In cooperation with the Bureau of Reclamation (Lower Colorado Region), the U.S. Geological Survey collected meteorological data from 4/22/2013 to 4/25/2017 at Lake Mead and 4/11/2013 to 9/30/2016 at Lake Mohave. Meteorological monitoring equipment were mounted to a floating platform located at each lake. The data presented in this data release includes 30-minute mean air temperature, relative humidity, wind speed and direction, water surface temperature, net radiation, and incoming solar radiation. Quality assurance consisted of (1) monthly site visits to inspect and clean sensors, (2) recalibrating each sensor as necessary according to manufacturer guidelines, and (3) manual and graphical analysis for out-of-range values and anomalous patterns. Net radiation data were corrected for sensitivity to wind speed (Campbell Scientific, Inc, 2016) and calibrated following the procedures outlined in Moreo and Swancar (2013, p. 7-10). Meteorological data were collected in support of ongoing evaporation research at both lakes.

This U.S. Geological Survey data release presents monthly evaporation estimates from Lake Mead, Nevada and Arizona. Data are updated approximately annually. The spreadsheet includes five worksheets: (1) Read_Me worksheet contains information relevant to understanding the data contained in the rest of the worksheets. (2) Monthly_EC_Met worksheet includes data measured at a land-based station (USGS site identification number 360500114465601) using primarily eddy covariance measurement methods: uncorrected evaporation, latent- and sensible-heat fluxes, net radiation, air temperature, wind speed, and relative humidity. Values are monthly averages computed by averaging daily values except as noted. Monthly values are marked as estimated when a significant portion of daily values are estimated. (3) Monthly_Energy-Budget_Data worksheet includes computed data used to correct measured evaporation for energy balance. Computed data include monthly values for change in stored heat, net advection, turbulent flux, available energy, energy balance ratio, energy balance closure, and Bowen ratio. Change in stored heat was calculated based on methods in Earp and Moreo (2021). Net advection was calculated based on data estimated by the Bureau of Reclamation 24-Month Study (2022). Values are monthly averages or computed from monthly averages. (4) Annual_Energy_Balance worksheet includes annual averages of the Monthly_Energy_Balance data and the annual average values for energy-balance corrected sensible and latent heat fluxes. Values are annual averages or computed from annual averages. (5) Monthly_Evaporation_Estimates worksheet includes measured evaporation, corrected (most probable) evaporation, and energy balance ratio (EBR) adjusted evaporation, in feet. Values are monthly averages or computed from monthly averages. Data were processed according to methods described in Moreo and Swancar (2013) and Earp and Moreo (2021). References Cited: Bureau of Reclamation, Lower Colorado Region website: Operation Plan for Colorado River System Reservoirs (24-Month Study), accessed September 1, 2022 at https://www.usbr.gov/lc/region/g4000/24mo/index.html. Earp, K.J., and Moreo, M.T., 2021, Evaporation from Lake Mead and Lake Mohave, Nevada and Arizona, 2010–2019: U.S. Geological Survey Open-File Report 2021–1022, 36 p., https://doi.org/10.3133/ofr20211022. Moreo, M.T., and Swancar, A., 2013, Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012: U.S. Geological Survey Scientific Investigations Report 2013–5229, 40 p., http://dx.doi.org/10.3133/sir20135229.

This U.S. Geological Survey data release presents monthly evaporation estimates from Lake Mead, Nevada and Arizona. Data are updated approximately annually. The spreadsheet includes five worksheets: (1) Read_Me worksheet contains information relevant to understanding the data contained in the rest of the worksheets. (2) Monthly_EC_Met worksheet includes data measured at a land-based station (USGS site identification number 360500114465601) using primarily eddy covariance measurement methods: uncorrected evaporation, latent- and sensible-heat fluxes, net radiation, air temperature, wind speed, and relative humidity. Values are monthly averages computed by averaging daily values except as noted. Monthly values are marked as estimated when a significant portion of daily values are estimated. (3) Monthly_Energy-Budget_Data worksheet includes computed data used to correct measured evaporation for energy balance. Computed data include monthly values for change in stored heat, net advection, turbulent flux, available energy, energy balance ratio, energy balance closure, and Bowen ratio. Change in stored heat was calculated based on methods in Earp and Moreo (2021). Net advection was calculated based on data estimated by the Bureau of Reclamation 24-Month Study (2022). Values are monthly averages or computed from monthly averages. (4) Annual_Energy_Balance worksheet includes annual averages of the Monthly_Energy_Balance data and the annual average values for energy-balance corrected sensible and latent heat fluxes. Values are annual averages or computed from annual averages. (5) Monthly_Evaporation_Estimates worksheet includes measured evaporation, corrected (most probable) evaporation, and energy balance ratio (EBR) adjusted evaporation, in feet. Values are monthly averages or computed from monthly averages. Data were processed according to methods described in Moreo and Swancar (2013) and Earp and Moreo (2021). References Cited: Bureau of Reclamation, Lower Colorado Region website: Operation Plan for Colorado River System Reservoirs (24-Month Study), accessed September 1, 2022 at https://www.usbr.gov/lc/region/g4000/24mo/index.html. Earp, K.J., and Moreo, M.T., 2021, Evaporation from Lake Mead and Lake Mohave, Nevada and Arizona, 2010–2019: U.S. Geological Survey Open-File Report 2021–1022, 36 p., https://doi.org/10.3133/ofr20211022. Moreo, M.T., and Swancar, A., 2013, Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012: U.S. Geological Survey Scientific Investigations Report 2013–5229, 40 p., http://dx.doi.org/10.3133/sir20135229.

