Climate and Water Monitoring at Amistad National Recreation Area: Water Year 2024

Kara Raymond, Susan Singley, Tani Hubbard

Please cite this publication as:

Raymond, K., S. Singley, and T. Hubbard. 2026. Climate and Water Monitoring at Amistad National Recreation Area: Water Year 2024. Science Report NPS/SR—2026/485. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2318783

Abstract

The Chihuahuan Desert Inventory and Monitoring Network monitors climate, reservoir level, groundwater, and four springs each year at Amistad National Recreation Area, Texas. We report on climate and water resources together because surface water conditions are closely related to climate conditions. Climate data, including temperature, precipitation, and reconnaissance drought index, are retrieved from The Climate Analyzer (climateanalyzer.org). We track groundwater levels in six wells in and near the park. We pull groundwater well and reservoir level data from the Texas Water Development Board database. We assess the condition of each spring, measure spring discharge and wetted extent (area that contained water), collect core water quality and water chemistry data, note the wetland species and invasive species, and sample for environmental DNA (eDNA) to inventory springs for rare species, invasive species, and pathogens. Each spring is somewhat unique, and Texas has not adopted water quality standards that apply across the diversity of springs in the state. We collect water quality data at the springs to form a baseline reference of natural variance. After average rainfall in the fall of WY2024, precipitation was below average for the rest of the year. The drought index indicated the park was drier than average for the fourth year in a row. High temperatures were largely above average, and low temperatures were above average fall through spring and below average in summer. There were 50% more extremely hot days in WY2024. Amistad Reservoir levels were below the 1991–2020 daily minimum level, and groundwater decreased in all four measureable wells. All four monitored springs were experiencing drier conditions in WY2024. The orifices were not flowing at Big Satan Canyon Spring, and the wetted area was smaller than in prior years. Dead Man’s Canyon Spring had water, but pools were not overflowing as has been typical. Only one orifice at Indian Springs Canyon Spring had water, and the wetted area of the springbrook was significantly smaller in 2024. Mouth of the Pecos Spring was completely dry and the plants were visibly stressed. We observed new invasive plants at three of the springs: turkey tangle fogfruit, Bermuda grass, common weed, and spiny sowthistle at Big Satan Canyon Spring; turkey tangle fogfruit at Indian Springs Canyon Spring; and common reed and hedgeparsley at Mouth of the Pecos Spring. Two of our eDNA target species, Mexican blindcat and Rio Grande leopard frog, were detected at Dead Man’s Canyon Spring.

A large, rippling, blue lake lined by sheer rock cliffs topped by desert vegetation. A long bridge crosses the lake in the distance.
Amistad Reservoir at Amistad National Recreation Area.

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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 Amistad National Recreation Area (Figure 1), Chihuahuan Desert 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 resource problems, allowing managers to mitigate them before they become worse. At Amistad National Recreation Area, we monitor climate, reservoir level, groundwater, and springs, 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., WY2024 runs from October 2023 through September 2024). In this report, we present the results of climate and water monitoring at Amistad National Recreation Area in WY2024.

Figure 1. Map of Amistad National Recreation Area showing 6 groundwater wells and one weather station in and around the park. Four wells and the weather station are along the reservoir in the southeast section of the park, one well is on the Devils River, and one well is on the Pecos River.
Figure 1. Monitored weather station and groundwater wells at Amistad National Recreation Area.

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Climate and Weather

There is often confusion over the terms “weather” and “climate.” In short, weather describes short-term 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 (Amistad Dam #410225) has been operational at Amistad National Recreation Area since 1964 (Figure 1). This station provides a reliable, long-term climate dataset for analyses in this climate and water report. Data from this station are accessible through The Climate Analyzer.

Results

Precipitation and Air Temperature

Highlights: Rainfall was below average except in the fall. Overall, high and low temperatures were above average except in summer when the lows were below average. There were 50% more extremely hot days.

Annual precipitation at Amistad National Recreation Area in WY2024 was 9.51″ (24.16 cm), 9.92″ (25.20 cm) less than the 1991–2020 annual average. Average monthly precipitation totals (Figure 2) in October–December were similar to the long-term averages. Drier than average conditions occurred throughout the rest of the water year. Monthly precipitation totals for January–September were below the 1991–2020 averages by 41–92%. The largest monthly deficit occurred in May, which received 2.39″ (6.07 cm) less than average. An extreme daily rainfall event (≥1.00″; 2.54 cm) occurred once in WY2024, four fewer days than the average annual frequency of 5.1 days. The only extreme rainfall event occurred on 04 September 2024 (1.06″; 2.69 cm). The mean annual maximum temperature in WY2024 was 83.4°F (28.6°C), 2.3°F (1.2°C) above the 1991–2020 average. The mean annual minimum temperature in WY2024 was 58.7°F (14.8°C), 0.7°F (0.4°C) above the long-term average. Mean monthly maximum and minimum temperatures in WY2024 (Figure 2) differed by as much as 6.7°F (3.7°C; see May as an example) relative to the 1991–2020 monthly averages. Mean monthly maximum temperatures were above average in every month except November, January, and July. Mean monthly minimum temperatures were above average from October through May, except January, and below average from June through September. Extremely hot temperatures (≥102.0°F; 38.9°C) occurred on 32 days in WY2024, nearly 50% more than the average frequency of 21.5 days. Extremely cold temperatures (≤35.0°F; 1.7°C) occurred on 19 days, one less than the average frequency of 20.1 days.

