Evaporation data from Lake Mead, Nevada and Arizona, 2021-2023

This U.S. Geological Survey data release presents monthly evaporation estimates from Lake Mead, Nevada and Arizona, for January 2021 through December 2023.

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 from 30-minute time series. Daily and 30-minute values are archived in the National Water Information System under USGS site number 360500114465601. Monthly values are marked as estimated when a significant portion of daily values are estimated. Gaps in the latent heat, sensible heat, and air temperature time series were filled through linear interpolation for small gaps (up to a few hours) or by using the mean daily value of each time step for large gaps. Mean daily value is calculated from the average value of each time step from 7 days before the gap to 7 days after the gap.
(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 (Qx) was calculated based on methods in Earp and Moreo (2021). Net advection (Qn) was calculated based on data estimated by the Bureau of Reclamation 24-Month Study Most Probable report, accessed Dec 2025.
(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).
 
Continuous data (for all parameters) and daily, monthly, and annual measured data statistics (for all parameters except evaporation) for USGS site 360500114465601 can be found at the following sites:
https://waterdata.usgs.gov/monitoring-location/360500114465601
https://nwis.waterdata.usgs.gov/nv/nwis/dv/?site_no=360500114465601&age…
References Cited:
Bureau of Reclamation, Lower Colorado Region website: Operation Plan for Colorado River System Reservoirs (24-Month Study), accessed September 1, 2025 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://doi.org/10.3133/sir20135229.