Nebraska. Water Quality. Index. Page 2. A water quality index is⦠⢠A single value, from 0 â 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