Figure 2. Climogram showing monthly precipitation totals for WY2024 are below those for 1991–2020 in every month except October and December. Maximum temperatures for WY2024 are above the 1991–2020 average in every month except November, January, and July. Minimum temperatures for WY2024 are above the 1991–2020 average in every month except January and June through September.
Figure 2. Climogram showing monthly precipitation and mean maximum and minimum air temperatures in water year (WY) 2024 and the 1991–2020 averages at Amistad Dam station, Amistad National Recreation Area. Data source: The Climate Analyzer; climateanalyzer.org.

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Drought

Highlight: WY2024 was the fourth consecutive year of drier than average conditions.

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 Amistad National Recreation Area indicates WY2024 was drier than the 1991–2024 average for the fourth consecutive year from the perspective of both precipitation and potential evapotranspiration (Figure 3).

Figure 3. Bar graph showing that conditions during the four most recent water years are drier than the 1991–2024 average.
Figure 3. Reconnaissance drought index for Amistad Dam station at Amistad National Recreation Area, water years (WY) 1991–2024. Drought index calculations are relative to the time period selected (1990–2024). Choosing a different set of start/end points may produce different results. N/A = insufficient data to generate reliable estimates. Data source: The Climate Analyzer; climateanalyzer.org.

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Reservoir Level

The Amistad International Reservoir was formed by the construction of Amistad Dam between 1964 and 1969. Reservoir level is not a Chihuahuan Desert Network vital sign; however, it is included in this report because the reservoir level has implications for park resources throughout Amistad National Recreation Area, including groundwater and springs.

Methods

The International Boundary and Water Commission (IBWC) has operated a water level gage at Amistad Reservoir (International Amistad Reservoir Storage Station Number 08-4508.00) since 1968 when filling began. The gage is located at the downstream end of the reservoir. Every 15 minutes, the gage collects water level data, which are available from the IBWC and the Texas Water Development Board (TWDB).

Results

In WY2024, mean reservoir level was 1,054.46 feet above mean sea level (ft amsl; 321.40 m amsl) with a range of 1,046.96 to 1,066.00 ft amsl (319.11 to 324.92 m amsl; Figure 4). During the entire year, reservoir level remained below the flood pool elevation of 1,140.4 ft amsl (347.59 m amsl; elevation of flood gates and emergency spillway) and the conservation pool elevation of 1,117.0 ft amsl (340.46 m amsl; maximum normal operating level, above which the storage is used to regulate floodwaters). Daily reservoir water level in WY2024 was on average 62.54 ft (13.14 m) below the conservation pool. Throughout the year, the reservoir ranged from 24 to 39% full. During most of the water year, reservoir level was below the 1991–2020 daily minimum level.

Figure 4. Line graph showing the daily mean Amistad Reservoir level in WY2024 was below the 1991–2020 minimum for most of the year.
Figure 4. Daily Amistad Reservoir water level elevation in water year (WY) 2024 with the flood and conservation pool elevations and the 1991–2020 average daily mean and range.

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Groundwater 

Groundwater is one of the most critical natural resources of the American Southwest. It provides drinking water, irrigates crops, and sustains rivers, streams, and springs throughout the region.

Methods

Groundwater is monitored at Amistad National Recreation Area in six wells in or near the park (Figure 1). Each well is monitored annually by the Texas Water Development Board (TWDB), and the data are available at the TWDB Database.

Results

Highlight: Groundwater decreased in all four measurable wells.

Two wells could not be measured in WY2024: well 7140201 was not measured because of a possible well collapse, and well 7140307 was not measured because TWDB was unable to access the well site. The other four wells were monitored in February 2024. WY2024 groundwater levels decreased in all four wells compared to WY2023 measurements (Table 1, Figure 5).

  • Groundwater levels in wells 7033302 and 7033508 decreased by 10.28 ft (3.1 m) and 11.01 ft (3.4 m), respectively, similar to the decreases the previous year. These results coincide with a large decrease (29.97 ft; 9.14 m) in reservoir level that occurred between the WY2023 and WY2024 groundwater sampling events. Both wells are near the southern edge of the reservoir and have historically tracked with the reservoir level.

  • The WY2024 groundwater level in well 7017403 was 0.24 ft (0.07 m) lower than the previous year.

  • Well 7122403 showed a large decrease between WY2022 and WY2024 (36.55 ft, 11.14 m). This well is up gradient of the reservoir, adjacent to the Devils River, and its water level is substantially higher than the reservoir level. The previous measurements at well 7122403 were relatively stable and did not appear to be influenced by changing reservoir level.

