Climate, Groundwater and Springs in Southeast Arizona's Parks, Water Year 2019

The National Park Service's Sonoran Desert Network tracks "vital signs" — key measurements repeated year after year, like a doctor tracking a patient's pulse — to warn park managers of problems early enough to act. In the Southeast Arizona group of parks, those vital signs include climate, weather, groundwater and springs, reported together because water depends so closely on climate.

This summary covers water year 2019 (October 2018 through September 2019) at Chiricahua National Monument, Coronado National Memorial and Fort Bowie National Historic Site.

Apache Spring, Fort Bowie National Historic Site (NPS).

How dry is dry?

An aridity index compares long-term average precipitation with potential evapotranspiration — the water that evaporation and plants would remove if water were unlimited — and is used worldwide to classify climates. Chiricahua and Coronado are semiarid, and Fort Bowie likely is too.

Aridity index and elevation of selected southwestern parks (NPS).

Climate

Eight weather stations at high and low elevations cover the three parks: two NOAA Cooperative Observer Program stations, a remote automated weather station, three Davis stations and two U.S. Department of Agriculture rain gauges. (Fort Bowie's station was missing 275 days of data, so its results weren't reported.)

• Precipitation at Chiricahua and Coronado was about normal for the year compared with 1981–2010. Fall and winter were wetter than usual; the summer monsoon was weaker than normal, but storms linked to Hurricane Lorena brought extra rain in September.
• At Chiricahua, October got more than three times its normal rain and November was extremely dry; a very dry June led into the weak monsoon, and September was twice as wet as normal.
• A five-year moving average showed both parks in a minor multiyear rainfall deficit relative to the 30-year average.
• At Chiricahua, average monthly highs were generally cooler than normal and lows warmer; Coronado's temperatures varied more. A drought index showed Chiricahua slightly wetter than normal.

Monthly precipitation at Chiricahua National Monument in WY2019 compared with normals (NPS).

Groundwater

Groundwater supplies drinking water, irrigates crops and feeds streams and springs across the Southwest. The network monitors 10 wells: three at Chiricahua, six at Coronado and one at Fort Bowie.

• Compared with 2018, average levels rose at Fort Bowie and at two of three Chiricahua wells; the third dipped slightly.
• At Coronado, levels fell in five of six wells; the sixth rose slightly.
• Over the long term, Chiricahua's levels have been fairly stable since 2007, varying with the seasons, likely because of water lost to plants and recharge from runoff in Bonita Creek. Fort Bowie's well has also been stable since 2004, apart from temporary drops from routine pumping.

"+" means the water level rose; "−" means it fell.

Measuring depth to water at Coronado National Memorial (NPS).

Springs

Springs, seeps and tinajas are small, rare biodiversity hotspots in dry lands and the main meeting point of groundwater and surface water. Climate change — hotter air, faster evaporation, harsher droughts, more extreme storms and possibly less winter and spring rain — could shrink them or dry them out.

In 2019, crews monitored nine springs: four at Chiricahua, three at Coronado and two at Fort Bowie.

• Most showed little disturbance. Human disturbance included flow changes from dams, berms or spring boxes; natural disturbance included game trails, scat and signs of flooding.
• Each spring had 0–6 wetland plant types and 0–3 invasive species. Six non-native plants turned up across the springs: common mullein, spiny sowthistle, common sowthistle, Lehmann lovegrass, rabbitsfoot grass and red brome.
• All nine likely had surface water for at least part of the year; at the seven with working sensors, water was present most of the year. Flow at eight sites ranged from under 1 to 16.5 liters a minute, and baseline water-quality data were collected at all nine.

Water presence at the monitored springs during WY2019 (NPS).

Sources

• National Park Service, Sonoran Desert Network: "Climate and Water Monitoring at Chiricahua National Monument, Coronado National Memorial, and Fort Bowie National Historic Site, Water Year 2019," summarizing Raymond K, Palacios L, Hubbard JA, McIntyre CL, Gwilliam EL, Status of Climate and Water Resources … Water Year 2019 (2022). The article says four of Coronado's six wells have risen and only two have fallen since their first records, but its table shows three falling (including ACA-2), so no count is given here.