1. Nebraska Water Quality Index

2. 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

3. Iowa, as an example
Dissolved oxygen
E. coli
5-day BOD
Total phosphorus
Nitrate + nitrite as N
Total detected pesticides pH
Total dissolved solids
Total suspended solids
WQI to distill thousands of records into meaningful values, and to create a yardstick

4. Iowa as a (less good) example

5. Decisions, decisions…
A focus
Parameters
Criteria
A calculation

6. Focus

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

8. Parameters and criteria
Stream category
Source
Dates applicable
Criterion
Atrazine
NDEQ Title 117
12 µg/l
E. coli
126 cells/100 ml pH
6.5 – 9.0
Temperature
Coldwater
22°C
Warmwater
32°C
Dissolved oxygen
Coldwater A
October 1 – May 31
4 mg/l
June 1 – September 30
8 mg/l
Coldwater B
July 1 – March 31
April 1 – June 30
5 mg/l
Warmwater A
3 mg/l
Warmwater B
Total suspended solids
Professional judgment
150 mg/l
Total nitrogen
Moderate land-use model
1518 µg/l
Total phosphorus
379 µg/l

9. Nutrients and land use
1518 µg/L
379 µg/L

10. Nitrogen sensitivity

11. 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

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

13. 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
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
9.24
1.56
0.16 6
291
06/03/2003
13.30
9.39
8.35
1.54
0.20
7.5
194
06/10/2003
13.70
8.80
8.17
1.47 5
488.4
06/17/2003
16.80
0.21
9.70
8.14
1.55
157
06/24/2003
16.64
7.86
8.07
1.48
0.18
345
𝑭 𝟏 = 𝟐 𝟖 ×𝟏𝟎𝟎= 25.00
𝑭 𝟐 = 𝟏𝟑 𝟓𝟔 ×𝟏𝟎𝟎=𝟐𝟑.𝟐𝟏
𝑭 𝟑  =  𝟎.𝟎𝟐𝟑 𝟎.𝟎𝟏(𝟎.𝟎𝟐𝟑)+𝟎.𝟎𝟏 = 2.24
𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 =  −1 = 0.125, etc.
𝑛𝑠𝑒 =  = 0.023
WQI =100− = = GOOD

14. Assigning quality Class WQI scores Excellent 90-100 Good 70-89.99 Fair
Poor

15. Advantages Disadvantage Any time interval Missing values OK
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
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
9.24
1.56
0.16 6
291
06/03/2003
13.30
9.39
8.35
1.54
0.20
7.5
194
06/10/2003
13.70
8.80
8.17
1.47 5
488.4
06/17/2003
16.80
0.21
9.70
8.14
1.55
157
06/24/2003
16.64
7.86
8.07
1.48
0.18
345
Advantages
Any time interval
Missing values OK
Disadvantage
Skewed by missing parameters

16. Ambient Network Water Quality 2014
2014 ambient network results

17. Nonpoint & point sources

18. Water quality among basins
Just ambient data

19. Trends in the ambient network91

21. Antelope Creek at State Fair Park
WQI increasing mostly from the F1 & F3 components
TP and TSS exceeded less often
Magnitude of exceedances decreased F1 F3

22. Antelope Creek at State Fair Park

23. Pine Creek S. of Rushville
WQI decreasing mostly from the F1 component
TSS exceeded 150 mg/L more frequently
E. coli collected 2014

24. Shell Creek NE of Columbus

25. Shell Creek NE of Columbus

27. North Platte
Grand Island
Lincoln
Sidney
Ogallala

28. R2 = 0.539, P < 0.001

29. R2 = 0.429, P < 0.001
The WQI responds to nonpoint source pollution, and this pollution, in Nebraska, can be represented by the relative amount of rowcrop versus pasture.

30. 35.98, POOR
17.91, POOR
34.61, POOR
36.56, POOR
60.48, FAIR
71.88, GOOD

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

32. Questions?

34. Map of fish habitat risk, fishhabitat.org