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Productive activities such as agriculture and livestock have transformed the Andean basins in South America. In accordance with this statement, the objective of this study was to assess the water quality of "Las Piedras" river located in an Andean basin with 6626 ha in Colombian Highlands. This study analyzed nutrient inputs from agricultural production, spatial crops distribution, human activities and their influence on the ecological state of the river. The evaluation integrated physicochemical and biological parameters in the indexes of water quality, pollution and the aquatic macroinvertebrates community. Results showed that aggregated crop fields occupy 25.2 % in the basin and the biological water quality through the Biological Monitoring Working Party (BMWP) index denotes the presence of tolerant-pollution organisms, additionally the biodiversity was low (Shannon H´1.1). The water quality in the river satisfies the Colombian regulation criteria for human consumption, even higher concentrations of nutrients in the lower area with 2.20 mg/L nitrates and 1.49 mg/L of phosphates, besides the loss of nutrients by runoff, which was 2.57 mg/L nitrates in the middle area and 0.18 mg/L phosphates in the upper area. In this sense, the nutrient concentration input increases toward the lower area of the basin because of the crop distribution. The agricultural land use modified the hydrological ecosystem services by decreasing the basin water regulatory capacity and nutrients input to the main stream.Palabras clave: contaminación hídrica, agricultura, distribución espacial de los cultivos, biodiversidad, agua potable RESUMENLas actividades productivas como la agricultura y la ganadería han transformado las cuencas andinas de América del Sur. El objetivo de este estudio fue evaluar la calidad del agua en la cuenca del río Las Piedras (6626 ha), localizada en la alta montaña colombiana. Se analizaron los aportes de nutrientes a partir de la producción agrícola, distribución espacial de cultivos, actividades humanas y su influencia en el estado ecológico del río. La evaluación integró los parámetros físicos, químicos y biológicos en índices de calidad del agua, de contaminación y de macroinvertebrados acuáticos. Los resultados mostraron que los cultivos ocupan el 25.2 % de la cuenca, la calidad biológica del agua según el 362índice del Grupo de Trabajo de Monitoreo Biológico (BMWP, por sus siglas en inglés) evidenció la presencia de organismos tolerantes a la contaminación y baja biodiversidad (Shannon H' 1.1). La calidad del agua es apta para consumo humano según los estándares establecidos por la normatividad Colombiana. Sin embargo, se encontraron altas concentraciones de nutrientes en la zona baja del río con 2.20 mg/L de nitratos y 1.49 mg/L de fosfatos, adicionalmente los aportes de nutrientes en escorrentía superficial fueron de 2.57 mg/L de nitratos en la zona media y 0.18 mg/L de fosfatos en la zona alta. En este sentido, se observó que el ingreso de nutrientes aumenta hacia la zona baja de la cuenca deb...

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Climate change is exacerbating drought and water stress in several global regions, including some parts of the United States. During times of drought in the U.S., municipal governments, private water suppliers and non-profits commonly deploy advocacy campaigns and incentive programs targeting reductions in residential water use through actions including: repairing leaks, shutting off taps, and installing new water-saving appliances. We asked whether these campaigns have the potential to alleviate water stress during drought at the county scale by estimating the potential impact of full adoption of such actions. In 2010, we show that the maximum potential use reductions from these residential actions may only alleviate water stress in 6% (174) of U.S. counties. The potential impact of domestic programs is limited by the relative dominance of agriculture water withdrawal, the primary water user in 50% of U.S. counties. While residential actions do achieve some water demand savings, they are not sufficient to alter water stress in the majority of the continental U.S. We recommend redirecting advocacy efforts and incentives to individual behaviors that can influence agricultural water use.

Land-use decision making in densely populated cities is challenged to cover the urban demand for water and food while maintaining the integrity of ecosystems that regulate the supply of these ecosystem services, beyond urban limits. Land-use decision making can be informed using spatial analysis of ecosystem services supply and demand, shedding light on potential mismatches, surpluses, deficits, and unsustainable uses of ecosystems. The integration of such analysis in land-use decision making, however, can be challenged by the complexity of the hierarchical and inflexible planning models used in various countries. We explored how the analysis of potential mismatches, surpluses, and deficits in the supply and demand of water and fertile soil can be spatially assessed for urban areas, and how such information can be used to inform land-use decision making. We used official data and geoprocessing methods to map water -supply, demand, and risk for water scarcity-, and fertile supply –supply, demand, and risk for food insecurity-, for Bogota and Villavicencio. We showed a high risk for water scarcity in Bogota, and an increasing competition for fertile soil between urbanization and agriculture. We recommended a cooperative management strategy of ecosystems and services considering that both cities shared river basins and natural reserves, in addition to their strike differences in population size. Inter-jurisdictional and inter-municipal cooperation, in addition to strong governance, are necessary to handle mismatches of urban ecosystem services supply and demand, and a potential solution to solve conflicts related to access, availability, and jurisdiction of ecosystem services in urban areas..