An assessment of water quality and microbial risk in Rio Grande basin in the United States–Mexican border region

Increased reliance of urban populations on Rio Grande water has necessitated an expanded microbial surveillance of the river to help identify and evaluate sources of human pathogens, which could pose a public health risk. The objectives of this study were to investigate microbial and chemical water quality in Rio Grande water and to perform risk assessment analyses for Cryptosporidium. No oocysts in any of the ten-litre samples were detected. However, the limit of detection in the water samples ranged between 20 and 200 oocysts/100 L. The limits of detection obtained in this study would result in one to two orders of magnitude higher risk of infection for Cryptosporidium than the U.S.EPA annual acceptable risk level of 10−4. The bacterial data showed the significance of animal farming and raw sewage as sources of fecal pollution. Male specific and somatic coliphages were detected in 52% (11/21) and 62% (24/39) of the samples, respectively. Somatic coliphages were greater by one order of magnitude, and were better correlated with total (r2=0.6801; p≤0.05) and fecal coliform bacteria (r2=0.7366; p≤0.05) than male specific coliphages. The dissolved organic carbon (DOC) and specific ultraviolet absorbance (SUVA) values ranged 2.58–5.59 mg/L and 1.23–2.29 m−1 (mg/l)−1, respectively. Low SUVA values of raw water condition make it difficult to remove DOC during physical and chemical treatment processes. The microbial and chemical data provided from this study can help drinking water utilities to maintain balance between greater microbial inactivation and reduced disinfection by-products (DBPs) formation.

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The potential to improve water quality in the middle Rio Grande through effective wetland restoration

Water Science & Technology ◽

10.2166/wst.2010.323 ◽

2010 ◽

Vol 62 (3) ◽

pp. 501-509 ◽

Cited By ~ 6

Author(s):

Ruth Rodriguez ◽

Vanessa L. Lougheed

Keyword(s):

Water Quality ◽

El Paso ◽

Treatment Plant ◽

Rio Grande ◽

The United States ◽

Ciudad Juarez ◽

Irrigated Agriculture ◽

Nutrient Chemistry ◽

Mexico Border ◽

United States Mexico

The Rio Grande, which forms the United States—Mexico border for much of its course, receives diverse pollutants from both urban and agricultural areas, most notably in the sister cities of El Paso (TX, USA)—Ciudad Juárez (CHI, Mexico). This study aimed to describe regional trends in water quality in waters near the El Paso–Ciudad Juárez metroplex and to examine the potential for water quality improvement through the use of a created wetland. Very few differences in nutrient chemistry were found among drains, canals and the Rio Grande, with the exception of elevated chloride and lower phosphorus levels found in the drains. Overall, chloride concentrations increased with distance downstream, likely due to concentration of salts via evaporation from irrigated agriculture. A wastewater treatment plant (WWTP) contributed substantially to total phosphorus and nitrate levels, which, together with ammonia, tended to exceed state criteria for water quality downstream of the WWTP outflow. The created Rio Bosque wetlands reduced nitrate concentrations in the water, possibly via denitrification enhanced by algae; algae increased in biomass as water flowed through the wetlands. However, the diversion of water for irrigated agriculture, resulting in the absence of water, and thus aquatic plants, in the wetland in the summer has limited the ability of this wetland to improve regional water quality.

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Identification of microbial faecal sources in the New River in the United States–Mexican border region

Journal of Water and Health ◽

10.2166/wh.2009.025 ◽

2009 ◽

Vol 7 (2) ◽

pp. 267-275 ◽

Cited By ~ 5

Author(s):

Rezaur Rahman ◽

Absar Alum ◽

Hodon Ryu ◽

Morteza Abbaszadegan

Keyword(s):

Water Samples ◽

Sampling Site ◽

Environmental Water ◽

The United States ◽

Border Region ◽

Faecal Contamination ◽

Group Iii ◽

Group I ◽

International Boundary ◽

Male Specific

Water samples were analysed to differentiate human and animal faecal contamination of the New River, Mexico/USA, by genotyping bacterial viruses detected in the samples. From 46 water samples collected from the New River, 372 plaques of male-specific coliphages were isolated and genotyped; 44% of the plaques were identified as F-RNA coliphages and further characterized into four groups. Group I was the most prevalent (56%), followed by group IV (25%), group III (10%) and group II (9%). Group III coliphages were only detected at the sampling site in the vicinity of the international boundary, indicating human faecal contamination. As the New River traverses through the US region, groups I and IV coliphages were predominantly identified, but no human-specific genotypes were detected. The study also found that water temperature influenced the prevalence of the relative proportions of F-RNA coliphages in the environmental water samples. The strategy used in this study appears to be a practical and reliable tool for monitoring and distinguishing between human and animal faecal contamination.

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Transboundary Aquifers between Baja California, Sonora and Chihuahua, Mexico, and California, Arizona and New Mexico, United States: Identification and Categorization

Water ◽

10.3390/w13202878 ◽

2021 ◽

Vol 13 (20) ◽

pp. 2878

Author(s):

Rosario Sanchez ◽

Laura Rodriguez

Keyword(s):

United States ◽

Water Quality ◽

New Mexico ◽

Baja California ◽

The United States ◽

Border Region ◽

Aquifer Potential ◽

Transboundary Aquifers ◽

The U.S

In 2016, research suggested there might be up to 36 transboundary aquifers located along the border between Mexico and the U.S. The main contribution of this study was to put together the available segments already existent in the literature without considering the validity of the criteria used to define the boundaries of those segments. In 2018, updated research reported 33 hydrogeological units (HGUs) crossing the boundaries between Mexico and Texas. This later analysis included the homogenization of geological nomenclatures, standardization of geological and hydrogeological criteria, using a specific methodology to correlate, identify, and delineate each HGU. The purpose of this paper is to use this latter methodology and expand the same analysis to include the transboundary aquifers between Baja California/California, Sonora/Arizona, and Chihuahua/New Mexico. Results of this study indicate that a total of 39 HGUs have been identified in this region which accounts for an approximate shareable land of 135,000 km2 where both countries share half of the area. From the total shareable area, around 40% reports good to moderate aquifer potential and water quality, of which 65% is in the U.S. and 35% on the Mexico side. Border-wide, the total number of HGUs in the border region between Mexico and the United States is 72, covering an approximate area of 315,000 km2 (180,000 km2 on the U.S. side and 135,000 km2 on the Mexico side). The total area that reports good to moderate aquifer potential as well as good to regular water quality ranges between 50 and 55% (of which approximately 60% is in the U.S. and the rest in Mexico).

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