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Climate and Water Monitoring at Tonto National Monument: Water Year 2022

The historic walls and cave opening of the lower cliff dwellings at Tonto National Monument.
The Lower Cliff Dwelling at Tonto National Monument.

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Overview

Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and surface water is key to assessing the condition of park natural resources—and often, cultural resources.

At Tonto National Monument (Figure 1), Sonoran Desert 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 Tonto National Monument, we monitor climate and springs among other vital signs.

Surface-water 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 Tonto National Monument (Figure 1) in WY2022.

Map of Tonto National Monument showing location of weather station near the center of the park.
Figure 1. Monitored weather station at Tonto National Monument.

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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.

A National Oceanic and Atmospheric Administration (NOAA) Cooperative Observer Program (COOP) weather station, “Roosevelt 1 S” (ID# 027281), had been operational three miles (4.8 km) from Tonto National Monument since 1905. In 2019, this station was relocated to Tonto National Monument (Figure 1). Due to this geographical move, current weather data from this station is no longer directly comparable to the long-term climate dataset. As a substitute, climate analyses in this year’s report use 30-year averages (1991–2020) and gridded surface meteorological (GRIDMET) data from the location of the station.

GRIDMET is a spatial climate dataset at a 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 and that assigned to a grid cell. Data from both weather station and GRIDMET are accessible through Climate Analyzer.

Results for Water Year 2022

Precipitation

Annual precipitation at Tonto National Monument in WY2022 was 10.59″ (26.9 cm; Figure 2), which was 2.90″ (7.4 cm) less than the 1991–2020 annual average. The deficit primarily occurred October–May, when monthly totals were all less than the 1991–2020 monthly averages—except in December, which received nearly twice the average rainfall. Overall monsoonal rains (June–September) were slightly above the 1991–2020 average, with June receiving over three times the monthly average.

Air Temperature

The mean annual maximum temperature at Tonto National Monument in WY2022 was 82.8°F (28.2°C), 0.2°F (0.1°C) above the 1991–2020 average. The mean annual minimum temperature in WY2022 was 56.1°F (13.4°C), 0.3°F (0.2°C) above the 1991–2020 average. Mean monthly maximum and minimum temperatures in WY2022 were variable relative to average. While temperatures were frequently near average, deviations from 1991–2020 monthly averages of up to 7.0°F (3.9°C) occurred (Figure 2).

Climogram showing precipitation and air temperature over time. Monthly precipitation totals in WY2022 are less than 1991–2020 average monthly totals in all but three months.
Figure 2. Climogram showing monthly precipitation and mean maximum and minimum temperature of WY2022 compared to the 1991–2020 averages at Tonto National Monument. Data source: GRIDMET via 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 Tonto National Monument indicates that WY2022 was drier than the 1991–2022 annual average for the third consecutive year 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. Starting in water year 2020, conditions have since been drier than average.
Figure 3. Reconnaissance drought index for Tonto National Monument, WY1991–2022. Drought index calculations are relative to the time period selected (1990–2022). Choosing a different set of start/end points may produce different results. Data source: GRIDMET via climateanalyzer.org.

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Springs

Background

Springs, seeps, and tinajas (small pools in a rock basin or impoundments in bedrock) are small, relatively rare biodiversity hotspots in arid lands. They are the primary connection between groundwater and surface water and are important water sources for plants and animals. For springs, the most important questions we ask are about persistence (How long was there water in the spring?) and water quantity (How much water was in the spring?).

A man stands next to a small pool that drains in a narrow path down a slope. He points to the center of the pool for the camera.
Figure 4. Cave Canyon Spring at Tonto National Monument, March 2022.

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Recent Findings at Cave Canyon Spring

Cave Canyon Spring is a rheochrene spring (emerges as a flowing stream) located within the main drainage of Cave Canyon between the Upper and Lower Cliff Dwellings. When visited and last characterized on 23 March 2022, Cave Canyon Spring emerged as a series of small, shallow pools (Figure 4) linked by a shallow springbrook within the active channel (Figure 5). Cave Canyon Spring is one of the most dynamic perennial springs in the Sonoran Desert parks, with highly variable springflow and wetted extent, likely due to the influence of periodic scour/sedimentation events in the Cave Canyon drainage (Albrecht et al. 2005). Descriptions and other characteristics of springs are updated every five years.

