EBTAG Annual Workshop and Field Trip
October 12-13, 2017

¹New Mexico Bureau of Geology, 801 Leroy pl, Socorro, NM, 87801, ethan.mamer@nmt.edu

In 2015, the New Mexico Bureau of Geology published a hydrogeologic investigation on the groundwater-fed springs and wetlands found at La Cienega, in the southern Española basin (Johnson, et al., 2016). The report describes how the groundwater in this region is highly susceptible to regional influences such as pumping, drought, and land use changes. As a follow up to this research, a community-funded groundwater monitoring network was implemented around La Cienega, Santa Fe County, New Mexico. Groundwater level monitoring provides an essential tool in groundwater management. The data are publicly available for development or calibration of groundwater models, and can help with protection of groundwater resources. Measurements of changing groundwater levels also directly reflect changes in groundwater storage.

There are 34 wells in the current groundwater monitoring network that is made up of two groups; biannual water level measurements, and long-term (10 year) repeat monitoring. Seven of the wells have also been instrumented with pressure transducers that continuously monitor changes in groundwater levels every 12 hours. The wells that have 10 years of data show water level fluctuations ranging from -6.1 to 10.84 ft over the 10 year period. The median change over the 10 year period, however, is -0.5 ft, showing a general declining trend. The biannual measurements are taken in April and October and are intended to reflect the local seasonal highs and lows of the water table. Almost all of the wells measured biannually are highest in April, just prior to the onset of the growing season. In the late spring, as plants and trees begin to send up new growth, water levels decline rapidly. By October, water levels are at their lowest just prior to the end of the growing season. As vegetation in the area goes dormant in the winter, water levels recover. The median seasonal fluctuation is 0.6 ft. This is consistent with seasonal fluctuations driven by changes in evapotranspiration.

Monitoring groundwater level changes provides an essential tool in groundwater management, development of groundwater models, and protection of groundwater resources. As our dependence on groundwater increases, it is crucial to monitor groundwater to identify declining trends early. Should problems arise, the existence of long-term monitoring data is an invaluable resource that cannot be replicated.

References:

1. Johnson P.S.; Koning, D.J.; Timmons, S.S.; Felix, B., 2016, Geology and hydrology of groundwater-fed springs and wetlands at LaCienega, Santa Fe County, New Mexico, New Mexico Bureau of Geology Mineral Resources, Bulletin, v. 161, pp. 1-92.