Table 1. Groundwater monitoring results in water year (WY) 2024, Amistad National Recreation Area. N/A = the measurement could not be collected; amsl = above mean sea level; bgs = below ground surface.
State Well Number Location Wellhead Elevation (ft amsl) Depth to Water
(ft bgs)		 Water Level Elevation
(ft amsl)		 Elevation Change from WY2023
(ft)		 Elevation Difference from Amistad Reservoir Level (ft)
7017403 15.6 miles NNE of dam on Devils River 1,180 62.83 1,117.17 −0.24 +65.19
7033302 9.2 miles ENE of Amistad Dam 1,215 180.08 1,034.92 −10.28 −16.45
7033508 6.7 miles E of Amistad Dam 1,175 160.72 1,014.28 −11.01 −37.09
7122403 25.3 miles NW of Amistad Dam on Pecos River 1,312 199.62 1112.38 −36.55 A +61.01
7140201 3.2 miles NNE of Amistad Dam 1,167 N/A N/A N/A N/A
7140307 2.0 miles NE of Amistad Dam 1,162 N/A N/A N/A N/A

A Change in elevation for 7122403 is from WY2022, as no measurement was made in WY2023.

Figure 5. Line graph showing water levels in four wells are lower than the reservoir water level and generally increase and decrease with the reservoir level. Water levels in two wells are higher than the reservoir and do not fluctuate as much.
Figure 5. Water level elevation in feet above mean sea level (ft amsl) in six groundwater monitoring wells and Amistad Reservoir at Amistad National Recreation Area, 1964–2024. A break in a continuous line indicates missing data.

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Springs

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. 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?). WY2024 springs sampling at Amistad National Recreation Area occurred between 07 April and 11 April 2024. Water persistence is monitored continuously throughout the water year, but in this report, we only present WY2024 persistence data up to the sampling visit date for each spring.

Methods

Chihuahuan 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 the invasive non-native 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. Data are presented only for the primary sampling location within each spring. Each perennial spring is somewhat unique, and Texas has not adopted water quality standards that would apply across the diversity of springs described here. 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.

eDNA Inventory of Rare and Invasive Species and Pathogens

We inventory rare species, invasive species, and pathogens in perennial springs using environmental DNA (eDNA) techniques. In 2023 and 2024, four or more water samples (250 mL/sample) were collected and filtered (0.45 µm) from each spring and then preserved in ethanol prior to DNA extraction and analysis by the Goldberg Lab at Washington State University. Our target organisms for the inventory are American bullfrog (Rana catesbeiana), barred tiger salamander (Ambystoma mavortium), Blanchard’s cricket frog (Acris blanchardi), Mexican blindcat (Prietella phreatophila), red spotted toad (Bufo punctatus), and Rio Grande leopard frog (Rana berlandieri).

Results

Big Satan Canyon Spring

Highlights: The spring orifices were not flowing, and the wetted area was much smaller than in other years. We observed three new invasive plant species (Bermuda grass, common reed, and spiny sowthistle) and one new wetland plant (willow). A goat carcass was floating in the pool.

Big Satan Canyon Spring (Figures 6 and 7) is a rheocrene spring (a spring that emerges into one or more stream channels) located in Big Satan Canyon, a tributary to the Devils River. The spring emerges from multiple orifices created by small fissures in the bedrock-lined canyon and forms an elongated pool that has been measured up to 32.5 m in length and is bounded on three sides by rock. The WY2024 visit occurred on 09 April 2024, and the spring contained water; however, it appeared to be run-off, and there was no active flow from the spring orifices.

Figure 6. A dry riverbed of white bedrock dotted with sparse, grass-like vegetation and low shrubs. There is a small pool of water in the center of the drainage and cliffs along one side.
Figure 6. Overview of Big Satan Canyon Spring and the surrounding landscape at Amistad National Recreation Area, April 2024.

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Figure 7. A pool of water with a greenish hue surrounded by white rock in a drainage lined by white rock banks, with green vegetation growing on the uplands above the drainage.
Figure 7. The pool at Big Satan Canyon Spring in Amistad National Recreation Area, April 2024.

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Site Condition

In WY2024, we rated Big Satan Canyon Spring slightly disturbed by livestock, with goats observed at the site visit and a goat carcass in the water (rated undisturbed to slightly disturbed in the past) and moderately disturbed by drying based on the complete drying of all the previously wetted primary orifices and a reduction of the wetted area to an approximately 6 × 15 m stagnant pool in the deepest part of the channel (rated undisturbed to slightly disturbed in the past; Figure 8). Scat at the spring site indicates wildlife are using the spring. No other natural or human-caused disturbances were observed at Big Satan Canyon Spring in WY2024.

Figure 8. A dry riverbed in a canyon of white bedrock and grey cliffs with grass-like vegetation dotting the edges.
Figure 8. Dry conditions at Big Satan Canyon Spring in WY2024.

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We did not observe the invasive non-native American bullfrog (Rana catesbeiana) at Big Satan Canyon Spring in WY2024. We observed six species of invasive non-native plants: a matrix of yellow bluestem (Bothriochloa ischaemum, scattered patches to a matrix observed in 2018–2023); scattered patches of Bermuda grass (Cynodon dactylon, not previously observed); 1–5 tree tobacco plants (Nicotiana glauca, 1–5 plants to scattered patches observed in 2017–2023); scattered patches of common reed (Phragmites australis, not previously observed); scattered patches of spiny sowthistle (Sonchus asper, not previously observed); and scattered patches of lilac chastetree (Vitex agnus-castus, 1–5 plants observed in 2023).

