FLOOD10357

• Document ID: 123
• County: Rio Grande
• Stream Name: Alamosa River
• Basin: Rio Grande
• Sub-Basin: Alamosa - Trinchera
• Water Division: 3
• Title: Alamosa River Watershed Project Literature and Watershed Assesment, Final EPA Report
• Date: 9/30/2003
• Prepared For: Valle del Sol Community Center
• Prepared By: US Environmental Protection Agency
• Watershed Pro - Doc Type: Project Report

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Alamosa River Watershed Water Resources

Year round streamflow on the Alamosa River is an important decision point for the
watershed. If there is a decision to investigate year round stream flow studies, there
needs to be a minimum stream flow study performed to determine what streamflow is
necessary to support aquatic life. The watershed restoration plan should develop an
acceptable minimum streamflow approach in cooperation with the CDOW (John Alves)
to determine what flows will support fish survival.

There is limited, if any, streamflow data collected on the Alamosa River downstream of
Terrace Reservoir at the former USGS gaging station. The hydrology of the lower
portion of the river needs to be monitored more closely to better characterize the loss of
stream flow to the aquifer above Capulin and the gain of water downstream toward US
285. Streamflow information will be important to understanding the recharge to the
aquifer and approaches needed to raise the aquifer's level.

There is a concern about the level of the groundwater decreasing, especially since the
channel straightening project performed by the Army Corps of Engineers. This study is
not aware of any hydro-geologic studies in the lower portions of the watershed that show
groundwater flow velocities, groundwater direction, recharge areas, depth of
groundwater, depletion rate of groundwater and elevation. Efforts should be taken to
initiate groundwater elevation monitoring to understand the groundwater elevation
changes per time and the relationship with Alamosa River stream flow. This information
will be useful in understanding the aquifer and developing remedial strategies to
increase the elevation of groundwater.

According to the Clean Water Act, a TMDL must be performed on any surface water that
does not meet designated water quality uses and standards. There are six segments of
the Alamosa River that do not meet water quality standards and one segment that is on
the Monitoring and Evaluation List (although no monitoring occurs). To date, no TMDL
study has been performed by the CDPHE WQCD even though the Site Remediation
ROD for the Summitville Mine has been developed and signed. It seems logical that the
TMDL should be performed before the water treatment design is finalized to ensure that
the projected metal loading will meet downstream water quality standards. There are
concerns within CDPHE that the designated uses and standards can never be obtained
in some segments regardless of the SDI water treatment.

Physical, chemical and biological water quality monitoring is lacking in the Alamosa
River. The frequency of sampling performed by the CDPHE WQCD is not sufficient to
determine compliance to water quality standards or to establish any water quality trends.
Chemical water quality monitoring performed by the WQCD consists of grab sampling
without the collection of stream flow; therefore, no mass loading of chemicals (pounds
per day) can be determined. Routine monitoring of the Alamosa River needs to be
performed to determine if water quality standards are being met, especially in the lower
portions of the watershed. It is not known if the data collected by CDPHE is stored in the
EPA database called STORET.

No biological monitoring data below Terrace Reservoir was found for this report. The
instream biological assessments are very important indicators of a stream's health. The
presence or absence of macroinvertebrate species, diversity and population densities

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