Argentina is a developing Latin American nation that has an aim of achieving the United Nations Millennium Development Goals for potable water supplies. Their current regulations however, limit the continued development of improved potable water quality and infrastructure from a microbiological viewpoint. This is since the current regulations are focused solely to pathogenic Eschericia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and fecal indicators. Regions of lower socioeconomic status such as peri-urban areas are particularly at risk due to lessened financial and political ability to influence their environmental quality and infrastructure needs. Therefore, a combined microbiological sampling, analysis and quantitative microbial risk assessment (QMRA) modeling effort were engaged for a peri-urban area of Salta Argentina. Drinking water samples from home taps were analyzed and a QMRA model was developed, results of which were compared against a general 1:10,000 risk level for lack of a current Argentinian standard. This QMRA model was able to demonstrate that the current regulations were being achieved for E. coli but were less than acceptable for P. aeruginosa in some instances. Appropriate health protections are far from acceptable for Giardia for almost all water sources. Untreated water sources were sampled and analyzed then QMRA modeled as well, since a significant number of the community (∼9%) still use them for potable water supplies. For untreated water E. coli risks were near 1:10,000, however, P. aeruginosa and Giardia risks failed to be acceptable in almost all instances. The QMRA model and microbiological analyses demonstrate the need for improved regulatory efforts for the peri-urban area along with improved investment in their water infrastructure.

In a case study located in suburban sectors of the metropolitan area of the Lerma Valley (Valle de Lerma), in the province of Salta (Argentina), 24 informal decentralized wastewater treatment systems (DWWTS) were evaluated. The analyzed systems had three general configurations: A, septic tank; B, septic tank combined with upflow anaerobic sludge blanket (UASB) reactor; C, septic tank combined with UASB and a final filtration step. Statistically significant differences (p < 0.05) were observed in effluent quality, measured as total coliforms, thermotolerant coliforms, and chemical oxygen demand (COD). Treatment A was the most inefficient, and was statistically different from B and C; there were no significant differences between the latter two. Thermotolerant coliform concentrations were high in all analyzed systems and did not comply with local discharge standards in soakaway pits or in the ground. The lack of a final disinfection step in these systems is thus a weakness that needs to be addressed. The formal inclusion of DWWTS in urban planning could reduce overall investment costs, as long as the best technologies are selected for each case. Incorporation of DWWTS in formal urban planning requires an open debate in which the social perspectives of all relevant users need to be considered.

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Drinking water monitoring plans are important to characterize both treated and untreated water used for drinking purposes. Access to drinking water increased in recent years as a response to the Millennium Development Goals set for 2015. The new Sustainable Development Goals aim to ensure universal access to safe drinking water by 2030. Within the framework of these global goals, it is crucial to monitor local drinking water systems. In this paper, treated and untreated water from different sources currently consumed in a specific town in Salta, northern Argentina, was thoroughly assessed. Monitoring extended along several seasons and included the physical, chemical and microbiological variables recommended by the Argentine Food Code. On the one hand, treated water mostly complies with these standards, with some non-compliances detected during the rainy season. Untreated water, on the other hand, never meets microbiological standards and is unfit for human consumption. Monitoring seems essential to detect anomalies and help guarantee a constant provision of safe drinking water. New treatment plants are urgently needed to expand the water grid to the entire population.

The reservoirs of the upper Juramento basin (Cabra Corral and El Tunal) and the Salí-Dulce basin (El Cadillal, Río Hondo, and Escaba) show certain peculiarities due to their geographical location, basin morphology and limnological features. Such peculiaritieswere compared duringsignificant algal bloom periodsbetween 2002 and 2008, by analyzing the mainphysicochemical parameters and ecological attributes of the phytoplankton assemblagesusing standard methods. Tucumán reservoirs were different in most variables showing higher values of conductivity, nutrients and algal biomass.Regarding the hydrological cycle, El Cadillal exhibited the lowest biomass average (2.74 mg Chl.m-3) during maximum water flows, whereas the Cabra Corral lacustrine zone exhibited the highest biomass average (63.36 mg Chl.m-3) during minimum water flows. For the same period, the Cabra Corral lacustrine zone exhibited lower phytoplankton diversity and richness (1.37 and 9, respectively), in accordance with dinophyte blooms of Ceratium sp. In all reservoirs, the following biological variables showed a significant contrast in the hydrological cycle: highest phytoplankton biomass during minimum water flows (35.68 mg Chl-a m-3) vs. waterfloods (13.68 mg Chl-a m-3) (T = 3.42, P = 0.001). During minimum water flows, richness (14.30 sp.) and equitability (0.51) were lower vs. waterfloods (20.23, 0.59, respectively) (T = 2.36; P = 0.0196), as a result of the allochthonous nutrients provided by the main tributaries.Management of the reservoirs’hydrometric levels during dry season determines the deterioration of the waterquality with increased algal blooms. In order to ensure the systems’ sustainability, eutrophication must be controlledwithprograms to reduce diffuse nutrient loads and to treat residential and agroindustrial effluents, particularly in Sali-Dulce basin.