We observed seven obligate/facultative wetland plants at Big Satan Canyon Spring in WY2024: bluestem (Andropogon sp., a grass observed in 2019–2023); bulrush (Schoenoplectus sp., a sedge observed in 2023); common buttonbush (Cephalanthus occidentalis, a shrub observed in 2023); turkey tangle fogfruit (Phyla nodiflora, a forb observed in 2018–2023); a member of the rush family (Juncaceae, observed in 2018–2023); spikerush (Eleocharis sp., a sedge observed in 2018–2023); and willow (Salix sp., a tree not previously observed).

eDNA Inventory of Rare and Invasive Species and Pathogens

In WY2024, we did not collect water samples from Big Satan Canyon Spring for eDNA analysis. In WY2023, five water samples were collected, and none of the 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 9). The temperature sensor indicated that Big Satan Canyon Spring was wetted (contained water) for all 192 days (100%) measured in WY2024 up to the visit, however all of the spring orifices were dry during the visit. Our wet/dry analysis could be affected by the shade of the canyon walls, potentially leading to false wet indications. In prior water years, the spring was wetted 78.4–100% of the days measured.

Figure 9. Graph indicating that Big Satan Canyon Spring was mostly wetted between spring 2021 and spring 2024, apart from a dry period during summer of 2022. There are missing data during the first half of water year 2023.
Figure 9. Water persistence through 09 April 2024 in Big Satan Canyon Spring, Amistad National Recreation Area. White areas indicate dates before sensors were first deployed or after the WY2024 visit. Black diamonds indicate sensor deployment dates.

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Discharge measurements were last conducted at Big Satan Canyon Spring in WY2017, when discharge was estimated at 12.1 L/min (3.2 gal/min; Table 2). Since then, discharge has not been measurable at the site. We did not collect wetted extent measurements in WY2024 because there was a goat carcass in the pool, which posed a contamination risk. To ensure the safety of field personnel, no in-water data collection was conducted during the WY2024 site visit. Past wetted extent measurements are presented in Table 3 for reference.

Table 2. Discharge data (L/min; mean ± SD) for Big Satan Canyon Spring in water year (WY) 2024 and a range of means from prior years. c.n.s. = could not sample.
Sampling Location WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
002 c.n.s. (12.1) 2017 (1)

Table 3. Average (± SD) width, depth, and length of Big Satan Canyon Spring in water year (WY) 2024 and a mean from a prior year. c.n.s. = could not sample.
Measurement WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
Width (m) c.n.s. (11.4) 2018 (1)
Depth (m) c.n.s. (c.n.s.) 2018 (1)
Length (m) c.n.s. (32.5) 2018 (1)
Water Quality

The crew did not collect water quality or water chemistry measurements in WY2024 for safety reasons related to the goat carcass mentioned above. Past data are summarized in Tables 4 and 5.

Table 4. Core water quality data for Big Satan Canyon Spring in water year (WY) 2024 and a range of values from prior years. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
003 Dissolved oxygen (mg/L) c.n.s. (4.67–5.71) 2018–2023 (4)
003 pH c.n.s. (7.23–7.36) 2017–2023 (5)
003 Specific conductivity (µS/cm) c.n.s. (431.2–463.2) 2018–2023 (4)
003 Temperature (°C) c.n.s. (22.3–23.4) 2017–2023 (7)
003 Total dissolved solids (mg/L) c.n.s. (273–301) 2017–2023 (5)

Table 5. Water chemistry data (mg/L) for Big Satan Canyon Spring in water year (WY) 2024 and a range of values from prior years. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
003 Alkalinity (CaCO3) c.n.s. (190–240) 2017–2023 (3)
003 Calcium (Ca) c.n.s. (64–68) 2017–2023 (3)
003 Chloride (Cl) c.n.s. (0–15) 2017–2023 (3)
003 Magnesium (Mg) c.n.s. (7–15) 2017–2023 (3)
003 Potassium (K) c.n.s. (0.0–1.6) 2017–2023 (3)
003 Sulphate (SO4) c.n.s. (0–2) 2017–2023 (3)

Dead Man’s Canyon Spring

Highlights: The spring contained water, but pools were not overflowing, indicating drier conditions. The temperature sensors indicated the spring was wet all year. We detected Mexican blindcat and Rio Grande leopard frog in the eDNA samples.

Dead Man’s Canyon Spring (Figures 10 and 11) is a hanging garden spring (a complex, multi-habitat spring that emerges along geologic contacts and seeps, drips, or pours onto underlying walls). The spring is situated in Dead Man’s Canyon, a tributary of the Pecos River. Spring water seeps from the cliff face, trickling down the rocks and supporting a robust community of wetland plants clinging to the wall. Hidden grottos hold water and create pools behind the vegetation. The flow from this hanging garden converges with water from two other orifices inside the canyon bottom to form a channel that has extended over 100 m. The WY2024 visit occurred on 10 April 2024, and the spring contained water.

Figure 10. Bright green ferns, mosses, and other wetland plants hanging from a wet bank along the side of a bedrock-lined drainage. Tall, wispy bunches of grass-like plants are scattered along the bank.
Figure 10. The hanging garden at Dead Man’s Canyon Spring in Amistad National Recreation Area, April 2024.

