REP01579

• Permit No: C1981028
• IBM Index Class Name: Report
• Doc Date: 2/27/2006
• Doc Name: 2005 Annual Hydrology & Annual Reclamation Report
• Annual Report Year: 2005
• Permit Index Doc Type: Hydrology Report
• Media Type: D
• Archive: No

Cumulative precipitation for the January-July 2005 period was 7.78 inches. Precipitation
relevant to the growing season occurs from September to the following July. Total
cumulative precipitation for the period from September 2004-July 2005 was 10.78 inches.
• Compazed to their corresponding averages, these values represent a 5.1 percent increase from
the yeazly precipitation mean (corrected for 2005 precipitation), and a 6.4 percent
(September-July) decrease from the corresponding period in 2004. The precipitation regime
for this yeaz (2005) overall was average with dryer than average conditions from December
2004 through Mazch of 2005 and July through September of 2005. Significant pulses of
precipitation in April and June 2005 favored early growth of cool season graminoids and
annual forbs. Drying conditions from July through September inhibited the growth of the
warm season components of both the reclamation azeas and the reference area.
4.2 VEGETATION COVER
In the azeas with quantitative sample records prior to this year (Osgood sand reference area,
1998 reseeded or interseeded azeas, 1999 reclamation azeas) total vegetation cover increased
in 2005 (Table 13). The 1998 areas increased their cover by 24 percent and the 1999
reclamation areas increased their cover by 57 percent. The Osgood sand reference azea saw
an increase in total vegetation cover of 73 percent from 2004. These changes can be
attributed to the precipitation distribution described above. The lack of autumn 2004 and
summer 2005 precipitation may have hampered moisture and biomass production in the
warm season component this yeaz. Above average April and June 2005 precipitation (29%
and 46% respectively) encouraged the eazly cool season component growth, but the lack of
continued precipitation through the growing season resulted in less vigorous gowth by the
• later perennial cool season and warm season components. Relative cover values for Bromus
tectorum in the 1998, 1999, and the Osgood sand reference area increased significantly from
2004 to 2005 (Table 14). Increases from 2004 values ranged from a 158% increase in
Bromus tectorum in the Osgood sand reference area to a 332% increase in the 1998 areas.
The opposite was true for the annual forb Kochia scoparia. In the reclamation areas this
season, Kochia relative cover significantly decreased, with decreases in relative cover ranging
from 93.8 percent (1998 reseeded or interseeded areas) to 97.4 percent (1999 reclamation
areas) compazed to 2004. While designated a cool season species, Kochia flowers from July
to September, providing one explanation for reductions in cover when considering this yeaz's
precipitation regime and increased competition from species such as Bromus tectorum.
For the purposes of direct comparison, quantitative cover data is present (Table 13) for the
1998 reseeded or interseeded azeas (1999-2005), the 1999 reclamation azeas (2003-2005),
and the Osgood sand reference area (1994-2005).
Variation in mean total vegetation cover in the reclamation areas revealed a total range of six
percent this growing season. Total vegetation cover within the reclamation azeas ranged from
57.60 percent (1998 reseeded or interseeded areas) to 51.40 percent (1999 reclamation azeas).
The Osgood sand reference area claimed total vegetation cover levels greater than the
reclamation areas with 60.40 percent total vegetation cover.
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Coors Energy Company Keenesburg Mine Page 22
2005 Revegetation Monitoring Report