In all variables, but
especially in CH4_LEL and O2, the number of Southern Ute
Reservation sites showing significant trends was far more than could be
explained by chance variations (assuming the readings at each site were
statistically independent). Of the
sites showing significant trends in CH4_LEL, the number of upward
trending sites dominated the number of downward trending sites in a much larger
proportion than could be explained by chance (assuming independence at all
sites with trend). The number of sites
showing downward trends in O2 significantly outnumbered those
showing upward trends. (It is expected that O2 will decrease as
other gases increase.) The number of
sites showing upward trends in H2S dominated those showing downward
trends, but the proportion was less dramatic. Although significantly many of
the reservation sites showed trends in flow, no clear pattern emerged between
upward trending and downward trending flows.
At off-reservation sites,
only O2 measurements showed more significant trends than could be
explained by chance. At the sites with
significant trends in O2, increases significantly dominated
decreases. This is the opposite of the
pattern on the reservation sites; however, the off-reservation increases in
oxygen seem to be relatively small in magnitude. Monitoring at these sites has been going on for a much shorter
period, and it is not unreasonable to expect that the lack of other significant
trends is merely an artifact of insufficient data.