Las actividades mineras originan condiciones ambientales extremas en los sistemas acuáticos porque tienden a producir altas concentraciones de metales pesados debido a que su solubilidad se incrementa marcadamente con la disminución del pH. En la región andina de la provincia de Jujuy a 4,200 m snm, el sistema exorreico del río Orosmayo (Ajedrez) está afectado por la explotación de plata en la mina Pirquitas. Se evaluó la estructura y composición del fitoplancton en 5 tributarios mediante muestreos en otoño y primavera del periodo 2011-2013, empleando técnicas estándares. La abundancia del fitoplancton fue más alta en la estación lluviosa, especialmente en marzo de 2011, en todos los sitios, con un máximo de 828 ind.ml −1 en el río Ajedrez. Los datos fisicoquímicos revelan condiciones ácidas en el río Pircas (pH entre 2.6 y 3.9) con altas concentraciones de Al 3+ y Fe 3+ . Este sitio mostró menores valores de densidad de individuos (176 ind.ml −1 ), diversidad (2.67) y riqueza de especies (promedio 11) significativamente menores a los otros sitios de muestreo. Las diatomeas fueron afectadas por el pH en el río Pircas, siendo su representación baja (18.48%), con predominio de algas verdes (52%), principalmente fitoflagelados (Chlamydomonas, Dunaliella) y filamentos (Klebsormidium, Spirogyra, Zygogonium, Ulothrix), entre otras.

El embalse Limón se ha convertido en la principal fuente de agua potable para el 80% de la población del norte de la provincia de Salta (22° 05’47,90’’S-63° 44’ 19,48’’ W). Al presente, no existe información sistematizada de las algas del fitoplancton presentes en esta presa. Se analizaron 19 muestras del período 2013-2015 en ambas fases del ciclo hidrológico, según técnicas estandarizadas, con el objeto de evaluar la representatividad de cianobacterias potencialmente tóxicas en Limón y su importancia relativa en el fitoplancton. Existió un predominio de cianobacterias, con un incremento interanual significativo, siendo éstas más abundantes en los estiajes, con un promedio de 110.160 células en 2015, con predominio de Cylindrospermopsis raciborskii y Raphidiopsis mediterranea (75.027 y 170.000 células/ml). Entre las especies con potencial toxicogénico se destacaron por sus densidades Anabaenopsis elenkinii,  Aphanizomenon gracile, Aphanocapsa annulata, Coelomoron tropicale, Chroococcus dispersus, C. raciborskii, Microcysis flos-aquae, Planktolyngbia limnetica, Pseudanabaena limnetica, R. mediterránea y R. curvata. La representatividad del grupo dentro del fitoplancton fue superior al 70 %. Se concluye que el cuerpo de agua es un ambiente de riesgo y debe ser monitoreado permanentemente para su empleo para agua de consumo humano.

The water quality of rivers belonging to an arid sub‐basin in northern Argentina was evaluated in a longitudinal gradient, during the period of maximum dryness in 2017. The composition and structure of the phytobenthos were studied using biotic indices. A total of 126 spp. were determined, with a predominance of diatoms and Cyanobacteria. Most of the diatom species found were meso to polyhalobus and tolerant to organic contamination. Despite the rivers of the basin cross areas with very different land uses, no differences were recorded in phytobenthos abundances between sites. The Pantle & Buck Saprobity index classified the sub‐basin in the α‐mesosaprobability range, and the diatomaceous eutrophication/pollution index assigns poor quality to most of the sites. Salinity should induce phycoflora homogenization that limits the sensibility of biotic indices to anthropogenic impacts.