1. Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014
Regional Progress in Water Quality ---- A Trend Analysis for Select Streams in the Twin-Cities Metro Area
This study is part of stream assessment report. If you would like to know details about the report, you can stop by our post during the break and our website as well. We have the assessment results for St Croix River tributaries published n our website and other chapters for Missi R and MN r tributaries will be posted soon.
Currently, I am also working on the river water quality assessment report, which will be completed in next one or two years. And by the time, I will be able to present to you the second part of the regional progress in QW ---- rivers.
H. Wang, K. Jensen, J. Kostrzewski, E. Resseger,
T. O’Dea, J. Mulcahy and J. Sventek
Metropolitan Council Environmental Services, St Paul, MN
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

2. Acknowledgements MCES Water Resources Assessment Group
MCES Environmental Monitoring Group
David Lorenz – USGS, Mounds View, MN
Skip Vecchia – USGS, Bismarck, ND
We are working closely with USGS staff to apply the model to the metro streams for water quality trends
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

3. Outline QWTREND Statistical Model and Application
Case Studies - Vermillion River and Bassett Creek
Regional Water Quality Trend and Comparison
Conclusions
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

4. Water Quality Trend --- External Factors ---
Natural Processes
Precipitation/runoff
Seasonal changes
Wet and drought years
Climate changes
Human Activities
Agricultural practices and urban development
BMPs for non-point pollution sources
Point source discharges and control
as you know WQ is affected by many factors. First of course, the natural processes such as precipitation and seasonal variations. Second is human activities. Impacts by those two processes could be complicated . For example, BMPs can reduce pollution loads and improve water quality. however, those efforts can also be offset by increases in surface runoff and flow due to seasonal, annual and long-term climate changes.
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

5. Water Quality Trend --- Trend Types ---
Non-Flow-Adjusted Trends
---- The overall trends resulting from both natural and human factors
Flow-Adjusted Trends
---- The trends that would have occurred in the absence of natural stream flow variability
Therefore, we divide WQ trends into two types of trends: non-flow adjusted and flow adjusted.
In our trend analysis, we are trying to identify the flow-adjusted trend using QWTREND model to remove impact of flow variability
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

6. What is QWTREND? Short for Quality of Water TREND
A statistical program developed by USGS
A time series model accounting for seasonality and complex flow-related variability
Ability to analyze multiple and long-term water quality trends
So what is QWTREND. QWTREND is statistical program --- short of quality of water trend developed by USGS.
The model has been used by USGS for many projects national wide and recently used by MPCA for statewide nitrogen study
Different from traditional methods such as Kendal Tau, which only provide monotonic trend, QWTREND has ability to identify multiple trends for a water body
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

7. QWTREND Model Log C(t) = M + SEAS + SRA + TND + PRDEV + NOISE
M is the long term mean
SEAS is seasonality
SRA is the stream flow-related anomaly
TND is the long-term trend
PRDEV is predicted deviation
Noise is the prediction error
QWTREND models pollutant concentration in logarithm and separate the concentration variability into different components, including trend
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

8. QWTREND Data Requirements
At least 15 years of water quality records
Average of at least 4 samples per year
At least 10 samples within each quarter of the year over a 15-year period
Less than 10% of values below detection limit
Complete daily flow record for the assessment periods plus precedent five years
The model has several minimum data input requirements, in which most important is you have to have at least 15 years QW data, particularly daily flow.
Thanks to the great job of our monitoring group, MC has very good monitoring data. Most meet the requirements
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

9. QWTREND Assessment Criteria
Akaike Information Criteria (AIC)
AIC = (-2lnL) + (2*Parameters)
p-value
p =1-pchisq((-2lnL)initial - (-2ln L)linear, Trends)
p-value for this study: 0.05 for one-trend model
To identify if trend exists, we use two statistical metrics, which are kind of quality control
--- a relative measure of the goodness of fit of a statistical model (AICLinear < AICInitial)
-----an index for statistical significance of the modeled trends (0.1 > P > 0.01)
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

10. Stream Monitoring Stations in the Metro Area
The Metropolitan Council currently collects both water quality and stream flow information at 23 stream sites and some stations started The program covers about 50% of watersheds in the metro areas and provides excellent data set for water quality assessment and management
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

