1. LONG-TERM WATER QUALITY DATA AND BIOGEOCHEMICAL FILTERING ALONG THE UPPER CLARK FORK RIVER, MT, USA. H. Maurice Valett 1 Marc Peipoch 1 Mike DeGrandpre 2 Vicki Watson 3 Mike Suplee 3,4 Rob Payn 5 1 Div. of Biological Sciences, University of Montana 2 Dept. of Chemistry and Biochemistry, University of Montana 3 Environmental Sciences Program, University of Montana 4 Montana Dept. of Environmental Quality, Helena, MT 5 Dept. of Land Resources and Environmental Science, Montana State University

2. THE CLARK FORK RIVER, MT - largest river by volume in Montana - Class I river for recreation from Warm Springs Cr. to the Idaho border

3. The Clark Fork/Milltown Superfund /Silver Bow (megafund) Site 1 2 3 4

4. Upper Clark Fork River OU Milltown Dam OU Reach A Reach B Reach C

5. Voluntary Nutrient Reduction Program (VNRP) sites: Clark Fork River from Butte to Lake Pend Oreille

6. Nutrients in the Upper Clark Fork River How have river nutrient conditions changed over the past 30 years? How can monitoring records be used to understand current biogeochemical functioning of the UCFR? How will nutrient conditions influence ecological restoration of lotic biota and processes?

7. Missoula Anaconda Butte USGS Flow Gauges Along the UCFR

8. Missoula Anaconda Butte 7 9 10 11 12 13 Voluntary Nutrient Reduction Program (VNRP) sites River Q: 1984 – 2014 Water chem (N & P): Period I: 1986-1992 Period II: 1999-2001 Period III: 2005

9. 2005-2009 1998-2004 0 450 300 150 Total N (μg/L) Modified from Suplee et al. (2012) 0 200 400 Algal Chl a (mg/m 2 ) Site 9Site 10Site 12Site 15.5 60 30 0 Total P (μg/L) Water quality criteria relate to nutrient concentrations. …its what biota ‘see’. UCFR – spatial and temporal trends in N and P But, what causes change?

10. Galen (7) Deer Ldg (9) Garrison (10) Drummond (11) Gold Cr (12) Turah (13) UCFR Discharge Record (1984-2013): a gaining river system +ΔQ with downstream progression

11. Nutrient Flux (F) and Load (L): concentration (mass/vol) discharge (vol/time) flux (mass/time) flux (mass/time) time (time) load (mass)

12. UCFR TN flux increases with distance downstream Total N flux : 1986 – 1992 (7 years) (Mg/month)

13. UCFR TP flux increases with distance downstream Total P flux : 1986 – 1992 (7 years) (Mg/month)

14. UCFR SRP flux increases with distance downstream Soluble Reactive P flux : 1986 – 1992 (7 years) (Mg/month)

15. UCFR nitrate flux varies with distance downstream Nitrate flux : 1986 – 1992 (7 years) Most of the increase happens at the head of the continuum… especially during winter. (Mg/month)

16. Nitrate flux : 1986 – 1992 (years) In some places nitrate flux decreases with distance downstream (Mg/month)

17. Missoula Anaconda Butte 7 9 10 11 12 13 Voluntary Nutrient Reduction Program (VNRP) sites Little Blackfoot River Deer Lodge Garrison Gold Creek Bonita Turah Warm Springs WSTPs

18. Nitrate flux : 1999 – 2001 (3 years) UCFR nitrate flux decreases in the same locations and with patterns similar to 10 years earlier (Mg/month)

19. UCFR TN flux increases with distance downstream with patterns similar to 10 years earlier Total N flux : 1999 – 2001 (3 years) (Mg/month)

20. Nitrate flux : 2005 (1 year) UCFR nitrate flux decreases in the same locations and with patterns similar to 10 years earlier (Mg/month)

21. 1986-19921999-20012005 Riverine hotspot for NO 3 - removal: variation in space and time 7 9 10 12 Biota! (Mg/month)

22. 2005-2009 1998-2004 0 450 300 150 Total N (μg/L) Modified from Suplee et al. (2012) 0 200 400 Algal Chl a (mg/m 2 ) Site 9Site 10Site 12Site 15.5 60 30 0 Total P (μg/L) But what is it that what biota ‘see’? Water quality criteria relate to Total N and Total P. Act as reservoirs for more bioavailable forms.

23. Relative abundance of inorganic (i.e., reactive) N and P change seasonally Atomic N:P where: N = DIN = NO 2 - + NO 3 - + NH 4 + P = orthophosphate

24. Atomic N:P 0 10 20 30 Warm Springs (7) 0 100 200 300 Deer Lodge (9) JMSDMJNFAJAO 0 40 80 Gold Creek (11) Winter: P-limitation Summer: N-limitation Relative abundance of inorganic (i.e., reactive) N and P change seasonally

25. green algae (Cladophora) - nutrient-rich - high N concentrations

26. bluegreen algae (bacteria) - P-rich - low N concentrations N Nostoc

27. Conclusions  Declining concentrations – evidence of management success  Seasonal variation in river N and P flux = differential connections  Declining N0 3 -N flux = biological self-purification?  algal uptake vs. denitrification  Role of biological N-fixation  Floodplain restoration and influences on C, N, and P dynamics

28. Current monitoring along the UCFR MT DEQ maintains monitoring of water quality in the UCFR at a reduced number of sites from June to September …concomitant monitoring of benthic algal standing crops (Vicki Watson, UM, MT DEQ)