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Figure 11. Depressions in a bedrock-lined drainage lined by bedrock cliffs. One area has thick vegetation hanging from the cliff and growing from the base along the drainage.
Figure 11. Overview of Dead Man’s Canyon Spring and the surrounding landscape at Amistad National Recreation Area, April 2024.

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Site Condition

In WY2024, we rated Dead Man’s Canyon Spring slightly disturbed by contemporary human use based on trash seen around the spring and along the path leading to it (rated undisturbed to slightly disturbed in the past); slightly disturbed by feral animals and wildlife with scat in and around the spring and browsed plants at the site (rated undisturbed to slightly disturbed in the past); and slightly disturbed by drying because previously wet pools that flowed into other pools had dried and were not connected by flow (rated undisturbed to slightly disturbed in the past; Figure 12). No other natural or human-caused disturbances were observed at Dead Man’s Canyon Spring in WY2024.

Figure 12. A person points to a dry spot on the ground next to dense shrubs in contrast with the white limestone rock surroundings.
Figure 12. Dry conditions at Dead Man’s Canyon Spring in WY2024.

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We did not observe the invasive non-native American bullfrog (Rana catesbeiana) at Dead Man’s Canyon Spring in WY2024. We recorded three species of invasive non-native plants: scattered patches of yellow bluestem (Bothriochloa ischaemum, scattered patches observed in 2018–2023); scattered patches of Bermudagrass (Cynodon dactylon, scattered patches observed in 2017–2023); and 1–5 tree tobacco plants (Nicotiana glauca, 1–5 plants observed in 2017–2022).

We observed six obligate/facultative wetland plant species in WY2024: bulrush (Schoenoplectus sp., a sedge observed in 2023); common buttonbush (Cephalanthus occidentalis, a shrub observed in 2019–2023); turkey tangle fogfruit (Phyla nodiflora, a forb observed in 2019); maidenhair fern (Adiantum sp., a fern observed in 2018–2023); mule-fat (Baccharis salicifolia, a shrub observed in 2017–2023); and spikerush (Eleocharis sp., a sedge observed in 2018–2019).

eDNA Inventory of Rare and Invasive Species and Pathogens

In WY2024, six water samples were collected from Dead Man’s Canyon Spring. We detected Mexican blindcat in one sample and Rio Grande leopard frog in five samples. In WY2023, four water samples were collected, and none of the 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 13). The temperature sensor indicated that Dead Man’s Canyon Spring was wetted (contained water) for all 193 days (100%) measured in WY2024 up to the visit. In prior water years, the spring was wetted 54.1–100% of the days measured across entire years.

Figure 13. Area graph indicating that Dead Man’s Canyon Spring was mostly wetted on measured dates between October 2017 and April 2024 except for a dry period during the summer of 2022. There are missing data during the second half of WY2017, the first half of WY2018, and from July 2020 to April 2022.
Figure 13. Water persistence through 10 April 2024 in Dead Man’s Canyon Spring, Amistad National Recreation Area. White areas indicate dates before sensors were first deployed or after the WY2024 visit. Black diamonds indicate sensor deployment dates.

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Discharge was estimated at 1.5 ± 0.1 L/min (0.4 ± 0.03 gal/min), consistent with the historical range of 1.3–14.0 L/min (0.3–3.7 gal/min) but on the lower end of that range at this sampling location where the flow converges below the hanging garden (Table 6). Wetted extent was evaluated using a method for flowing water. The total springbrook length was 35.7 m (117.1 ft), which was comparable with the previously recorded range (measured length of 6.7 m [22.0 ft] to estimated lengths between 200 to 500 m [656–1,640 feet]). In WY2024, width and depth along the springbrook averaged 61.6 cm (24.3 in) and 2.2 cm (0.9 in), respectively. Width and depth were smaller than in any prior years measured (Table 7).

Table 6. Discharge data (L/min; mean ± SD) for Dead Man’s Canyon Spring in water year (WY) 2024 and a range of means from prior years.
Sampling Location WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
007 1.5 ± 0.1 (1.3–14.0) 2017–2023 (5)

Table 7. Length and average (± SD) width and depth of Dead Man’s Canyon Spring (measured within the first 100 m of springbrook length) in water year (WY) 2024 and ranges of length values and width and depth means from prior years.
Measurement WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
Width (cm) 61.6 ± 88.8 (85.8–496.7) 2018–2023 (4)
Depth (cm) 2.2 ± 3.5 (5.2–10.5) 2018–2023 (4)
Length (m) 35.7 (6.7–100.0) 2018–2023 (4)
Water Quality

Core water quality and water chemistry data were not collected at the primary sampling location because there was not enough water to sample at that location. Past data are presented in Tables 8 and 9.

