Level 4 Potential Conservation Area (PCA) Report
Name
Alamosa River at De La Luz Cemetery
Site ID
1423
Site Code
S.USCOHP*20091
IDENTIFIERS
Site Class
PCA
None
Site Alias
Network of Conservation Areas (NCA)
NCA Site ID
NCA Site Code
-
NCA Site Name
No Data
County
Conejos (CO)
SITE DESCRIPTION
Minimum Elevation
8,100.00 Feet
2,469.00
Meters
Maximum Elevation
8,160.00
2,487.00
Meters
Feet
Site Description
This site contains submergent, wet meadow, and riparian habitat along the Alamosa River, and occurs at the
meeting of the foothills of the San Juan Mountains and the San Luis Valley floor. Topography of the site is
relatively flat. This riparian/wetland complex is maintained by flows in the Alamosa River and the high
groundwater table located in the narrow floodplain. Terrace Reservoir, which lies approximately four miles
upstream, has greatly changed the hydrology of this site. Although periodic flooding does occur on the
Alamosa River (often ditch companies are not diverting water in late spring), the volume of peak floods has
been reduced by the presence of the reservoir (Stern 1997). Reservoirs often do not allow sediment to pass
through the impoundment, which, in addition to channelization, causes the river downstream to scour the
banks and the river bottom until its bed load has reached equilibrium with the sediment carrying capacity of the
river (Federal Interagency Stream Restoration Working Group, 1998). This process causes the river channel
to become incised, lowering local water tables and destroying riparian and floodplain habitat (Federal
Interagency Stream Restoration Working Group 1998). Near the upstream end of the site, an abandoned
irrigation headgate sits almost 10 feet higher than the current level of the river due to these processes.
Although current hydrological conditions appear to be supporting the elements, the incision of the river
channel and subsequent reduction in seasonal flooding limits the ability of these communities to regenerate on
a scale that would maintain viable occurrences in the long-term. For example, the local groundwater table
does not appear to have been lowered enough to negatively affect the floating/submergent wetland
community. However seasonal flooding is necessary for creating the proper geomorphic setting for
populations of cottonwood to establish, such as a sinuous river system (e.g., oxbows) and flood channel
scouring. Narrowleaf cottonwood (Populus angustifolia) and thinleaf alder (Alnus incana) are the dominant
species along the riverbank, forming a long, narrow riparian community. Wet meadows occur within the
floodplain with graminoids, such as Baltic rush (Juncus balticus) and timothy (Phleum pratense), and mixed
forbs dominating these areas. Exotics such as Cirsium arvense and Bromus inermis are also present. A small
slough (old oxbow) occurs on the south side of the river where beaked sedge ( Carex utriculata) occupies the
margins and narrow-leaved bur-reed (Sparganium angustifolium) occurs in open water areas. Adjacent upland
areas are dominated by Chrysothamnus. Grazing has not occurred on the site (at least South of the river) in
the past five years; as a result vegetation growth is dense and tall. Early explorers to the San Luis Valley noted
"crops of rank sedges and grasses" and "rich, dark grasses" growing along many riparian areas (Essington
1996). Based on these statements and on observations of understory growth in other healthy riparian areas
(e.g., McIntire Springs), this site could serve as a reference site for restoration efforts along the Alamosa River
downstream of this location. Downstream from this site there is heavy grazing along the river, deep
channelized banks, and many diversions.
Key Environmental Factors
Seasonal flooding, water quality of Alamosa River, downcutting of Alamosa River.
Climate Description
No Data
Land Use History
Historically grazed with sheep. An old headgate is also located along river, however water is no longer diverted
via this headgate as the Alamosa River has downcut below the elevation of the headgate.
Copyright © 2017. Colorado State University. Colorado Natural Heritage Program. All Rights Reserved.
Print Date
3/4/2017
1
Level 4 Potential Conservation Area (PCA) Report
Name
Alamosa River at De La Luz Cemetery
Site Code
S.USCOHP*20091
Cultural Features
An old adobe structure exists on site. Old farming equipment was also located.
SITE DESIGN
Site Map
Y - Yes
Designer
Rocchio, F.J.
Mapped Date
12/14/1999
Boundary Justification
The site boundary includes the immediate floodplain and a secondary floodplain terrace to allow the river to
continue its geomorphic processes when possible (i.e., water releases from Terrace Reservoir). The
boundary was drawn to account for natural processes such as allowing the Alamosa River to meander,
thereby creating new potential habitat for riparian communities and ensuring seasonal flooding which is
critical to maintaining the elements at this site. The boundary also encompasses immediate nearby slopes
and adjacent upland areas that contribute surface and possibly groundwater flow to this riparian ecosystem.
Although grazing appears to be minimal on adjacent properties, the boundary provides a buffer against
potential impacts of this activity by filtering surface water runoff from heavy nutrient and sediment loads that
could potentially affect the elements, and protection from excessive trampling and browsing. It should be
noted that although upstream portions of the Alamosa River were not included within the site boundary, but
these areas and the ecological processes they support are vital to the viability of the elements.
279.92 Acres
Primary Area
113.28 Hectares
SITE SIGNIFICANCE
Biodiversity Significance Rank
B3: High Biodiversity Significance
Biodiversity Significance Comments
The Alamosa River at De la Luz Cemetery site supports one good example of a riparian plant community
vulnerable on a global scale and one fair example of a submergent wetland plant community whose global
rank is unknown at this time.
Other Values Rank
No Data
Other Values Comments
No Data
ASSOCIATED ELEMENTS OF BIODIVERSITY
Element
State ID
19341
24541
State Scientific Name
State Common Name
Sparganium angustifolium Herbaceous
Vegetation
Populus angustifolia / Alnus incana Woodland
Montane Floating/submergent
Palustrine Wetlands
Montane Riparian Forest
Global
Rank
State
Rank
Driving
Site Rank
G4
S2
N
G3
S3
Y
LAND MANAGMENT ISSUES
Land Use Comments
No Data
Natural Hazard Comments
No Data
Exotics Comments
No Data
Offsite
No Data
Information Needs
No Data
REFERENCES
Reference ID
Full Citation
165924
Kettler, S., J. Rocchio, R. Schorr, J. Burt. 2000. Biological Inventory of Rio Grande
and Conejos Counties, Colorado. Unpublished report prepared for The Nature
Conservancy. 234 pp.
Rocchio, J. 1999. Colorado Natural Heritage Program Wetland and Riparian
Inventory/Assessment for Rio Grande/Conejos Counties.
171089
Copyright © 2017. Colorado State University. Colorado Natural Heritage Program. All Rights Reserved.
Print Date
3/4/2017
2
Level 4 Potential Conservation Area (PCA) Report
Name
Alamosa River at De La Luz Cemetery
Site Code
S.USCOHP*20091
ADDITIONAL TOPICS
Additional Topics
No Data
LOCATORS
Nation
United States
Latitude
State
Colorado
Longitude
Quad Code
Quad Name
37106-C2
Centro
Watershed Code
Watershed Name
13010002
Alamosa-Trinchera
371953N
1061211W
VERSION
Version Date
12/14/1999
Version Author
Rocchio, F.J.
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Copyright © 2017. Colorado State University. Colorado Natural Heritage Program. All Rights Reserved.
Print Date
3/4/2017
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