Status of climate and water resources at Gila Cliff Dwellings National Monument: Water year 2016

Gwilliam, Evan; Hubbard, J.; Palacios, Laura; Raymond, Kara

Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosys-tem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, streamflow, and water quality is central to assessing the condition of park biota and key cultural resources. This report combines data collected on climate, groundwater, and surface water at Gila Cliff Dwellings National Monument (NM) to provide an integrated look at climate and water conditions during water year 2016 (October 2015–September 2016). Although 2016 was the hottest year on record globally (NASA 2017), local air-temperature patterns at Gila Cliff Dwellings NM were more mixed. Maximum air temperatures in Feb-ruary, March, June, and July were well above normal. Annual precipitation was 113% of normal, with the largest increases occurring in November, April, and September. Increased rainfall and mixed air temperatures reduced the reconnaissance drought index relative to recent years, indicating a degree of recovery from the drought of the early 2000s. The available stream-gauge data at Gila Cliff Dwellings NM did not meet QA/QC require-ments during water year 2016. Annual discharge for the region was interpreted from data from USGS gauge 09430500 in Gila, New Mexico, 40 kilometers downstream of the monu-ment. Discharge was generally within the normal range, with high-flow events in late January, late July, and September. None of these flow events, if they did occur at the West Fork of the Gila River index site, overflowed the river banks. The flow event in late July was captured on the multi-parameter datalogger at the index site, but these data indicated a stream-elevation increase of less than five inches, and other parameters (temperature, specific conductivity, pH) rapidly returned to median values after this event. There were 236 discrete analyses of water samples collected from the West Fork Gila River index site in water year 2016. Of these samples, 89 were associated with New Mexico surface water criteria. Of those 89 samples, there were five exceedances of state standards, meaning that 94% of samples were compliant with state standards. There were exceedances for E. coli, turbidity, and total aluminum (chronic fish and wildlife). The stream was flowing at a higher rate during several sampling visits, and an elevated level of total suspended sediments indi-cates that the aluminum exceedance was likely the result of precipitation flushing sediment into the stream. Higher concentrations of aluminum have been detected in the past; they are not the result of human activity. Macroinvertebrates were collected to provide data for compliance with the New Mexico biological standards. In water year 2016, the index reach scored a 60.78 on the New Mexico integrated biological index, putting it in the “good” category. Habitat metrics collected with the macroinvertebrate samples indicated a system that continues to recover from the impact of fires in water years 2011–2012.

Status of climate and water resources at Gila Cliff Dwellings National Monument: Water year 2016

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