Article

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

A boat speeds its way across Lake Meredith.
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., WY2022 runs from October 2021 through September 2022). This article reports the results of climate and water monitoring at Lake Meredith National Recreation Area (Figure 1) in WY2022.

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

Map of Lake Meredith National Recreation Area showing weather station on the north end of the park by the lake, lake level gage near the weather station, and groundwater monitoring well on the south end of the park, about 10 mi away from the lake.
Figure 1. Monitored weather station, lake level gage, and groundwater well at Lake Meredith National Recreation Area in WY2022.

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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 (NOAA) Cooperative Observer Program (COOP) weather station (Sanford Dam 418040) has been operational at Lake Meredith National Recreation Area since 1993 (see 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.

Green and red hills with vibrant foliage in the foreground.
Lake Meredith National Recreation Area

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Results for Water Year 2022

Precipitation

Annual precipitation at Lake Meredith National Recreation Area in WY2022 was 10.96″ (27.8 cm; Figure 2), which was 8.26″ (21.0 cm) less than the long-term annual average. Monthly precipitation totals in WY2022 were less than the long-term averages in all months. October–April and September were substantially drier than normal, receiving ≤46% of average. Extreme daily rainfall events (≥ 1 in; 2.54 cm) occurred on one day, much less than the average annual frequency of 4.8 days. The single extreme rainfall event occurred on 09 June 2022 (1.13 in; 2.9 cm).

Air Temperature

The mean annual maximum temperature at Lake Meredith National Recreation Area in WY2022 was 77.6°F (25.3°C), 3.6°F (2.0°C) above the long-term normal. The mean annual minimum temperature in WY2022 was 44.0°F (6.7°C), 1.4°F (0.8°C) above the long-term average. Mean monthly maximum and minimum temperatures in WY2022 were warmer than average for most of the year and differed by as much as 11.9°F (6.6°C; see December as an example) relative to the long-term monthly averages (Figure 2). February was the only month that both mean maximum and minimum temperatures were cooler than average. Extremely hot temperatures (≥ 100°F; 37.8°C) occurred on 46 days on in WY2022, nearly twice the average frequency of 24.7 days. Extremely cold temperatures (≤ 18°F; -7.8°C) occurred on 32 days, approximately 70% more than the average frequency of 18.6 days.

Climogram showing precipitation and air temperature over time. Monthly precipitation totals for water year 2022 are lower than the 1991–2020 average in all months.
Figure 2. Climogram showing monthly precipitation and mean maximum and minimum temperatures in water year 2022 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 WY2022 was drier than the WY1994–2022 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.

Bar graph showing departures from average wet/dry conditions. Conditions were drier than average for the three most recent years.
Figure 3. Reconnaissance drought index for Sanford Dam station at Lake Meredith National Recreation Area, water years 1994–2022. Drought index calculations are relative to the time period selected (1993–2022). 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. Gage data are available from the USGS.

A crane flies low over reddish-brown water.
Crane at Harbor Bay, Lake Meredith.

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Recent Findings 

Mean lake level in WY2022 was 2,883.94 ft (879.02 m) above mean sea level (amsl) with a range of 2,881.71 to 2,886.31 ft amsl (878.34–879.75 m amsl; Figure 4). Lake level in WY2022 remained above the WY2001–2020 average lake level and the dead pool elevation (2,850.00 ft amsl; 868.68 m amsl) for the entire year. Dead pool elevation is the level below which water cannot be drained by gravity to the downstream river. Lake level dipped below dead pool elevation from May 2011–June 2014, but has since recovered. For the entire monitoring record lake water level has remained below the conservation pool elevation (2936.50 ft; 895.05 m), which is the maximum normal operating level. Water storage above this level is used to regulate floodwaters.

Lake Meredith water level in water year 2022 was above the Dead Pool and water years 2001–2020 Minimum and Average water elevations.
Figure 4. Daily Lake Meredith water level elevation in water year 2022 with dead pool elevation and the water years 2001–2020 average daily mean, maximum, and minimum levels.

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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 11 November 2021 at 119.2 feet below ground surface (bgs), 0.2 ft lower than the measurement made in WY2021 (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 the level of the lake.

Line graph showing a declining water level over the monitoring record.
Figure 5. Depth-to-water (feet below ground surface) at one groundwater monitoring well in water years 2001–2022, Lake Meredith National Recreation Area.

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This article was created by the Southern Plains Inventory and Monitoring Network.
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 2022. Southern Plains Network, National Park Service, Pecos, New Mexico.

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Lake Meredith National Recreation Area

Last updated: September 19, 2024