Springs Monitoring at Tonto National Monument: 2024
Bryn Callie, Annika Munson, Cheryl McIntyre, Andy Hubbard
Edited by Tani Hubbard
Please cite this publication as:
Callie, B., A. Munson, C. McIntyre, and A. Hubbard. 2026. Springs Monitoring at Tonto National Monument: 2024. Science Report NPS/SR—2026/450. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2318593
Abstract
The Sonoran Desert Inventory and Monitoring Network monitors one spring—Cave Dweller Spring—at Tonto National Monument, Arizona. We assess the condition of the site, measure spring discharge and wetted extent (area that contained water), collect core water quality and water chemistry data, note the wetland plants and invasive plants and animals present, and sample for environmental DNA (eDNA) to inventory springs for rare species, invasive species, and pathogens. Each spring is somewhat unique, and Arizona has not adopted water quality standards that apply across the diversity of springs in the state. We continue to collect water quality data at the springs to form a baseline reference of natural variance. We did not detect any of our eDNA target organisms at Cave Dweller Spring in 2024. Cave Dweller Spring is a shallow springbrook connecting a series of small pools. The amount of water and flow are highly variable at this spring because of periodic flooding. The spring contained water when we visited in 2024, but we do not have persistence data for the year because the temperature sensor was missing. Given the scouring and sedimentation at the spring, we assume the temperature sensor was washed away in a flood event, which has happened in prior years as well. In years when we were able to retrieve the sensor, the spring had water year round. We found a matrix of red brome (invasive plant), similar to prior years, and wetland plants included sycamore and willow.
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Background
Springs, seeps, and tinajas (discrete 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. At Tonto National Monument, 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. We monitor one spring at Tonto National Monument each year. 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?).
Climate change is an emerging influence on springs in the American Southwest. Possible changes include increased air temperatures, evaporation rates, and drought intensity; more frequent and extreme rainfall and heat events; and potentially reduced precipitation in the winter and spring. These changes may cause springs to experience reduced flow or even go dry, which may disrupt ecological functions, reduce species diversity, and negatively impact visitor experience.
Springs reporting is by calendar year starting in 2024. Prior to 2024, springs data were summarized by water year (WY), which ran from October through September (e.g., WY2023 started in October 2022 and went through September 2023). In 2024, springs sampling at Tonto National Monument occurred on 15 May. Water persistence is monitored continuously throughout the year, but in this report we only present 2024 persistence data up to the sampling visit date for Cave Dweller Spring.
Methods
Sonoran Desert Network springs monitoring is organized into the four modules described below (see McIntyre et al. 2018 for additional details) and eDNA inventories. All data have undergone certification processes to ensure they have been verified and validated for accuracy, are complete, and are fully documented. Data used in this report are available to park staff on the NPS DataStore and can be provided upon request.
Site Characterization
This module provides context for interpreting change in the other modules. We record GPS locations, draw a site diagram, and describe the spring type (e.g., helocrene, limnocrene, rheocrene, or tinaja) and its associated vegetation in this module. Helocrene springs emerge as low-gradient wetlands, limnocrene springs emerge as pools, and rheocrene springs emerge as flowing streams. This module is completed once every five years or after significant events.
Site Condition
We estimate the level of natural and anthropogenic disturbances and the level of stress on vegetation and soils at the spring on a scale of 1–4, where 1 = undisturbed, 2 = slightly disturbed, 3 = moderately disturbed, and 4 = highly disturbed. Types of natural disturbances can include flooding, drying, fire, wildlife impacts, windthrow of trees and shrubs, beaver activity, and insect infestations. Anthropogenic disturbances can include roads, off-highway vehicle trails, hiking trails, livestock and feral-animal impacts, removal of invasive non-native plants, flow modification, and other evidence of human use of the spring site. We take repeat photographs from the same location and perspective to show the spring and its landscape context. We note the presence of certain obligate wetland plant species (plant species that almost always occur only in wetlands), facultative wetland plant species (plant species that usually occur in wetlands, but also occur in other habitats), and invasive non-native crayfish and American bullfrog (Rana catesbeiana). We also record the density of invasive non-native plants using a qualitative scale (1–5 plants, scattered patches, evenly distributed patches, or a matrix). We complete the site condition module during each springs monitoring visit.
Water Quantity
We measure the persistence of surface water, amount of spring discharge, and wetted extent (area that contained water). To estimate persistence, we analyze the variance of temperature measurements taken by two logging thermometers placed at or near the orifice (spring opening). Because water mediates variation in diurnal temperatures, data from a submerged sensor will show less daily variation than data from an exposed, open-air sensor; this tells us when the spring was wet or dry. Surface discharge is measured with a timed sample of water volume. Wetted extent is a systematic measurement of the physical length (up to 100 m), width, and depth of surface water. It is assessed using a technique for either standing water (e.g., limnocrene and helocrene springs) or flowing water (e.g., rheocrene springs). We complete discharge and wetted extent measurements during each visit when possible. Water persistence measurements are continuous throughout the year.