Evaporation rates were measured at Lake Mead from March 2010 through February 2012 for phase 1 of an evaporation study (Moreo and Swancar, 2013). Phase 2 of the study (March 2012 through September 2017) continues evaporation measurements at Lake Mead and begins evaporation measurements at another lower Colorado River Basin reservoir, Lake Mohave. Eddy covariance is the primary measurement method. Data currently (10/6/2015) are being collected for the phase 2 study. This USGS data release represents tabular data in support of the evaporation study. The data release was produced in compliance with the new 'open data' requirements as way to make the scientific products associated with USGS research efforts and publications available to the public. The data release consists of 2 separate items: 1. Lake Mead evaporation data from March 2010 through April 2015 (Microsoft Excel workbook) 2. Lake Mohave evaporation data from May 2013 through April 2015 (Microsoft Excel workbook)

Lake Mohave is one of several multi-purpose reservoirs that have been constructed on the Colorado River. The lake was formed upon completion of the Davis Dam in 1953. No mapping of the floor of the lake had been conducted since completion of the Davis Dam. The U.S. Geological Survey, in cooperation with researchers from the University of Nevada Las Vegas, completed a geophysical survey of this lake in April 2002. The survey included collection of sidescan sonar imagery of nearly the entire lake floor, and high-resolution seismic-reflection profiles along widely spaced lines throughout the lake. The detailed mapping of the lake floor was used to determine the amount of sediment that had accumulated in the lake since impoundment, its distribution, and the processes of deposition.

The Bureau of Reclamation conducted a survey at Lake Mohave Reservoir in December 2022. Survey data were used to update reservoir topography and compute the present storage-elevation relationship of the reservoir as an area-capacity (ACAP) table. This item is the ACAP table. For additional details, please refer to the corresponding report: https://data.usbr.gov/catalog/8529/item/133882

Selected evapotranspiration data were collected from 7/5/2011 to 1/1/2017 at the Amargosa Desert Research Site (ADRS, https://nevada.usgs.gov/adrs/) in support of ongoing research to improve the understanding of hydrologic and contaminant-transport processes in arid environments. The data presented in this data release includes 30-minute and daily evapotranspiration and associated energy-balance fluxes, precipitation, soil water content, air and soil temperature, wind speed and direction, humidity, and photosynthetically active radiation. Data methods follow those described in Moreo and others (2017). This is the third in a series of three releases of evapotranspiration data, which has been measured continuously at the ADRS since 2002.

Lake Mohave is one of several multi-purpose reservoirs that have been constructed on the Colorado River. The lake was formed upon completion of the Davis Dam in 1953. No mapping of the floor of the lake had been conducted since completion of the Davis Dam. The U.S. Geological Survey, in cooperation with researchers from the University of Nevada Las Vegas, completed a geophysical survey of this lake in April 2002. The survey included collection of sidescan sonar imagery of nearly the entire lake floor, and high-resolution seismic-reflection profiles along widely spaced lines throughout the lake. The detailed mapping of the lake floor was used to determine the amount of sediment that had accumulated in the lake since impoundment, its distribution, and the processes of deposition.

Lake Mohave is one of several multi-purpose reservoirs that have been constructed on the Colorado River. The lake was formed upon completion of the Davis Dam in 1953. No mapping of the floor of the lake had been conducted since completion of the Davis Dam. The U.S. Geological Survey, in cooperation with researchers from the University of Nevada Las Vegas, completed a geophysical survey of this lake in April 2002. The survey included collection of sidescan sonar imagery of nearly the entire lake floor, and high-resolution seismic-reflection profiles along widely spaced lines throughout the lake. The detailed mapping of the lake floor was used to determine the amount of sediment that had accumulated in the lake since impoundment, its distribution, and the processes of deposition.

Lake Mohave is one of several multi-purpose reservoirs that have been constructed on the Colorado River. The lake was formed upon completion of the Davis Dam in 1953. No mapping of the floor of the lake had been conducted since completion of the Davis Dam. The U.S. Geological Survey, in cooperation with researchers from the University of Nevada Las Vegas, completed a geophysical survey of this lake in April 2002. The survey included collection of sidescan sonar imagery of nearly the entire lake floor, and high-resolution seismic-reflection profiles along widely spaced lines throughout the lake. The detailed mapping of the lake floor was used to determine the amount of sediment that had accumulated in the lake since impoundment, its distribution, and the processes of deposition.