Table 8. Core water quality data for Dead Man’s Canyon Spring in water year (WY) 2024 and a range of values from prior years. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
001 Dissolved oxygen (mg/L) c.n.s. (5.59–12.02) 2017–2023 (5)
001 pH c.n.s. (7.84–8.19) 2017–2023 (5)
001 Specific conductivity (µS/cm) c.n.s. (416.7–450.8) 2017–2023 (5)
001 Temperature (°C) c.n.s. (18.0–22.3) 2017–2023 (7)
001 Total dissolved solids (mg/L) c.n.s. (271–293) 2017–2023 (5)

Table 9. Water chemistry data (mg/L) for Dead Man’s Canyon Spring in water year (WY) 2024 and a range of values from prior years. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
001 Alkalinity (CaCO3) c.n.s. (160–190) 2017–2023 (5)
001 Calcium (Ca) c.n.s. (56–70) 2017–2023 (5)
001 Chloride (Cl) c.n.s. (13–36) 2017–2023 (5)
001 Magnesium (Mg) c.n.s. (12–96) 2017–2023 (5)
001 Potassium (K) c.n.s. (0.8–2.0) 2017–2023 (5)
001 Sulphate (SO4) c.n.s. (3–8) 2017–2023 (5)

Indian Springs Canyon Spring

Highlights: Only one orifice had water and the wetted area of the springbrook was significantly smaller than in the past. There was scattered trash and the site was disturbed by goats.

Indian Springs Canyon Spring (Figures 14 and 15) is a rheocrene spring (a spring that emerges into one or more stream channels). The spring has a strong hydrologic connectivity to the water level of Lake Amistad, and as a result, the emergence location for this spring is highly variable. At WY2018, WY2019, and WY2020 visits, the spring emerged about 500 m upstream of the canyon’s mouth. In WY2022, the spring emerged at the mouth of the canyon, and in WY2023, it emerged in between those locations. Spring characteristics vary depending on emergence location, but the spring typically forms standing, elongated pools or a stream slowly flowing over cobble and bedrock. The springbrook has been over 100 m in length. The WY2024 visit occurred on 11 April 2024, and the spring had water at the mouth of the canyon.

Figure 14. Person pointing to the upstream edge of a stagnant pool of brown water surrounded by a vast area of white bedrock and cobble.
Figure 14. Emergence of Indian Springs Canyon Spring at Amistad National Recreation Area, April 2024.

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Figure 15. Bedrock and dry hillsides surrounding a shallow canyon with a small pool of water at its mouth and a river in the distance.
Figure 15. Overview of the mouth of Indian Springs Canyon Spring and surrounding landscape at Amistad National Recreation Area, April 2024.

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Site Condition

In WY2024, site condition was assessed near the mouth of the canyon. We rated Indian Springs Canyon Spring slightly disturbed by fire, with charred remnants from a past fire (rated undisturbed in the past); moderately disturbed by contemporary human use, with scattered trash at the site (rated undisturbed to moderately disturbed in the past); moderately disturbed by livestock with goat herds, tracks, and droppings in the vicinity (rated undisturbed in the past); and moderately disturbed by drying based on the minimal wetted area and the drying of all but one of the previously flowing orifices (rated undisturbed to highly disturbed in the past; Figure 16). Tracks and scat indicate that wildlife is using the spring. No other natural or human-caused disturbances were observed at Indian Springs Canyon Spring in WY2024.

Figure 16. A dry wash with boulders and exposed bedrock surrounded by green shrubs in front of desert hills.
Figure 16. Dry conditions at Indian Springs Canyon Spring in WY2024.

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As in past years, we did not observe the invasive non-native American bullfrog (Rana catesbeiana) at Indian Springs Canyon Spring in WY2024. We recorded five species of invasive non-native plants: scattered patches of yellow bluestem (Bothriochloa ischaemum, scattered patches observed in 2018–2021); evenly distributed patches of seaside petunia (Calibrachoa parviflora, evenly distributed patches observed in 2023); evenly distributed patches of Bermudagrass (Cynodon dactylon, 1–5 plants to a matrix observed in 2018–2023); scattered patches of tree tobacco (Nicotiana glauca, scattered patches observed in 2022–2023); and scattered patches of lilac chastetree (Vitex agnus-castus, 1–5 plants to a matrix observed in 2017–2023).

We observed one obligate/facultative wetland plant species at the spring: turkey tangle fogfruit (Phyla nodiflora, a forb observed in 2019–2021).

eDNA Inventory of Rare and Invasive Species and Pathogens

In WY2024, seven water samples were collected from Indian Springs Canyon Spring and nearby springs along the Devils River. None of the target organisms were detected. In WY2023, four water samples were collected directly from Indian Springs Canyon Spring, and none of the 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 17). Persistence is monitored at orifice A. The temperature sensor indicated that Indian Springs Canyon Spring was wetted (contained water) for 20 of 194 days (10.3%) measured in WY2024 up to the visit. In prior water years, the spring was wetted 3.6–86.7% of the days measured across entire years.

Figure 17. Area graph indicating that Indian Springs Canyon Spring has exhibited long periods of drying since monitoring began in April 2018, with notable exceptions being mostly wetted periods from April 2019 to February 2020 and during the spring of 2023. There are missing data from fall 2018 to spring 2019 and from spring 2022 to spring 2023.
Figure 17. Water persistence through 11 April 2024 in Indian Springs Canyon Spring, Amistad National Recreation Area. White areas indicate dates before sensors were first deployed or after the WY2024 visit. Black diamonds indicate sensor deployment dates.

