1. Impacts of Low-Flow Rates on Recreational Rafting Traffic on the Colorado River in Grand Canyon National Park Catherine A. Roberts Joanna A. Bieri

2. Basic Information Bureau of Reclamation, Grand Canyon Monitoring and Research Center (IA # 00-AA-40-4330) Cooperative agreement between Grand Canyon National Park & Northern Arizona University (CA#8210-99-002)

3. Contact Information Catherine A. Roberts Dept. Mathematics & Computer Science Holy Cross College Worcester, MA 01610 croberts@mathcs.holycross.edu Joanna A. Bieri Dept. Mathematics & Statistics Northern Arizona University Flagstaff, AZ 86011-5717 jab34@dana.ucc.nau.edu

4. Low Summer Steady Flow (LSSF) 17,000 - 19,000 cfs in April and May Four days of 31,000 cfs in early May Steady 8,000 cfs June - September Four days of 31,000 cfs in early September Glen Canyon dam releases during summer 2000

5. Objective of Study To examine the impact of LSSF on recreational rafting traffic on the Colorado River within the Grand Canyon National Park.

6. Outline of the Study Collect Trip Reports during LSSF. Place information into database. Compare “low flow” data to “typical flow” data collected during 1998/1999.

7. Trip Report

8. Trip & Flow Classifications Commercial = C Private = P Trip Length = days between Lees Ferry (river mile 0) and Diamond Creek (river mile 225.7). Low Flow = LSSF (8,000 cfs) Typical Flow = 1998/1999 (19,000 cfs)

9. Four Trip Types Motor –Short 8 or fewer days –Long 9 or more days Oar –Short 14 or fewer days –Long 15 or more days

10. Low Flow Trip Reports Short Motor 61 C, 0 P Long Motor 3 C, 3 P Short Oar 23 C, 2 P Long Oar 10 C, 18 P TOTAL = 120 Trip Reports 599 launches 20% return rate

11. Typical Flow Trip Reports Short Motor 222 C, 7 P Long Motor 18 C, 9 P Short Oar 64 C, 24 P Long Oar 18 C, 125 P TOTAL = 487 Trip Reports 1,689 launches 29% return rate

12. Boat Speed Low vs. Typical Flow

13. Boat Speed: Short Motor

14. Boat Speed: Long Motor

15. Boat Speed: Short Oar

16. Boat Speed: Long Oar

17. Average Daily Miles

18. Daily Number of Activities

19. Daily Time Spent on Activities

21. Conclusions No change in number of activities/day No change in number of miles/day Boats spent more time on water Boat speeds slower 50% reduction in time spent on activities

22. What’s Next? Analysis of campsite and activity visitation frequencies for “low” and “typical” flows. Final report to GCMRC Several graphs posted on our website: http://odin.math.nau.edu/~msl