Reference: Albrecht, E.W. and Others. 2005. A Biological Inventory and Hydrological Assessment of the Cave Springs Riparian Area, Tonto National Monument, Arizona. USGS Southwest Biological Science Center, Sonoran Desert Research Station, University of Arizona. Tucson, Arizona

A series of small pools line the bottom of a drainage, surrounded by tree litter and branches.
Figure 5. Cave Canyon Spring is currently a series of small pools connected by a shallow springbrook and subsurface flow. Note recent deposition of sediment and large cobbles. Tonto National Monument, March 2022.

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Site Condition

Consistent with past years, we rated Cave Canyon Spring as “moderately disturbed” because of the presence of the Upper Cliff Dwelling Trail, which lies within a few meters of the spring. For the first time in WY2022, Cave Canyon Spring was “highly disturbed” from recent flooding, as shown by substantial shifts in channel morphology since our visit in WY2021 and heavy accumulations of sediment and woody debris in and around the site. We did not note any other natural or human-caused disturbances at Cave Canyon Spring in WY2022.

As in previous years, we did not observe crayfish or bullfrogs (invasive aquatic animals) in WY2022. However, scattered patches of the non-native grasses ripgut (Bromus diandrus) and red brome (B. rubens) were detected around Cave Canyon Spring in WY2022, similar to most previous visits.

The obligate wetland tree Arizona sycamore (Platanus wrightii) was also observed at Cave Canyon Spring in WY2022, as it has been in previous years.

Inventory of Rare and Invasive Species and Pathogens

Four water samples were collected from Cave Canyon Spring on 23 March 2022. None of our target organisms were detected.

Water Quantity

The WY2022 visit occurred on 23 March 2022, and the spring contained water. The water temperature sensor and housing were not relocated during the March 2022 visit, and recent scour and sedimentation evidence in the channel suggested that flooding may have swept the sensors away or buried them, as appeared to have occurred in WY2019 and WY2020 (Figure 3). In prior water years, when the temperature sensor and housing were relocated, the spring was wetted 100% of the days measured.

Graphic indicating that Cave Canyon Spring was wetted since 2017 except for periods of missing data, particularly in 2019–2020 and 2021–2022.
Figure 6. Water persistence in Cave Canyon Spring, Tonto National Monument. The water sensor and housing were absent when visited in March of WY2022, and likely washed downstream in a flooding event earlier in the water year.

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Unlike in previous years, discharge could not be measured at Cave Canyon Spring in WY2022 due to negligible surface flow.

Wetted extent was evaluated using a method for flowing water. The total brook length was 10 m (33 ft)—much shorter than previous measurements (Table 1). However, Albrecht et al. (2005) refer to periods in the past during which Cave Canyon Spring was “buried” by sedimentation events (resulting in no surface water), only to be uncovered and surface flow restored by subsequent scour events.

Width and depth averaged 94.7 cm (37.3 in) and 6.7 cm (2.6 in), respectively—generally wider and deeper than previous measurements (Table 1). When considered with the observed flooding evidence from WY2021 and WY2022, these dramatic shifts in wetted extent parameters at Cave Canyon Spring suggest a return to the dynamic geohydrology conditions following channel erosion/deposition events in the early 2000s as documented by Albrecht et al. (2005).

Water Quality

Core water quality (Table 2) and water chemistry (Table 3) data were collected at the primary sampling location of Cave Canyon Spring, the largest pool within the spring complex. This location was re-established in WY2022 because the original location was buried in sediment. Specific conductance, total dissolved solids, and alkalinity were on the high end of the range observed in other perennial springs we monitor in the Sonoran Desert parks.

Cave Canyon Spring Data Tables

Past Findings

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    Article created by the Sonoran Desert Inventory and Monitoring Network.

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    Tonto National Monument

    Last updated: May 31, 2024