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Discharge was not measured in WY2024 at the primary sampling location because there was no measurable surface flow. Past discharge data are not available for this sampling location. Wetted extent was evaluated using a method for flowing water. The total springbrook length was 7.7 m (25.3 ft), which was notably shorter than the previously recorded range (measured length of 27.0 m [88.6 ft] to an estimated length of 100 to 200 m [328–656 ft]). In WY2024, width and depth along the springbrook averaged 101.8 cm (40.1 in) and 4.7 cm (1.9 in), respectively. The springbrook was much narrower than in prior years, while average depth was within the range of values from prior years (Table 10).

Table 10. Length and average (± SD) width and depth of Indian Springs Canyon Spring (measured within the first 100 m of springbrook length) in water year (WY) 2024 and ranges of length values and width and depth means from prior years.
Measurement WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
Width (cm) 101.8 ± 53.9 (179.2–556.5) 2017–2023 (5)
Depth (cm) 4.7 ± 3.3 (3.5–19.6) 2017–2023 (5)
Length (m) 7.7 (27.0–100.0) 2017–2023 (5)
Water Quality

Core water quality (Table 11) and water chemistry (Table 12) data were not collected at the primary sampling location in WY2024 because the sampling location was dry. Past data are presented in the tables.

Table 11. Core water quality data for Indian Springs Canyon Spring in water year (WY) 2024 could not be collected as the sampling location was dry: the range of values from prior years is given. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
008 Dissolved oxygen (mg/L) c.n.s. (5.62) 2023 (1)
008 pH c.n.s. (7.59) 2023 (1)
008 Specific conductivity (µS/cm) c.n.s. (399.1) 2023 (1)
008 Temperature (°C) c.n.s. (23.5) 2023 (1)
008 Total dissolved solids (mg/L) c.n.s. (259) 2023 (1)

Table 12. Water chemistry data (mg/L) for Indian Springs Canyon Spring in water year (WY) 2024 could not be collected as the sampling location was dry: the range of values from prior years is given. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
008 Alkalinity (CaCO3) c.n.s. (150) 2023 (1)
008 Calcium (Ca) c.n.s. (52) 2023 (1)
008 Chloride (Cl) c.n.s. (5) 2023 (1)
008 Magnesium (Mg) c.n.s. (17) 2023 (1)
008 Potassium (K) c.n.s. (1.3) 2023 (1)
008 Sulphate (SO4) c.n.s. (0) 2023 (1)

Mouth of the Pecos Spring

Highlights: The spring had no water when we visited, and plants were visibly stressed from drying. We observed two new invasive plant species: common reed and hedgeparsley.

Mouth of the Pecos Spring (Figures 18 and 19) is a limnocrene spring (a spring that emerges into one or more lentic pools). The spring is located in a side canyon of the Lower Pecos River, just upstream from its confluence with Lake Amistad. When flowing, the spring emerges from two orifices to form small pools surrounded by boulders in the canyon bottom before dispersing into a marshy area populated by cattails. The WY2024 visit occurred on 07 April 2024, and the spring was dry.

Figure 18. Large boulders, rocks and green vegetation in a depression with no surface water in a drainage.
Figure 18. One of the previously wet pools at Mouth of the Pecos Spring at Amistad National Recreation Area, April 2024.

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Figure 19. Reddish brown plants dot a dry riverbed next to a tall black and tan cliff face. Taller green vegetation is growing along the base of the cliff.
Figure 19. Cross-view of the canyon just downstream of Mouth of the Pecos Spring at Amistad National Recreation Area, April 2024.

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Site Condition

In WY2024, we rated Mouth of the Pecos Spring slightly disturbed by contemporary human use because of trash from the nearby day-use area (rated slightly disturbed in the past); slightly disturbed by wildlife based on a porcupine carcass, javelina scat, and deer shed at the spring (rated undisturbed to slightly disturbed in the past); and highly disturbed by drying because no orifices were flowing and wetland vegetation showed signs of stress (rated undisturbed to highly disturbed in the past; Figure 20). No other natural or human-caused disturbances were observed at Mouth of the Pecos Spring in WY2024.

Figure 20. Grey Boulders and rocks in a dry drainage surrounded by green shrubs with sunlight streaming through.
Figure 20. Dry conditions at Mouth of the Pecos Spring in WY2024.

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We did not observe the invasive non-native American bullfrog (Rana catesbeiana) at Mouth of the Pecos Spring in WY2024. We recorded eight species of invasive non-native plants at the spring: a matrix of giant reed (Arundo donax, evenly distributed patches to a matrix observed in 2018–2023); scattered patches of Bermudagrass (Cynodon dactylon, scattered patches to matrix observed in 2017–2023); 1–5 tree tobacco plants (Nicotiana glauca, 1–5 plants to scattered patches observed in 2017–2021); evenly distributed patches of common reed (Phragmites australis, not previously observed); scattered patches of annual rabbitsfoot grass (Polypogon monspeliensis, 1–5 plants observed in 2018); scattered patches of sowthistle (Sonchus sp., 1–5 plants observed in 2021); scattered patches of tamarisk (Tamarix sp., 1–5 plants to scattered patches observed in 2018–2023); and scattered patches of spreading hedgeparsley (Torilis arvensis, not previously observed).

