Chiricahua National Monument's Climate, Groundwater and Springs: Water Year 2021

Climate and water shape ecosystems, especially in dry country, and knowing how climate, groundwater and surface water are changing is key to judging the condition of a park's natural — and often cultural — resources. At Chiricahua National Monument, scientists of the NPS Sonoran Desert Network track vital signs year after year, like a doctor with a patient, to catch problems early. Results are reported by water year: water year 2021 ran from October 2020 to September 2021.

A storm over Chiricahua National Monument. NPS/M. Cahill.

Figure 1. The monitored weather station and groundwater wells at Chiricahua National Monument. NPS.

Climate

Weather is conditions right now; climate is the pattern over seasons to years, and the main driver of ecological processes. Data come from a Remote Automated Weather Station (Chiricahua, Arizona #021409) running since 1995, via the Climate Analyzer.

Outside the monsoon, rain was near or below average every month; the biggest daily fall was 1.54 in on August 13, 2021. The reconnaissance drought index — the ratio of precipitation to potential evapotranspiration (the water that would evaporate or be used by plants if supply were unlimited) — shows 2021 was somewhat drier than average.

Figure 2. Monthly precipitation and mean maximum and minimum temperatures, water year 2021. Data: climateanalyzer.org.

Figure 3. Reconnaissance drought index, water years 1996–2021. Data: climateanalyzer.org.

Groundwater

Groundwater is one of the Southwest's most critical resources, for drinking, irrigation, and the rivers, streams and springs it sustains. The monument has three wells: Campground-1 and Headquarters, measured monthly by staff, and Faraway Ranch, monitored continuously since 2016 by the Arizona Department of Water Resources.

• Levels were lower in all three wells than the year before.
• Campground-1 measurements stopped early in the year over safety concerns (to resume once a new well house is built), so its average doesn't cover the whole year, and pumping at a nearby well may affect it.
• Faraway Ranch hit its lowest level, 17.59 ft below ground, in July 2021, then rebounded quickly after monsoon storms.
• Overall levels have been stable, varying only 5.42–8.49 ft over the monitoring period, with seasonal swings from runoff in Bonita Creek.

Figure 4. Depth to water at the three wells, with monthly precipitation, water years 2007–2021. NPS.

Springs

Springs, seeps and tinajas (small rock pools) are rare biodiversity hotspots in dry lands, linking groundwater and surface water. The network asks mainly how long a spring holds water and how much. Its monitoring covers site characterization (every five years), site condition (disturbance rated 1–4, from undisturbed to highly disturbed, plus wetland plants and invasive bullfrogs, crayfish and plants), water quantity (persistence from temperature loggers — water damps daily swings — plus discharge and wetted extent), and water quality.

Garfield Spring — a flowing (rheocrene) spring on a north-facing slope. Visited April 20, 2021: wet all 176 days measured. Discharge 0.6 liters a minute, against 0.3–0.5 in earlier years; the brook ran only 25 m (82 ft), well short of the 35.9–37.5 m of 2017–2019. Chloride (10 mg/L) was higher than before (3–5). A trail, wildlife, and a new wildlife-camera study caused slight disturbance; sedges grew there and no invasives were seen.

Figure 5. Garfield Spring's orifice (left) and the springbrook below it (right), April 2021. NPS photos.

Figure 6. Water persistence in Garfield Spring. NPS.

Newton Cave Seep — at the foot of an east-facing cliff under an overhang. Visited April 19: shrunk to a five-centimeter patch of saturated soil — "highly disturbed" by drying, worse than in past years, and the usually greener oaks nearby looked like the surrounding hillside. With no surface water, discharge, extent and quality couldn't be measured; loggers read it wet 174 of 174 days, likely because of the overhang.

Figure 7. Newton Cave Seep, April 2021. NPS photo.

Figure 8. Water persistence in Newton Cave Seep. NPS.

Shake Spring — a flowing spring in a west-facing drainage of Bonita Canyon, rising under a car-sized boulder. Visited April 19: wet all 201 days; discharge 7.5 liters a minute, within past range, but the brook was only 31 m (102 ft), about 30–40% of past lengths. Magnesium and sulfate were much lower, and alkalinity much higher, than ever before; dissolved oxygen slightly lower. The spring box and concrete pad left it moderately disturbed; a few common mullein plants were the only non-native; horsetail, monkeyflower, sedges, sycamore and willow grew there.

Figure 9. Shake Spring, April 2021. NPS photo.

Figure 10. Water persistence in Shake Spring. NPS.

Silver Spur Spring — a flowing spring in the channel of lower Bonita Canyon. Visited April 20: wet all 202 days, but with no flowing water to measure discharge; the brook ran 68 m (223 ft), within past range. Total dissolved solids and chloride were just below past ranges, and dissolved oxygen was low (hypoxic) as in some past years, perhaps from decaying leaves. A trail leads right to it; flatsedge, horsetail, sedge and sycamore grew there, with no invasives. (No sampling took place in 2020 because of COVID-19.)

Figure 11. Silver Spur Spring (left) and its springbrook (right), April 2021. NPS photos.

Figure 12. Water persistence in Silver Spur Spring. NPS.

Sources

Based on "Climate and Water Monitoring at Chiricahua National Monument: Water Year 2021," National Park Service, prepared by Kara Raymond (Southern Arizona Office) and Andy Hubbard, Cheryl McIntyre and Laura Palacios (Sonoran Desert Network); a work of the United States government in the public domain.