Watershed Protection

Everyone needs clean water to survive and thrive. That’s why the Silver City Watershed Keepers organizes our community to take care of this most valuable resource.

San Vicente Creek is identified as a significant groundwater recharge zone for the northwestern part of the greater Mimbres Basin, one of two groundwater sources for Silver City’s drinking water supply. Wildlife and migratory birds, including the state-threatened Mexican Blackhawk, depend on our watershed’s riparian corridor for breeding, nesting, and forage habitat.

How do we keep our watershed healthy for all?

Water Quality Monitoring

The Silver City Watershed Keepers quarterly water quality monitoring measures pollutants and other metrics from non-point sources, such as sewage leaks, animal and pet waste, and roadways that may be harming San Vicente and Pinos Altos Creeks. Water quality measurements are compared to state Water Quality Act standards to evaluate the health of our streams. By collecting water quality data over time, we can understand threats to our watershed and develop solutions to restore and protect it.

Silver City Watershed Keepers has been monitoring water quality at four stations along San Vicente Creek for more than a decade. An additional site has been recently added on Pinos Altos Creek. Water quality data is important to assess and evaluate the health of the watershed and to identify potential problems within the watershed.

The four established sites on San Vicente Creek include: [ADD THE MAP]
SCWK Site 1 – at Big Ditch Park,
SCWK Site 2 – at the Hudson Street Bridge,
SCWK Site 3 – below the old smelter (Silver City Reduction Works) and,
SCWK Site 4 – near the old landfill (established after, but upstream of Site 3)

We established one site on Pinos Altos Creek in 2023:
PA Site 1 – at the Silver City Disc Golf Course (Hearst Mill site)

SCWK Site 1

SCWK Site 1 is the uppermost monitoring location and is located about 300 yards downstream of the confluence of Silva Creek and Pinos Altos Creek. It represents the deeply incised channel (Big Ditch) in the old flood plain where Main Street was laid out then subsequently cut 30-40 ft over a period of 30-40 years beginning in the mid 1870s. The perennial reach is maintained from up-gradient shallow groundwater sources meeting a more impermeable body of igneous rock and flowing over it. Base or low flow is usually about 0.5 cubic feet per second (cfs) and water quality parameters at this site are generally more characteristic of groundwater with frequent low dissolved oxygen readings which may account for the lack of fish at this location. The public can easily access the inner channel of the Big Ditch at this location so that state standards for partial to full body immersion (secondary and primary contact designated uses) are applicable.

SCWK Site 2

SCWK Site 2 is located just east of the Hudson Street Bridge about 800 yards downstream of Site 1. It represents the end of the deeply incised flood plain and usually exhibits the best base flow water quality. In a 2002 water quality survey, the NM Environment Department Surface Water Quality Bureau shocked and counted hundreds of long-fin dace, a native, small minnow-like fish. Thus a viable warm water fishery exists through this reach from several hundred yards upstream of the site and downstream past the next monitoring location. The gradient at this site is steeper, dissolved oxygen is generally high, and base flow rises to about 1 cfs.

SCWK Site 3

SCWK Site 3 was established near the end of the base flow perennial section of San Vicente Creek and just downstream of the old smelter and an adjacent pile of mill tailings. It is a “losing reach” (a stream that loses water as it flows downstream. The water infiltrates into the ground recharging the local groundwater, because the water table is below the bottom of the stream channel) at base flow and will occasionally exhibit isolated pools with no connecting flow. It represents decreasing water quality due to decreasing flow. It also provides some opportunity to monitor the effect from storm water runoff from the tailing/smelter site and the Agave Arroyo drainage. The mill tailings were targeted by SCWK for cleanup and were reclaimed with funds from the NM Office of the Natural Resources Trustees.

SCWK Site 4

SCWK Site 4 (at “The Jungle”) is about 400 yards downstream of Site 2 and about 600 yards upstream of Site 3. It represents the lower gradient perennial section supporting the San Vicente Creek fishery.

PA Site 1

Quarterly measurements are taken at these sites, including pH, dissolved oxygen, temperature, turbidity, total dissolved solids, electrical conductivity, and bacteria (E. coli). Comparing the data to New Mexico surface water quality standards allows us to identify any pollution sources in the waterway or potential stream impairments that need to be addressed. Monitoring results are submitted annually to the New Mexico Environment Department to track water quality trends in San Vicente Creek and to contribute to the state-wide water quality assessment.

Bacteria Monitoring

Regular monitoring for total coliforms and E. coli within the riparian zone helps us to identify potential waste entering the water. High E. coli concentrations pose an environmental health risk for people who come in contact with creek water. SCWK has worked with local officials to ensure that the public is made aware of the times when E.coli concentrations are high through signage and other communications methods. 

About the measurements:

• Temperature: At flood flows, temperature will usually drop rapidly even during the hottest days when intense summer thunderstorms dump large volumes of cold fresh runoff into the creek. Even small summer floods starting far upstream will cause water temperature to decrease from Site 1 through all the other sites. Snow melt, rain on snow, and cold winter rains can also influence temperature, but not as much as summer runoff.
• Dissolved Oxygen: A range of 5 to 9 parts per million (ppm) is considered a healthy dissolved oxygen level. The dissolved oxygen levels within our stream tend to be normal with fluctuations occurring due to temperature, flooding, and drought. Too exaggerated of fluctuations may make it difficult for aquatic and macroinvertebrate life to thrive year round.
• pH: A pH of seven (7) is considered neutral; a pH lower than 7 is acidic, and higher than 7 is basic. A normal range for surface water is 6.5 to 8.5. pH is especially important in San Vicente Creek, because a drop in pH
• E. coli:  SCWK monitoring of fecal coliforms and E. coli show fluctuation within San Vicente Creek at Site 1. Pet waste and sewage leaks are two contributors to an increase in E. coli in San Vicente Creek. While an increase in fecal coliform is predictable after a rain event, it can also happen at low flow.