Restoring the Water Quality of the San Pedro River Watershed
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RESTORING THE WATER QUALITY OF THE SAN PEDRO RIVER WATERSHED Item Type text; Proceedings Authors Klotz, Jason; Tecle, Aregai Publisher Arizona-Nevada Academy of Science Journal Hydrology and Water Resources in Arizona and the Southwest Rights Copyright ©, where appropriate, is held by the author. Download date 26/09/2021 19:34:08 Link to Item http://hdl.handle.net/10150/621703 RESTORING THE WATER QUALITY OF THE SAN PEDRO RIVER WATERSHED Jason Klotz1 and Aregai Tecle1 INTRODUCTION of public land that stretches from the Mexican border This paper is concerned with restoring the north to the town of St. David. The study area in this quality of water in some portions of the San Pedro paper begins just north of the River's confluence River. There are high concentrations of bacteria in with the Babocamari River and ends just south of some parts of the San Pedro River. Our aim is to Dragoon Wash (Fig. 1). The headwater parts of the find ways of improving the situation. Specifically, rivers and washes in the study area are either there are two objectives in the study. The first one ephemeral or intermittent streams. attempts to identify the possible sources of the bacterial contamination and assess its trends within WATER QUALITY IN THE STUDY AREA the watershed. The second objective is to determine Human beings and other warm-blooded animals appropriate methods of restoring the water quality. take in many different types of bacterial contamina- The main water quality problem is nonpoint source tion into their digestive tracts. Many types of pollution, which enters the stream and moves along bacteria are pathogenic and can be very harmful to with it. The magnitude of the problem is affected by humans and other animals. One of the main sources the size and duration of the streamflow, which of such bacteria is contaminated (or polluted) water. brings bacteria-laden sediment. The amount of sedi- A common way of determining the contamination ment brought into the system is large during the of water by bacteria is using an indicator bacteria, monsoonal events. At this time, the streamflow Escherichia coli or E. coli. This is a gram-negative becomes highly turbid in response to the organic and rod-shaped member of the genus Escherichia and inorganic sediments entering the system. Based that is commonly found in the lower intestine of on research done for this paper, the amount of warm-blooded animals such as humans. It is mostly bacterial concentration is strongly related to turbid- harmless, though some strains could be harmful and ity. Best management practices (BMPs) have been even deadly. Because they are commonly found in designed and implemented to restore the water qual- the intestines they are used as indicator species for ity problem in the area. The BMP's consist of the various types of bacteria that enter the digestive actions such as monitoring, educational outreach, systems of both humans and other warm-blooded proper signage, and other range/watershed related animals. The bacteria enter the body of animals and improvement practices. Other issues that contribute humans by coming into direct or indirect contact to the increasing amount of bacteria that are briefly with the feces of infected animals or humans. addressed in this paper are bank and gully erosion, Humans can also acquire bacteria from the con- flood control, and surface water and streamflow sumption of food or water that has been directly or issues that occur on the stream headwaters. indirectly contaminated by feces or other bodily excretions. STUDY SITE In 1972, the Federal Water Pollution Control The San Pedro River starts in the mountains Act of 1948 became amended as the Clean Water near Cananea in Sonora, Mexico and flows north- Act (USEPA 2015). This law made it unlawful to ward. It enters the United States in southeastern discharge point source pollutants into navigable Arizona and joins the Gila River near the town of waterways, unless a permit was obtained. In the Winkelman, Arizona. The river flows along the val- process, the law created standards for the safe ley between the Huachuca Mountains to the west amount of bacteria in freshwater lakes, streams, and and the Mule Mountains to the east. The annual rivers to help protect people from getting infected average precipitation over the area ranges between or becoming sick when using contaminated waters 14 inches (35.56 cm) and 30 inches (76.20 cm), for drinking and/or recreational purposes such as most of which comes as monsoon rains during July fishing, boating or swimming. In the state of through September. Streamflow in the river is low- Arizona, the standard level of bacterial contamina- est during the months of April through June, coin- tion for full body contact (FBC), such as swimming, ciding with the leafing of the vegetation. is no more than 235 colony forming units (CFU) per Within the San Pedro River basin is a conserva- 100 ml. The standard for partial body