basins

Trends in the ambient network

Significant temporal trends

Antelope Creek at State Fair Park

F1

• WQI increasing mostly from the F1 & F3 components • TP and TSS exceeded less often

F3

• Magnitude of exceedances decreased

Antelope Creek at State Fair Park

TN no longer peaks above 10 mg/L

Pine Creek S. of Rushville

F1

• WQI decreasing mostly from the F1 component • TSS exceeded 150 mg/L more frequently • E. coli collected 2014

Shell Creek NE of Columbus

Shell Creek is impaired for Atrazine

Shell Creek NE of Columbus

Still impaired for Atrazine, but the creek has been improving in water quality

Lincoln

Grand Island

North Platte

Ogallala

Sidney

R2 = 0.539, P < 0.001

R2 = 0.429, P < 0.001

WQI shows importance of the effluent for the receiving systems, may be a target for improvement

35.98, POOR 17.91, POOR 34.61, POOR

60.48, FAIR

71.88, GOOD

36.56, POOR

Recap • Outreach tool • Analysis of trends • Point & nonpoint remediation • Possible quality target • Demonstration of success

Questions?