Climate and Water Monitoring at Lake Meredith National Recreation Area: Water Year 2023

Lake Meredith National Recreation Area, Texas.

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Overview

Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid ecosystems and across the Southern Plains (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 Lake Meredith National Recreation Area (Figure 1), Southern Plains 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 Lake Meredith National Recreation Area, we monitor climate, lake level, and groundwater, among other vital signs.

Surface water and 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., WY2023 runs from October 2022 through September 2023). This article reports the results of climate and water monitoring at Lake Meredith National Recreation Area (Figure 1) in WY2023.

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

Figure 1. Monitored weather station, lake level gage, and groundwater well at Lake Meredith National Recreation Area in WY2023.

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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). 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 (Sanford Dam #418040) has been operational at Lake Meredith National Recreation Area since 1993 (Figure 1). The long-term averages used for comparison in this report are from NOAA and are based on the period of record, 1993–2020. This station provides a reliable, climate dataset used for analyses in this report. Data from this station are accessible through Climate Analyzer.

Lake Meredith National Recreation Area

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Results for Water Year 2023

Precipitation

Annual precipitation at Lake Meredith NRA in WY2023 was 23.23″ (59.0 cm; Figure 2), 4.01″ (10.2 cm) more than the long-term annual average. This annual surplus primarily came in May and June, which received 5.09″ (12.9 cm) and 2.23″ (5.7 cm) more than the long-term averages, respectively. December, January, March, and August were substantially drier than average; the remaining months were slightly wetter than average. Extreme daily rainfall events (≥ 1″; 2.54 cm) occurred on 5 days and matched the average annual frequency of 4.8 days. Extreme rainfall events occurred on 26 April 2023 (1.96″; 5.0 cm), 04 May 2023 (1.37″; 3.5 cm), 19 May 2023 (1.62″; 4.1 cm), 01 June 2023 (1.60″; 4.1 cm), and 16 September 2023 (1.02″; 2.6 cm).

Air Temperature

The mean annual maximum temperature at Lake Meredith National Recreation Area in WY2023 was 74.2°F (23.4°C), only 0.1°F (0.1°C) above the long-term average. The mean annual minimum temperature in WY2023 was 43.7°F (6.5°C), 1.1°F (0.6°C) above the long-term average. Mean monthly maximum and minimum temperatures in WY2023 differed by as much as 6.3°F (3.5°C; see November as an example) relative to the long-term monthly averages (Figure 2). Mean monthly maximum and minimum temperatures were variable relative to the long-term averages throughout the year. Substantially cooler than average temperatures occurred in November and June, while substantially warmer than average temperatures occurred in January, August, and September. Extremely hot temperatures (≥ 100°F; 37.8°C) occurred on 43 days in WY2023, nearly double the average frequency of 24.7 days. Extremely cold temperatures (≤ 18°F; −7.8°C) occurred on 32 days, nearly double the average frequency of 18.6 days.

Figure 2. Climogram showing monthly precipitation and mean maximum and minimum temperature in water year 2023 and the long-term averages (which are based on the period of record, 1993–2020) at Lake Meredith National Recreation Area. Data source: climateanalyzer.org.

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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 Lake Meredith National Recreation Area indicates that WY2023 was wetter than the WY1994–2023 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.

Figure 3. Reconnaissance drought index for Sanford Dam station at Lake Meredith National Recreation Area, water years 1994–2023. Drought index calculations are relative to the time period selected (1993–2023). Choosing a different set of start/end points may produce different results. “N/A” = insufficient data to generate reliable estimates. Data source: climateanalyzer.org.

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Lake Level

Lake Meredith was formed by the construction of Sanford Dam between 1962 and 1965. Lake surface water level is not a Southern Plains Network vital sign; however, it is included in this report because the lake level has implications for park resources throughout Lake Meredith National Recreation Area.

Methods

The United States Geological Survey (USGS) has operated a water level gage at Lake Meredith (USGS 07227900 Lk Meredith nr Sanford, TX) since 1986. The gage is located at the downstream end of the lake at Sanford Dam. Every 15 minutes, the gage collects lake water level data. These data are available from the USGS.

Crane at Harbor Bay, Lake Meredith

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Recent Findings 

Mean lake level in WY2023 was 2,885.23 feet (879.42 m) above mean sea level (amsl) with a range of 12.49 ft (3.8 m) throughout the year (Figure 4). Lake level in WY2023 remained above the WY2001–2020 average lake level and the dead pool elevation (2,850.00 ft amsl or 868.68 m amsl) for the entire year. The dead pool elevation is the water level below which lake water cannot be drained by gravity to the downstream river. Near the end of WY2023, lake level approached, but did not surpass, the 2001–2020 maximum lake level.

For the entire monitoring record, lake water level has remained below the conservation pool elevation (2,936.50 ft amsl or 895.05 m amsl). The conservation pool elevation is the maximum normal operating level, and water storage above this level is used to regulate floodwaters. Above an elevation of 2,965.00 ft amsl (903.73 m amsl), a water level referred to as the top of flood control pool, releases “at a maximum rate possible” are required as part of the Bureau of Reclamation's flood control operations. The maximum water level recorded for Lake Meredith was 2,908 ft amsl (> 886 m amsl), occurring in August 1999. The lake level dipped below dead pool May 2011–June 2014 but has since recovered.

Figure 4. Daily Lake Meredith water level elevation in water year 2023 with dead pool elevation and the water years 2001–2020 average daily mean, maximum, and minimum levels.

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Lake Meredith National Recreation Area

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Groundwater

Groundwater is one of the most critical natural resources of the Southern Plains and American Southwest, providing drinking water, irrigating crops, and sustaining rivers, streams, and springs throughout the region.

Methods

Lake Meredith National Recreation Area groundwater is monitored annually at one well (0627401) by the Texas Water Development Board (TWDB) and the data are available at the TWDB Database.

Recent Findings

Well 0627401 was monitored on 2 November 2023 at 119.8 feet below ground surface (ft bgs; 36.5 m bgs), 0.6 ft (0.2 m) lower than the measurement made in WY2022 (Table 1). Water levels in this well have shown a gradual declining trend since routine monitoring began in WY2001 (Figure 5). This well is located near the Canadian River, upstream of Lake Meredith, and does not appear to be directly influenced by lake water levels.

Table 1. Groundwater Monitoring Results (click to view data)

Table 1. Groundwater monitoring results in water year 2023 (WY2023), Lake Meredith National Recreation Area (amsl = above mean sea level; bgs = below ground surface).

State Well Number	Wellhead Elevation (ft amsl)	Mean Depth to Water (ft bgs)	Water Level Elevation (ft amsl)	Change in Elevation From WY2020 (±  ft)	Change in Elevation From Earliest Measurement in WY1972 (±  ft)	Elevation Difference From Lake Meredith Level (±  ft)
0627401	3,053.00	119.80	2,933.20	−0.60	−6.38	+50.89

Figure 5. Depth to water (feet below ground surface; ft bgs) at one groundwater monitoring well in water years 2001–2023, Lake Meredith National Recreation Area.

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Past Reports

Water Year 2022 Climate and Water Monitoring at Lake Meredith National Recreation Area

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Authors: Kara Raymond, Andy Ray

Please cite this report as
Raymond, K., and A. Ray. 2024. Climate and Water Monitoring at Lake Meredith National Recreation Area: Water Year 2023. Southern Plains Network, National Park Service, Pecos, New Mexico.