Last updated: August 26, 2025
Article
Climate and Water Monitoring at Lyndon B. Johnson National Historical Park: Water Year 2024
NPS/CYNTHIA DORMINEY
Overview
Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid ecosystems (Woodhouse and Overpeck 1998). Understanding changes in climate, groundwater, and surface water is key to assessing the condition of park natural resources—and often, cultural resources.
At Lyndon B. Johnson National Historical Park (Figure 1), Southern Plains Inventory and Monitoring Network scientists study how ecosystems may be changing by taking measurements of key resources, or “vital signs,” year after year—much as a doctor keeps track of a patient’s vital signs. This long-term ecological monitoring provides early warning of potential problems, allowing managers to mitigate them before they become worse. At Lyndon B. Johnson National Historical Park, we monitor climate and groundwater, among other vital signs.
Groundwater conditions are closely related to climate conditions. Because they are better understood together, we report on climate in conjunction with water resources. Reporting is by water year (WY), which begins in October of the previous calendar year and goes through September of the water year (e.g., WY2024 runs from October 2023 through September 2024). This web report presents the results of climate and groundwater monitoring at Lyndon B. Johnson National Historical Park (Figure 1) in WY2024.
Reference: Woodhouse, C. A., and J. T. Overpeck. 1998. 2000 years of drought variability in the central United States. Bulletin of the American Meteorological Society 79(12): 2693–2714. https://doi.org/10.1175/1520-0477(1998)079%3C2693:YODVIT%3E2.0.CO;2
NPS
Climate and Weather
There is often confusion over the terms “weather” and “climate.” In short, weather describes instantaneous meteorological conditions (e.g., it’s currently raining or snowing, it’s a hot or frigid day), and climate reflects patterns of weather at a given place over longer periods of time (seasons to years). Climate is the primary driver of ecological processes on earth. Climate and weather information provide context for understanding the status or condition of other park resources.
Methods
A National Oceanic and Atmospheric Administration Cooperative Observer Program (NOAA COOP) weather station (Johnson City 2N #414605) has been operational near Lyndon B. Johnson National Historical Park since 1964 (Figure 1). This station typically provides a reliable climate dataset. However, in WY2024 it was missing data on 53 days. As a substitute, climate analyses in this year’s report use WY2024 and 30-year averages (1991–2020) of gridded surface meteorological (GRIDMET) data from the location of the park visitor center. Subsequent reports may revert to the NOAA weather station as the data source, depending on future data quality.
GRIDMET is a spatial climate dataset (4-kilometer resolution) that is interpolated using weather station data, topography, and other observational and modeled land surface data. Temperature and precipitation estimated from GRIDMET may vary from actual weather at a particular location depending on the availability of weather station data and the difference in elevation between the location of interest and that assigned to a grid cell. Data from both weather station and GRIDMET are accessible through Climate Analyzer.
NPS
Results
Precipitation
Annual precipitation at Lyndon B. Johnson National Historical Park in WY2024 was 32.88″ (83.5 cm), 0.61″ (1.5 cm) more than the 1991–2020 annual average. While annual precipitation was similar to the 30-year average, monthly precipitation totals in six months of the year showed substantially more departures from average (Figure 2). October, May, and July were wetter than average by 26–138%. November, August, and September were drier than average by 32–71%. Precipitation during the other six months was similar to the respective monthly averages.
Air Temperature
The mean annual maximum temperature at Lyndon B. Johnson National Historical Park in WY2024 was 79.0°F (26.1°C), 0.4°F (0.2°C) above the 1991–2020 average. The mean annual minimum temperature in WY2024 was 56.4°F (13.6°C), 2.3°F (1.3°C) above the 1991–2020 average. Mean monthly maximum and minimum temperatures in WY2024 differed by as much as 5.7°F (3.2°C; see February as an example) relative to the 1991–2020 monthly averages (Figure 2). Mean monthly maximum temperatures were above average in every month except November, January, and July. Mean monthly minimum temperatures were above average in every month except January.
NPS
Drought
Reconnaissance drought index (Tsakiris and Vangelis 2005) provides a measure of drought severity and extent relative to the long-term climate. It is based on the ratio of average precipitation to average potential evapotranspiration (the amount of water loss that would occur from evaporation and plant transpiration if the water supply was unlimited) over short periods of time (seasons to years). The reconnaissance drought index for Lyndon B. Johnson National Historical Park indicates that WY2024 was slightly wetter than the 1991–2024 average from the perspective of both precipitation and potential evapotranspiration (Figure 3).
Reference: Tsakiris G., and H. Vangelis. 2005. Establishing a drought index incorporating evapotranspiration. European Water 9: 3–11.
NPS
NPS
Groundwater
Groundwater is one of the most critical natural resources of the Southern Plains and American Southwest. It provides drinking water, irrigates crops, and sustains rivers, streams, and springs throughout the region.
Methods
Lyndon B. Johnson National Historical Park groundwater is monitored at two wells outside the park boundary (Figure 1) by the Texas Water Development Board (TWDB). Well 57-51-317 is 1.0 miles (1.61 km) west of the LBJ Ranch District and is monitored twice a year. Well 57-45-822 is adjacent to the western edge of the Johnson City District and was monitored manually through WY2022. Daily monitoring using automated methods started in November 2022. Data are available at the
TWDB Database.
Results
Average depth to water at well 57-45-822 in WY2024 was 58.89 feet below ground surface (ft bgs; 17.95 m bgs), slightly higher than the previous year (Table 1). Water levels were lowest at the start of the water year, then increased through the cool season, and leveled off in late March. Average depth to water at well 57-51-317 in WY2024 was 30.10 ft bgs (9.17 m bgs), slightly lower than the previous water year.
Well 57-45-822 shows substantial seasonal variation, likely in response to precipitation and associated shallow recharge (Figure 4). Well 57-51-317 does not exhibit high inter-year variability, likely because it is situated 500 ft (152 m) from the Pedernales River. The monitoring data indicate that the water level in both wells is declining over their respective periods of record.
Table 1. Groundwater monitoring results in water year (WY) 2024, Lyndon B. Johnson National Historical Park (amsl = above mean sea level; bgs = below ground surface).
| State Well Number | Location | Wellhead Elevation (ft) |
Depth to Water (ft bgs) |
Water Level Elevation (ft amsl) |
Change in Elevation from WY2024 (± ft) |
Change in Elevation from Earliest Recorded Water Level (± ft and year of first record) |
|---|---|---|---|---|---|---|
| 57-45-822 | 14 ft west of the Johnson City District | 1,233.00 | 58.89 | 1,174.11 | +0.20 | −23.37 (2004) |
| 57-51-317 | 1 mile west of LBJ Ranch District | 1,447.00 | 30.10 | 1,416.9 | −0.15 | −3.65 (2016) |
NPS
Report Citation
Authors: Kara Raymond, Andy Ray
Raymond, K., and A. Ray. 2025. Climate and Water Monitoring at Lyndon B. Johnson National Historical Park: Water Year 2024. Southern Plains Network, National Park Service, Pecos, New Mexico.