contact, such tion area known as the San Pedro Riparian National as boating and fishing, is no more than 576 Conservation Area (SPRNCA). This specially desig- cfu/100ml (USEPA 2003). The presence of the nated area covers roughly 57,000 acres (23,067.1 ha) indicator bacteria E. coli in the San Pedro River is 1School of Forestry, Northern Arizona University, Flagstaff, AZ. 14 Figure 1. Study area of the San Pedro Watershed. an indication of the presence of pathogenic organ- Nonpoint source pollution, on the other hand, is not isms that under full body contact or partial body defined under the Clean Water Act, but it is widely contact may enter into the body and become a health understood to be a type of pollution that arises from risk. In 2006, according to the Arizona Department dispersed activities that occur over large areas and of Environmental Quality, there were bacterial is not traceable to any single source. concentrations that surpassed the Arizona Water Quality Standard for full body contact (ADEQ Point Source Pollution 2010) in the San Pedro. This was determined by The main culprits for point source pollution in collecting various samples from sites along the river the study area are the four active Arizona Pollutant between Dragoon Wash and the mouth of the Discharge Elimination System (AZPDES) permits. Babocomari River (Fig. 1), and analyzing the These permits fall under the Environmental Protec- samples following commonly used protocols tion Agencies (EPA) National Pollutant Discharge (Stoeckel et al. 2004). Elimination System which controls point source discharges (USEPA 2015). These permits, acquired SOURCE OF POLLUTANTS by wastewater treatment plants in Tombstone, In general, water-quality problems may origi- Mammoth, Cielo and other nearby areas, authorize nate from both point and nonpoint sources. Accord- the discharge of treated wastewater into the ephem- ing to the Clean Water Act, “point source” pollution eral wash tributaries off the San Pedro River. For can be defined as example, the Sierra Vista Water Reclamation Facil- “any discernable, confined and discrete ity was allowed to start making emergency dis- conveyance type, including but not limited charges into the San Pedro River when it started to any pipe, ditch, channel, tunnel, conduit, operating in late 2014. Consequently, the reclama- well, discrete fissure, container, concen- tion facility is allowed higher permit limits in line trated animal feeding operation, or vessel with Arizona’s bacterial water-quality standard for or other floating craft from which pollut- ephemeral waters (ADEQ 2013). Another important ants are or may be discharged.” (Coronado permit, the Arizona Department of Transportation’s Resource Conservation & Development statewide Municipal Separate Storm Sewer System, 2013). falls under the statewide stormwater management plan. This permit includes all stormwater discharges 15 associated with construction sites, industrial facilities, in these arid and semi-arid regions, and the chances etc. It just happens that there is an Arizona highway of flash flooding in gullies and other drainages that covered by the permit which exists upstream of the feed into the San Pedro River increase as a result of San Pedro-Gila River confluence. This can be an the intense, short-lived monsoonal events that occur important source of bacteria and other contaminants throughout the region. Overland flow and flash- that enter the river. flood events have the potential to carry fecal Other important permits are the Multi-Sector material from livestock, and other domestic animals General Permit and the Construction General Per- into the river (Kress and Gifford 1984, Coronado mit. The common purpose of these two permits is to Resource Conservation & Development 2013). protect the quality and beneficial uses of Arizona's Many agriculture facilities in the area are allowed surface water resources from pollutants that come to directly apply manure to their allotments. Hence, from stormwater runoff produced by industrial and the irrigational conditions and stormwater runoff construction activities. As stated in the Clean Water become major sources of the nonpoint source pollu- Act, it is technically illegal to have a point source tion in the area (ADEQ 2013). The issue can be discharge of pollutants enter into the waters of the exacerbated when not managed properly. Livestock US, unless authorized by a permit. This includes and other herbivores can overgraze an area remov- stormwater runoff produced by industrial and ing all shrubs and other vegetative cover and construction activity sites. Some of the permits leaving it bare. Trampling causes soil compaction backed by this protocol are very close to the towns leading to lower infiltration rates and increased of Benson, Sierra Vista, and Bisbee in southeastern overland flow. The increased runoff washes the Arizona (ADEQ 2013). The locations of these sites fecal material into the stream courses, resulting in are very close to urban areas where stormflow increased loads of bacterial contaminants.