To quantify seepage losses from the Medina and Diversion Lake system that provide recharge to the Edwards aquifer and upper zone of the Trinity aquifer, water budgets were analyzed for the period during March 2, 1955–October 6, 2022, and over a range of stages in Medina Lake. In the water-budget analysis, the applicable components of the hydrologic cycle pertaining to Medina and Diversion Lakes were evaluated. The water-budget equation incorporates measurable terms of inflow and outflow to solve for (or otherwise scientifically estimate) unknown gains or losses, or both, from a lake or lake system. The measurable terms include precipitation, evaporation, surface water inflow and outflow, and change in lake storage. The solution to the water-budget equation is obtained by balancing the contribution of each term of the water budget for any given budget period. The net effect of the unknown gains and losses is represented by the residual of the measurable terms and is assumed to represent recharge to the Edwards aquifer and upper zone of the Trinity aquifer. This data set contains hydrologic data (precipitation, evaporation, streamflow, lake elevation, reservoir storage, and reservoir surface area) collected in the drainage area of Medina and Diversion Lake during 1955–2022. A file containing a list of sites where the data were collected is included. In 2017, a meteorological station was installed on the shore of Medina Lake to collect continuous precipitation and evaporation data; a file containing daily hydrologic data collected during 2017–22 is included, along with a file containing calculated daily water-budget values collected during 2017–22, and a file containing data from selected water-budget periods between 1955 and 2022.