-- Remember only 30% of all days are on weekends, so if you have a job, family or life cut all "boatable days" down by 70% and thats whats left for you!
I just completed a statistical analysis of the number of boatable days on the Upper Chattooga using the USGS's daily mean flow data for the years 1940-2007. I did counts of the number of days the flows would meet specific criteria under 16 different scenarios. The criteria include the minimum boatable flow (1000 cfs near Clayton -- a little under the minimum flow during the flow study -- and 1450 cfs -- the USFS's guess as to the flow near Clayton that corresponds to 450 cfs at Burrells Ford Bridge), the maximum boatable flow (based on experience on similar reaches, approximately three times the minimum flow, or 3000 cfs near Clayton), the annual time period in which boating is allowed (all year and 12/1-3/1), and whether a boatable flow occurs a day after a boatable flow has occurred (on the assumption that it is more likely the USFS will recognize, and paddlers will have time to react, to a boatable flow and actually boat it).
Here's what I find to be the most interesting results:
1. If the ban was completely lifted, the expected value of the annual number of boatable days on the Upper Chattooga is 53.1 (this is the mean, AKA "average," of the sample); the median of the sample is 52.5 days (half the years in the 68 year sample had boatable days above this number and half below it), the mode is 56 days (the most common number of boatable days in the years included in the sample). The number of boatable days in a given year ranged from 5 to 165. Obviously there is a lot of variation in the number of boatable days. This is made even more clear by the standard deviation of 35.9, which is quite high relative to the mean of 53.1. Who would have guessed there would be so much variation in the number of high flow days .
2. If the ban is modified in the way the USFS proposes (1450 cfs minimum flow, what boating is allowed is only allowed 12/1-3/1), the expected value of the annual number of boatable days on the Upper Chattooga is 6.3 days. The median under this scenario is 4.5, the mode 3, the range 0-19 and the standard deviation 5.3 (which is very very high relative to the mean of 6.3).
3. If the ban is modified to allow boaters to choose when to boat within a seasonal window (all but Louie choosing to boat on days of 1000 cfs or higher, what boating is allowed is only allowed 12/1-3/1), the expected value of the annual number of boatable days on the Upper Chattooga is 18.6. The median under this scenario is 12.5, the mode 10, the range 1-58 and the standard deviation 14.6 (which is also very very high relative to the mean of 18.6).
4. Adding the assumption that "boatable flows" are most likely to be boated when they occur on days following boatable flows reduces the number of "boatable days" dramatically. For example, if the ban is modified in the way the USGS proposes, the mean number of boatable days drops from 6.3 to 3.5; the median from 4.5 to 2.0, and the mode (the most frequent event) from 3 to 0.
BoaterTalk 