Water Quality
We measure core water quality and water chemistry parameters. Core water quality parameters include water temperature, pH, specific conductivity (a measure of dissolved compounds and contaminants), dissolved oxygen (how much oxygen is present in the water), and total dissolved solids (an indicator of potentially undesirable compounds). Discrete measurements of these parameters are collected with a multiparameter meter. If the meter fails calibration checks, we do not present data. Water chemistry is assessed by collecting surface water samples and estimating the concentration of major ions with a photometer in the field. These parameters are collected at one or more sampling locations within a spring, but we only present data for the primary sampling location. Each perennial spring is somewhat unique, and Arizona has not adopted applicable water quality standards for most perennial springs, including Cave Dweller Spring. Ongoing, long-term data collection at each spring will improve our understanding of the natural range in water quality and water chemistry parameters for a given site. We complete the water quality module during each visit when possible. The total number of measurements value we present in the data tables is across all years and may reflect multiple measurements taken in a single year and missing values in other years for a variety of reasons.
eDNA Inventory of Rare Species, Invasive Species, and Pathogens
We inventory rare species, invasive species, and pathogens in perennial springs using environmental DNA (eDNA) techniques. One or more 5-liter water samples are collected and filtered (using a 5 µm self-preserving mesh filter) from Cave Dweller Spring using a Smith Root Citizen Science Pump. Samples are preserved in ethanol prior to DNA extraction and analysis by the Goldberg Lab at Washington State University.
Target Organisms for the eDNA Project
The invasive non-native American bullfrog (Rana catesbeiana), which has not been previously confirmed within the park (Albrecht et al. 2007).
The pathogen chytrid fungus (Batrachochytrium dendrobatidis), a major threat to amphibians globally that is currently expanding in the American Southwest. American bullfrog is an important vector of chytrid fungus and ranaviruses. Chytrid has not previously been detected at the park.
Ranaviruses, pathogens that can infect amphibians and produce 90–100% mortality in tadpoles and adults and can persist in affected wetlands. Ranaviruses have not been previously detected at the park.
The native Chiricahua leopard frog (Rana chiricahuensis), a federally designated threatened species that has not been previously documented at the park (Albrecht et al. 2007). Designated critical habitat is located in nearby Tonto Creek and the Mogollon Rim.
The native lowland leopard frog (Rana yavapaiensis), a species of conservation concern that has not been previously confirmed within Tonto National Monument (Albrecht et al. 2007).
The native aquatic northern Mexican garter snake (Thamnophis eques megalops), a federally designated threatened species that has not been previously observed within the park (Albrecht et al. 2007). Designated critical habitat is found in nearby Tonto Creek.
The native jaguar (Panthera onca), a federally designated endangered species with a historical range that included the Tonto Basin. Designated critical habitat for jaguar recovery is located in southern Arizona adjacent to Tucson.
Results
Cave Dweller Spring
Cave Dweller Spring (Figures 1 and 2) is a rheocrene spring (a spring that emerges into one or more stream channels) located within the main drainage of Cave Canyon between the Upper Cliff Dwelling and Lower Cliff Dwelling at Tonto National Monument. When visited and last characterized on 23 March 2022, Cave Dweller Spring was described as a shallow springbrook with an active channel connecting a string of small pools. Spring characterizations are updated every five years. This spring is one of the more dynamic perennial springs in the Sonoran Desert parks, with highly variable springflow and wetted extent (area that contains water), likely because of the influence of periodic sedimentation events in the spring drainage (Albrecht et al. 2005). The 2024 visit to Cave Dweller Spring occurred on 15 May 2024, and the spring contained water.
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Site Condition
In 2024, we observed many dead European honeybees on the water surface along with live bees. Consistent with past visits, we noted slight disturbance related to hiking trails based on the presence of the Upper Cliff Dwelling Trail, which runs parallel to the spring about five meters upslope. We rated the spring as slightly disturbed by recent flooding with evidence of a mild scour and sedimentation event that occurred sometime between April 2023 and May 2024 (Figure 3). The site is prone to flooding and in past years we have rated it anywhere from undisturbed to highly disturbed by flooding. There were no other natural or human-caused disturbances observed at Cave Dweller Spring in 2024.
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As in past years, we did not observe invasive non-native crayfish or American bullfrog (Rana catesbeiana) at Cave Dweller Spring in 2024. We observed one invasive non-native plant species: a matrix of red brome (Bromus rubens, evenly distributed patches observed between 2017 and 2023, but density was not assessed in some of those years; Figure 3).
We observed two species of obligate wetland plants at Cave Dweller Spring in 2024: Arizona sycamore (Platanus wrightii, a tree previously observed in 2017–2023) and willow (Salix sp., a tree/shrub previously observed in 2018–2021).
eDNA Inventory of Rare Species, Invasive Species, and Pathogens
Five water samples were collected and filtered at Cave Dweller Spring during the May 2024 site visit. None of our target organisms were detected.