We observed five obligate/facultative wetland plant species at the spring in WY2024: giant reed (Arundo donax, a grass observed in 2018–2023); mule-fat (Baccharis salicifolia, a shrub observed in 2017–2023); annual rabbit’s foot grass (Polypogon monspeliensis, a grass observed in 2018); tamarisk (Tamarix sp., a tree/shrub observed in 2018–2023); and willow (Salix sp., a tree previously observed in 2019–2021).

eDNA Inventory of Rare and Invasive Species and Pathogens

No water samples were collected in WY2023 or WY2024 for eDNA analysis because the spring was dry during both visits.

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 21). The temperature sensor indicated that Mouth of the Pecos Spring was wetted (contained water) for 174 of 190 days (91.6%) measured in WY2024 up to the visit. Our wet/dry analysis could be affected by the shade of the canyon walls, potentially leading to false wet indications. In prior water years, the spring was wetted 56.4–100% of the days measured across entire years.

Figure 21. Graph indicating that Mouth of the Pecos Spring was continuously wet from the beginning of WY2017 to mid-spring of 2021. The spring and summer of 2021–2023 were intermittently dry. There are missing data during the winter and spring months of 2017 and 2023.
Figure 21. Water persistence through 07 April 2024 in Mouth of the Pecos Spring, Amistad National Recreation Area. White areas indicate dates before sensors were first deployed or after the WY2024 visit. Black diamonds indicate sensor deployment dates.

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Discharge was not measured in WY2024 at the primary sampling location because the spring was dry at the time of the visit. Discharge estimates are available for one prior year, 2019, when it was estimated at 23.1 L/min (6.1 gal/min; Table 13). The standing water method for wetted extent was not used in WY2024 because the spring was dry, but wetted extent data for 2018–2019 are shown in Table 14.

Table 13. Discharge data (L/min; mean ± SD) for Mouth of the Pecos Spring in water year (WY) 2024 could not be collected as the spring was dry: the range of means from prior years is given. c.n.s. = could not sample.
Sampling Location WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
006 c.n.s. (23.1) 2019 (1)

Table 14. Average (± SD) width, depth, and length of Mouth of the Pecos Spring in water year (WY) 2024 could not be collected as the spring was dry: the range of means from prior years is given. c.n.s. = could not sample.
Measurement WY2024 Mean
(Range of Prior Means)		 Prior Years Measured
(# of Visits with Measurements)
Width (m) c.n.s. (3.80–4.17) 2018–2019 (2)
Depth (cm) c.n.s. (43.7–45.0) 2018–2019 (2)
Length (m) c.n.s. (2.58–5.30) 2018–2019 (2)
Water Quality

Core water quality (Table 15) and water chemistry (Table 16) data were not collected in WY2024 because the spring was dry. We report previous (2018–2019) values in the tables.

Table 15. Core water quality data for Mouth of the Pecos Spring in water year (WY) 2024 and a range of values from prior years. Water quality measurements were not taken in WY2024 because the spring was dry. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
005 Dissolved oxygen (mg/L) c.n.s. (2.79–3.77) 2018–2019 (2)
005 pH c.n.s. (7.35–7.40) 2018–2019 (2)
005 Specific conductivity (µS/cm) c.n.s. (553) 2018–2019 (2)
005 Temperature (°C) c.n.s. (22.7–23.6) 2018–2019 (4)
005 Total dissolved solids (mg/L) c.n.s. (357.5) 2018–2019 (2)

Table 16. Water chemistry data (mg/L) for Mouth of the Pecos Spring in water year (WY) 2024 and a range of values from prior years. Water chemistry measurements were not taken in WY2024 because the spring was dry. c.n.s. = could not sample.
Sampling Location Parameter WY2024 Value
(Range of Prior Values)		 Prior Years Measured
(# of Measurements)
005 Alkalinity (CaCO3) c.n.s. (210–235) 2018–2019 (2)
005 Calcium (Ca) c.n.s. (54–56) 2018–2019 (2)
005 Chloride (Cl) c.n.s. (15–24) 2018–2019 (2)
005 Magnesium (Mg) c.n.s. (18–20) 2018–2019 (2)
005 Potassium (K) c.n.s. (1.5–1.9) 2018–2019 (2)
005 Sulphate (SO4) c.n.s. (29–31) 2018–2019 (2)

Past Reports

Previous annual reports can be found at the following links:

Literature Cited

Author Information

Kara Raymond 1  ORCID.org logo  https://orcid.org/0009-0004-7265-5919

Susan Singley 2

Tani Hubbard 3  ORCID.org logo  https://orcid.org/0009-0009-8777-4773

1 National Park Service
Southern Arizona Office
12661 E. Broadway Blvd.
Tucson, AZ 85748

2 National Park Service
Chihuahuan Desert Network
New Mexico State University, MSC 3ARP
3655 Research Dr., Genesis Building D
Las Cruces, NM 88003

3 Northern Rockies Conservation Cooperative and National Park Service
12661 E. Broadway Blvd.
Tucson, AZ 85748

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