Technical Report

Middle Rio Grande Riparian Groundwater Monitoring June 2019-May 2020

URL: https://webapps.usgs.gov/mrgescp/documents/Caplan-et-al_2021_MRG-Riparian-Groundwater-Monitoring-June-2019-May-2020.pdf

Date: 2021/03/02

Author(s): Caplan T., Bunting L., Widener W., McKenna C.

Publication: Prepared for U.S. Army Corps of Engineers. Prepared by GeoSystems Analysis, Inc., 159 p.

Abstract:

The Albuquerque District of the U.S. Army Corps of Engineers (USACE) has invested considerable resources over the past two decades in improving habitat along the Albuquerque Reach of the Middle Rio Grande (MRG). This work has included improving the surface and groundwater connection between the river and floodplain to support diverse riparian-wetland habitats and the species that rely on them for meeting life-cycle requirements. Part of the USACE’s focus has involved designing and implementing a long-term monitoring program focused on tracking alluvial groundwater conditions across the MRG bosque, particularly across the Albuquerque Reach where various habitat restoration efforts have been implemented.

GeoSystems Analysis, Inc. (GSA) has been under contract by the USACE since 2012 to manage the groundwater monitoring network established by the USACE in 2009. Monitoring reports have been developed annually or bi-annually since 2012 to summarize monitoring results and provide updates regarding the groundwater monitoring network. Network management has involved installing and instrumenting new monitoring wells, conducting monthly monitoring of all uninstrumented wells, quarterly monitoring of instrumented wells, maintaining and calibrating pressure transducers (PTs), and performing annual database management and reporting.

All riparian groundwater monitoring wells addressed in this and all previous reports are located within the Albuquerque reach of the MRG bosque from the Interstate 25 (I-25) Bridge crossing near Isleta Pueblo extending approximately 22-miles upstream to the northern boundary of the Village of Corrales. This current report provides groundwater monitoring methods and results for the June 1, 2019 through May 18, 2020 monitoring period. Automated monitoring data from the uncontracted February 2017 – May 2018 period is included in monthly summary figures, where available. Recommendations are also provided for ways to improve and/or apply the information from the monitoring program.

It is apparent from the monitoring results that alluvial groundwater levels in the Rio Grande bosque respond to changes in river discharge (elevation) rates and extended duration during the snowmelt runoff of 2019 (through mid-July). Based upon the magnitude of the change in groundwater level relative to an associated change in the river discharge, some wells are more hydrologically connected to the river than other wells. Wells located on elevated floodplain terraces are not as connected to surface water inputs from pulse flows or overbank flooding. Conversely, wells located within constructed habitat features such as willow swales or bankline terraces have shallow groundwater (typically less than 3 feet below ground surface), which fluctuates greatly in response to changes in river discharge. Sustained river discharges of greater than 3,000 cfs starting April 23, 2019 and continuing through July 17, 2019 was sufficient to elevate groundwater above the ground surface in many constructed (excavated) habitat features (EHFs) that did not experience flooding in previous years despite similar discharge levels (e.g., 4c swale, GSA 2017, GSA 2019). The elevated groundwater levels in 2019 were likely due to the sustained snowmelt discharge and associated floodplain soil saturation compared to the similar magnitude, but abbreviated duration flood pulse in 2017 (GSA 2018). Recommendations include continuing to conduct PT calibrations as needed, re-surveying well casing heights following large and prolonged flood pulses, adjusting hang lengths to assure data is obtained when groundwater levels are at their deepest, and utilizing groundwater elevation data to calibrate/validate reach-wide riparian groundwater models and to support habitat restoration planning and management.