Water Quantity
Sensors are deployed and data are downloaded during our annual visit; the dates of these visits are indicated by black diamonds in the persistence graph (Figure 4). The water temperature sensor and housing deployed at Cave Dweller Spring in April 2023 were not found during our May 2024 visit. Given the evidence of scouring and sedimentation we observed at the site in 2024, it is likely that the sensor was washed away in a flooding event sometime between the two visits. Therefore, there is no estimate of persistence for Cave Dweller Spring for 2024. In prior years, the spring was wetted (contained water) 100% of the days measured across entire years.
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Discharge was not measured at Cave Dweller Spring in 2024 as there was no surface outflow from the pools when visited. Past data are summarized in Table 1. In 2024, wetted extent was evaluated using a method for flowing water. The springbrook length was 56.8 m (186.4 ft). Width and depth along the springbrook averaged 43.8 cm (17.2 in) and 4.7 cm (1.9 in), respectively. All three wetted extent measurements were within the ranges of previously recorded values, although width was near the lower end of the range (Table 2).
| Sampling Location |
2024 Mean (Range of Prior Means) |
Prior Years Measured (# of Visits with Measurements) |
|---|---|---|
| 002 | c.n.s. (5.9–11.4) | 2017–2021 (4) |
| Measurement | 2024 Value (Range of Prior Values/Means) |
Prior Years Measured (# of Visits with Measurements) |
|---|---|---|
| Width (cm) | 43.8 ± 41.0 (42.9–94.7) | 2017–2023 (6) |
| Depth (cm) | 4.7 ± 7.9 (1.5–6.7) | 2017–2023 (6) |
| Length (m) | 56.8 (10.3–95.0) | 2017–2023 (6) |
Water Quality
Core water quality (Table 3) and water chemistry (Table 4) data were collected at the primary sampling location. In 2024, the dissolved oxygen level was lower than previously recorded. Total dissolved solids, specific conductivity, and temperature values were higher than in prior years. The pH was within the range of previously recorded values. Alkalinity, magnesium, potassium, and sulphate levels were lower and the chloride level was higher than in prior years. Calcium was within the range of prior measurements.
| Sampling Location | Parameter | 2024 Value (Range of Prior Values) |
Prior Years Measured (# of Measurements) |
|---|---|---|---|
| 004 | Dissolved oxygen (mg/L) | 2.49 (5.26–7.34) | 2022–2023 (2) |
| 004 | pH | 7.27 (6.98–7.29) | 2022–2023 (2) |
| 004 | Specific conductivity (µS/cm) | 573 (538–547) | 2022–2023 (2) |
| 004 | Temperature (°C) | 21.0 (18.6–18.8) | 2022–2023 (2) |
| 004 | Total dissolved solids (mg/L) | 372 (349–355) | 2022–2023 (2) |
| Sampling Location | Parameter | 2024 Value (Range of Prior Values) |
Prior Years Measured (# of Measurements) |
|---|---|---|---|
| 004 | Alkalinity (CaCO3) | 245 (250–255) | 2022–2023 (2) |
| 004 | Calcium (Ca) | 58 (44–68) | 2022–2023 (2) |
| 004 | Chloride (Cl) | 51 (42–45) | 2022–2023 (2) |
| 004 | Magnesium (Mg) | 21 (25–29) | 2022–2023 (2) |
| 004 | Potassium (K) | 2.0 (2.1–3.1) | 2022–2023 (2) |
| 004 | Sulphate (SO4) | 5 (6–7) | 2022–2023 (2) |
Past Reports
Previous annual reports can be found at the following links:
Literature Cited
Albrecht, E.W., B.F. Powell, W.L. Halvorson, and C.A. Schmidt. 2007. Vascular plant and vertebrate inventory of Tonto National Monument. U.S. Geological Survey Open-File Report 2007-1295. USGS, Southwest Biological Science Center, Sonoran Desert Research Center, Sonoran Desert Research Station, University of Arizona, Tucson, Arizona.
Albrecht, E.W., W.L. Halvorson, P.P. Guertin, B.F. Powell, and C.A. Schmidt. 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. https://irma.nps.gov/DataStore/Reference/Profile/2301065
McIntyre, C., K. Gallo, E. Gwilliam, J.A. Hubbard, J. Christian, K. Bonebrake, G. Goodrum, M. Podolinsky, L. Palacios, et al. 2018. Springs, seeps, and tinajas monitoring protocol: Chihuahuan and Sonoran Desert Networks. Natural Resource Report. NPS/CHDN/NRR—2018/1796. National Park Service. Fort Collins, Colorado. https://irma.nps.gov/DataStore/Reference/Profile/2257245
Author Information
Bryn Callie 1
Annika Munson 1
Cheryl McIntyre
1 
https://orcid.org/0000-0001-7554-7586
Andy Hubbard 1 https://orcid.org/0000-0002-4223-7730
Edited by Tani Hubbard 2
https://orcid.org/0009-0009-8777-4773
1 National Park Service
Sonoran Desert Inventory and Monitoring Network
12661 E. Broadway Blvd.
Tucson, Arizona
2
Northern Rockies Conservation Cooperative and National Park
Service
12661 E. Broadway Blvd.
Tucson, Arizona
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