11. Stream Selection and Data Availability
Streams and monitoring stations
9 Mississippi River tributaries
9 Minnesota River tributaries
2 St. Croix River tributaries
Parameters
Total suspended solids
Total phosphorus
Nitrate
Varying water quality records
Based on availability of data, we chosen 20 streams for trend assessment
Those three traditional parameters are assessed to present the WQ
Most streams have more than 15 yr data but few have years
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

12. Case Study (1) --- Vermillion River
One of the largest tributaries
Empire WWTP discharged to the river since
TP impacted by effluent
Bio-P removal applied from 2006
Trout stream
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

13. Case Study (1) --- Vermillion River
TSS
One downward trend with 65% decrease
Last 5 yr: decreased by 19% at 0.33 mg/l/yr in the
Decreasing TSS
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

14. Case Study (1) --- Vermillion RiverTP
: increased by 76%
2006 : sharply decreased by 89%
2007 – 2008: slow decreased by 28%
2009 – 2012: faster decreased by 45%
Last 5 yr: decreased by 53% at 0.01 mg/l/yr
Decreasing TP
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

15. Case Study (1) --- Vermillion River
Nitrate
: increased by 89%
2001 – 2012: decreased by 49%
Last 5 yr: decreased by 21% at 0.19 mg/l/yr
Decreasing nitrate
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

16. Case Study (2) --- Bassett Creek
Urbanized watershed (64%)
No major point sources
A number of BMPS implemented
Storm water ponds
Channel restorations
Herbicide application
a number of water quality improvements have been made within the watershed. Water quality ponds were constructed to treat stormwater runoff
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

17. Case Study (2) --- Bassett CreekTP
TSS
NO3
Cl-
a number of water quality improvements have been made within the watershed. Water quality ponds were constructed to treat stormwater runoff
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

18. Deterioration Improvement
Regional Progress in WQ Mississippi River Tributaries (2008 – 2012) ----
Deterioration Improvement
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

19. Deterioration Improvement
Regional Progress in WQ Minnesota and St. Croix River Tributaries (2008 – 2012) ----
Deterioration Improvement
Sand Creek TSS actually fluctuated during the assessment period from 1990 to But a unfortunately TSS increase during the last five years probably due to heavy storm and bank failure.
No TP and nitrate trends were reported for Eagle Creek, and no TP trend was for Willow Creek
Increasing TSS and TP trends in Browns Creek are likely due to the disturbance of sediment and soil during the construction phase of major stream restoration projects.
Valley Creek has substantial ground water nitrate contribution.
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

20. Regional Map of Modeled Trend ---- TSS Concentration ----
Three colors
Blue represent concentrations decreased more than -3%
Yellow represent the concentration varied with -3% - 3%
Red represent the concentration increased more than 3%
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

21. Regional Map of Modeled Trend ---- TP Concentration ----
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

22. Regional Map of Modeled Trend ---- Nitrate Concentration ----
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

23. Potential Factors Linked to Improving WQ
The Clean Water Act in 1972
State-wide reduction in wastewater treatment plant (WWTP) phosphorus discharges
The Minnesota Phosphorus Lawn Fertilizer Law implemented in 2002
Ag programs
The Metropolitan Surface Water Management Act in 1982
Educational programs
Grants to fund construction of water quality practices
Environmental non-profits
The Minnesota State Storm-water Manual in 2005
People may interest in to know what contributes to our great progress in WQ regional wide.
To link the trends to the cause, we need work closed with local watershed management organization.
But in general, I believe that many pollution control and management programs are contributing this improvement.
They include federal level the clean water Act which push impaired water assessment and TMDL study, and also many state, regional and watershed level programs, efforts by non-profit organization and so on.
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

24. Conclusions
Of the 20 streams assessed, most exhibited a substantial improvement in water quality
17 showed decreasing TSS and TP concentrations
16 had decreasing NO3 concentration
None of the streams had decreasing water quality for all three parameters
There was no identifiable spatial pattern for the streams with increasing or decreasing water quality
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014

25. Thank You! Question? Dr. Hong Wang Principal Environmental Scientist
Metropolitan Council  Environmental Services
P   |  F
390 North Robert Street, St. Paul, MN55101
metrocouncil.org
      
Presented to Minnesota Water Resources Conference Oct 14 – 15, 2014