Draft Environmental Impact Statement for Roca Honda Mine

Chapter 3. Affected Environment and Environmental Consequences
thicker in some areas (OSE, 2008). Most alluvial well completions also include some of the
underlying Menefee Formation.
Groundwater in the alluvium is unconfined. Locally it may be perched above the regional water
level by relatively impermeable shale and siltstone in the underlying Menefee. GMRC (1979b)
suggests that springs in the valley may have this mechanism as their origin.
Thirty-one wells completed in the alluvium were identified in the inventory, most of which are in
the area of the community of San Mateo. The closest alluvial “well” to the permit area is No. 19
(OSE file number B-00557) near Bridge Spring and the south margin of Section 21, the section
due south of Section 16 in the permit area. Review of OSE records suggests that this item in the
inventory was actually a sump in the alluvium pumped to provide water for construction of a
bridge in the late 1970s.
Water quality data from historic sources or RHR monitoring are available from six wells in the
alluvium. The water is of the sodium-bicarbonate-sulfate type. TDS ranged from 365 to 1,610
mg/L, with five of the wells having at least one sample exceeding the SDWA Secondary
Standards for manganese and TDS, and four having at least one sample exceeding the Secondary
Standard for sulfate. SDWA Primary Standards for gross alpha radiation and uranium were
exceeded in two wells and one well, respectively; a third well exceeded the Action Level for lead.
Tables 9-1 and 9-2 of the BDR summarize the data, and figure 9-11 shows the locations of the
wells sampled.
Springs
Springs represent visible, specific locations of groundwater discharge to the land surface; this is
distinct from baseflow, which is a groundwater discharge to a stream that occurs out of sight and
gradually along a stream length. RHR has conducted an intensive survey of San Mateo Creek,
which included investigation of on-channel springs in the area (Hydroscience Associates, Inc.
(2010); the Intera modeling effort for RHR identified a large number of springs within the
modeled area (Intera, 2011b, 2012). Based on project scoping, there is particular concern for one
set of springs not included in the area modeled, specifically Horace Springs and related springs
along the Rio San José at Acoma Pueblo, and also including Ojo del Gallo at San Rafael. Both the
inventoried and Rio San José springs are discussed below.
Springs in the RHR Inventory
Over 100 springs have been identified within 50 miles of the RHR permit area (Intera, 2012).
Figure 40 is a map of spring locations. Forty-one of the springs discharge directly from the
volcanic rocks of Mt. Taylor and Mesa Chivato (typically where basalts overly ashbeds) and 20
springs are associated with the contact of the Mt Taylor-Chivato Mesa volcanic platform with the
underlying sedimentary volcanic rocks. Many of these Mt. Taylor springs are reported to be
perennial. The springs associated with the volcanic platform occur between 6,800 and 11,000 feet
in elevation and are the result of rain and snowmelt seeping into fractures and flowing by gravity
through the volcanic rocks (Intera, 2012). Some of the springs within 10 miles of the RHR permit
area that get their water from volcanic rocks are Tecolote, Diablo, San Mateo, Marquez,
Guadalupe, Salado, Moses, Jaralosa, and Canoa Springs. Additionally, El Rito, La Mosca, Cliff,
Pine, Pumice, San Miguel and Maruca Springs emanate from the contact between volcanics and
landslide materials (Intera, 2012). NMEI estimated the flow of the springs above San Mateo to
average 0.5 cfs or 360 acre-feet per year; in recent years the springs have produced little flow.
DEIS for Roca Honda Mine, Cibola National Forest 139