1. Hydrologic Change in the Lower Flint River Basin and Responses of Freshwater Mussels to Drought S.W. Golladay and D.W. Hicks J. W. Jones Ecological Research Center, Newton GA

2. Study Area Spring Ichawaynochaway Lower Flint Kinchafoonee and Muckalee Recharge Area Upper Floridan Aquifer

3. Rainfall = 52 inches/year i Runoff = 7 inches/year Recharge = 10 inches/year SW Georgia Hydrologic Cycle Flint ET = 35 inches/year Upper Floridan Aquifer

4. Why Mussels? - High diversity and endemism long recognized (Clench and Turner 1950’s) - Important to stream function - Sensitive indicators of stream degradation -Long term population declines and extinctions occurring - Named in litigation concerning water allocation and ESA

5. Jones Center Studies 1999 - 46 sites on 12 tributaries - 14,873 mussels - 19 species found (of 29 historical) - 3 endangered species Shiny-rayed Pocketbook Gulf Moccasinshell Oval pigtoe

6. 2001 Post Drought Survey Objectives: 1) Determine the extent of regional changes in mussel assemblages due to the drought 2) Determine stream reaches likely to be adversely affected by drought

7. Site Selection Criteria for Selection - 20 sites surveyed - Previously surveyed in 1999 - Previously supported diverse or abundant mussel populations - Represent a range of stream size Muckalee Ck Kinchafoonee Ck Chickasawhatchee Ck Spring Ck

8. Results Hydrologic and Geologic Classification Fall Line Hills Dougherty Plain Fall Line Hills Muckalee Ck Kinchafoonee Ck Chickasawhatchee Ck Spring Ck

9. Box Plot of Mussel Abundance Mann-Whitney Rank Sum Test p=0.05

10. Changes in Mussel Abundance 1999 to 2001 Muckalee Ck Kinchafoonee Ck Chickasawhatchee Ck Spring Ck

11. Status of Mussels 1999 to 2001 Common Species Elliptio complanata Elliptio crassidens Toxolasma paulus Uniomerus carolinianus Villosa lienosa Villosa vibex 1999 (#/site)2001 (#/site) Flowing226314p=0.02 Non-Flowing181 71p=0.01

12. Status of Mussels 1999 to 2001 Endangered Species Hamotia subangulata Sites 11/7 Medionidus pencillatus Sites 2/1 Pleurobema pyriforme Sites 5/6 1999 (#/site)2001 (#/site) Flowing 3 6p=0.2 Non-Flowing27 2p=0.1

13. Status of Mussels 1999 to 2001 Special Concern Species Elliptio purpurella Lampsilis claibornensis Quadrula infucata Strophitus subvexus Villosa villosa 1999 (#/site)2001 (#/site) Flowing 20 22p=0.6 Non-Flowing 3 1p=0.7

14. Conclusions Mussel mortality occurs during periods of low flow Many mussel species are uncommon Remaining populations are isolated Questions Water use is high in the lower Flint, are we contributing to stream drying? Was the 2000 drought unusual? Is climate (rainfall) changing? What is the extent of water use? Are stream flows changing and associated with water use?

15. Expansion of Irrigation Data from: Harrison, K.A. and A.W. Tyson. 2001. Irrigation survey for Georgia. Proceedings of Georgia Water Resource Conference.

16. Climate Analysis - Monthly drought and rainfall data from NCDC region 7 - Historical drought frequency - Compared pre- and post irrigation annual and seasonal rainfall - 10 yr running averages for seasonal

17. Hydrologic Analysis conserveonline.org - Compared pre- and post irrigation flows (using 1975 as the beginning of irrigation) - 1, 7, 30 day minimum flows - 50 percentile flows

18. Long Term Gauging Stations

19. Rainfall Trends

20. Palmer Drought Severity 1940 - 2008 Drought of Record

21. Lowest flow of record ??

22. Regional Rainfall -- Annual Least annual rainfall - Little annual change - Least annual rainfall during 1950’s drought

23. Regional Rainfall -- Seasonal 10 year running average

24. Potential Human Impacts Regional land-use 50-60% agriculture and mostly irrigated

25. Groundwater Permits Permitted 413 Mgal/d Actual ~ 90 Mgal/d Permitted 1.34 Bgal/d Actual ~ 177 Mgal/d

26. Surface Water Permits Permitted 368 Mgal/d Actual ~ 48 Mgal/d Minimal

27. Streamflow Trends

28. Spring Creek - 46% decline in 1 day minimum flows - 39% decline in 7 day minimum flows - 42% decline in 30 day minimum flows

29. Ichawaynochaway Creek - 40% decline in 1 day minimum flows - 31% decline in 7 day minimum flows - 9% decline in 30 day minimum flows

30. 50 Percentile Flows Loss of Storage?

31. Erosion and Runoff

32. Erosion and accelerated runoff Excessive sediment Spring Creek Watershed

33. Changes in the lower Flint River Basin - Declining mussel populations - Increasing isolation of mussel populations - Declining minimum daily flows - Altered seasonality of flows Water use contributes to declining stream flows Derivative indices (e.g. 7Q10) are changing.

34. Questions? Freshwater Mussel migrating during drought