Water security is a top concern for social well-being, and dramatic changes in the availability of freshwater have occurred as a result of human uses and landscape management. Elevated nutrient loading and perturbations to major ion composition have resulted from human activities and have degraded freshwater resources. This study addresses the emerging nature of streamwater quality in the 21st century through analysis of concentrations and trends in a wide variety of constituents in streams and rivers of the U.S. Concentrations of 15 water quality constituents including nutrients, major ions, sediment, and specific conductance were analyzed over the period 1982−2012 and a targeted trend analysis was performed from 1992 to 2012. Although environmental policy is geared toward addressing the longstanding problem of nutrient overenrichment, these efforts have had uneven success, with decreasing nutrient concentrations at urbanized sites and little to no change at agricultural sites. Additionally, freshwaters are being salinized rapidly in all human-dominated land use types. While efforts to control nutrients are ongoing, rapid salinity increases are ushering in a new set of poorly defined issues. Increasing salinity negatively affects biodiversity, mobilizes sediment-bound contaminants, and increases lead contamination of drinking water, but its effects are not well integrated into current paradigms of water management.
For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Oelsner, G.P., Sprague, L.A., Murphy, J.C., Zuellig, R.E., Johnson, H.M., Ryberg, K.R., Falcone, J.A., Stets, E.G., Vecchia, A.V., Riskin, M.L., De Cicco, L.A., Mills, T.J., and Farmer, W.H., 2017, Water-quality trends in the Nation's rivers and streams, 1972-2012-Data preparation, statistical methods, and trend results (ver. 2.0, October 2017): U.S. Geological Survey Scientific Investigations Report 2017-5006, 136 p., https://doi.org/10.3133/sir20175006. ISSN 2328-0328 (online) iii ForewordSustaining the quality of the Nation's water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term economic, social, and environmental benefits that make a difference to the lives of the almost 400 million people projected to live in the United States by 2050. (http://water.usgs. gov/nawqa/applications/).In 1991, Congress established the National Water-Quality Assessment (NAWQA) to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. Since then, NAWQA has been a leading source of scientific data and knowledge used by national, regional, State, and local agencies to develop science-based policies and management strategies to improve and protect water resources used for drinking water, recreation, irrigation, energy development, and ecosystem needs. Plans for the third decade of NAWQA (2013-23) address priority water-quality issues and science needs identified by NAWQA stakeholders, such as the Advisory Committee on Water Information, and the National Research Council as the Nation faces increasing challenges related to population growth, increasing needs for clean water, and changing land-use and weather patterns.Federal, State, and local agencies have invested billions of dollars to reduce the amount of pollution entering rivers and streams that millions of Americans rely on for drinking water, recreation, and irrigation. Tracking changes in the quality of these waterways over multiple decades is crucial for evaluating the effectiveness of p...
A comprehensive hydro-ecological investigation was conducted to determine the ecological response of increased groundwater withdrawals from the Kirkwood-Cohansey aquifer system, an important source of water supply in southern New Jersey, USA. Collocated observations were made of aquatic-macroinvertebrate assemblages and stream hydrologic attributes to develop flow-ecology response relations. A sub-regional transient groundwater flow model (MODFLOW) was used to simulate three plausible high-stress groundwater-withdrawal scenarios which resulted in stream baseflow reductions of approximately 0.12, 0.20, and 0.26 m 3 s -1 . These reduction scenarios were used to construct flow-alteration ecological response models to evaluate aquaticmacroinvertebrate response to streamflow reduction. For example, flow-alteration ecological response models indicate that if groundwater withdrawals diminish mean annual streamflow from 1.1 to 0.6 m 3 s -1 , the abundance of intolerant taxa could be reduced by as much as 20%. These flow-alteration ecological response modelling results could be used by resource professionals to evaluate alternative water management strategies to determine maximum basin withdrawal rates that meet ongoing human water demand while protecting biological integrity.Key words hydro-ecology; streamflow alteration; aquatic macroinvertebrates; flow-ecology relations; groundwater model; MODFLOW; withdrawal scenarios Effets de la réduction des débits sur les macro-invertébrés aquatiques: relier les prélèvements d'eaux souterraines et la réponse des communautés dans les cours d'eaux du Sud du New Jersey, Etats-Unis Résumé Une enquête hydro-écologique globale a été menée pour déterminer la réponse écologique de l'augmentation des prélèvements d'eau souterraine de l'aquifère Kirkwood-Cohansey, une importante source d'approvisionnement en eau du Sud du New Jersey, Etats-Unis. Des observations co-localisées de communautés de macro-invertébrés aquatiques et d'attributs hydrologiques des cours d'eau ont été réalisées pour établir les relations de la réponse débit-écologie. Un modèle sous-régional transitoire de l'écoulement des eaux souterraines (MODFLOW) a été utilisé pour simuler trois scénarios plausibles de prélèvements importants des eaux souterraines qui ont abouti à une réduction du débit de base des cours d'eau de l'ordre de 0,12, 0,20 et 0,26 m3/s. Ces scénarios de réduction ont été utilisés pour élaborer des modèles de réponse écologique à l'altération du débit, pour évaluer la réponse des macro-invertébrés aquatiques à la réduction des débits. Par exemple, les modèles de réponse écologique à l'altération du débit indiquent que si les prélèvements d'eaux souterraines provoquent la diminution de l'écoulement annuel moyen de 1,1 m3/s à 0,6 m3/s, l'abondance des taxons intolérants pourrait être réduite de près de 20%. Ces résultats de la modélisation de la réponse écologique pourraient être utilisés par les professionnels des ressources pour évaluer des stratégies alternatives de gestion de l'eau afin de dé...
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