Continuous Water Quality MRG: I-25 2010

Healthy aquatic ecosystems in arid land rivers have become increasingly
important as climate change and swelling populations place greater strain upon
already limited water resources. Little is known about the spatio-temporal patterns
in the water quality of the Middle Rio Grande (MRG) which runs through major urban
centers in arid New Mexico, and now provides drinking water for Albuquerque, NM. The
rapidly urbanizing character of the MRG, such as urban storm drains and waste water
treatment plants places numerous stressors linked to water quality on the biota of
the river. The purpose of this monitoring and research program is to assess temporal
and spatial trends for five water quality parameters (temperature, pH, conductivity,
turbidity, and dissolved oxygen) and determine stream metabolism in the MRG using
continuous, near real-time, data along the 60.3 river kilometers (37.5 miles) of the
Albuquerque reach of the MRG. Monitoring was conducted at 4 research sites in the
Greater Albuquerque area using multi-parameter water quality meters. Temperature
trends displayed the expected yearly summer highs averaging 25 º - 30 º C and winter
lows averaging ~0 º C. Conductivity measurements ranged widely and were responsive
to local monsoon storms as well as fire debris-related discharge pulses originating
in northern NM after the Las Conchas fire. Dissolved oxygen showed an inverse trend
to temperature with summer lows and winter high and responded to 1) local storm
pulses with frequently hypoxic DO sags and 2) fire-related discharge pulses with
sustained hypoxia and anoxia. Turbidity data was highly variable and frequently
above the range of the sensors. However, it was possible to determine that some
turbidity spikes followed by gradual depletions were related to both local storm and
upstream fire-related events. Data collected during this project demonstrate that WQ
in the MRG is spatially and temporally variable and responsive to episodic
occurrences such as monsoon storms and fire-related discharge events. These results
indicate that multiple years of continued data collection are required to provide an
accurate assessment of the response of MRG water quality to inter-annual climate
variability, episodic events and resulting changes in river flow.