Middle Rio Grande Regional Water Plan

Runoff, flooding, and debris flows following catastrophic wildfire are also important
nonpoint source issues. The USGS New Mexico Water Science Center has developed a
pre-wildfire assessment approach that can be used to decrease the hazard of post-wildfire
debris flows and protect vital watersheds. An evaluation of the Sandia and Manzano
mountains was published in 2014 (Tillery et al., 2014).
In addition to surface water issues, a primary water quality concern in the planning region is
groundwater contamination due to septic tanks. Because septic systems are generally spread out
over rural areas, they are considered a nonpoint source. Collectively, septic tanks and other onsite
domestic wastewater disposal systems constitute the single largest known source of
groundwater contamination in New Mexico (NMWQCC, 2002), with many of these occurrences
in areas with shallow water tables, such as those located along the Rio Grande. In areas with
shallow water tables or in karst terrain, septic system discharges can percolate rapidly to the
underlying aquifer and increase concentrations of (NMWQCC, 2002):
Total dissolved solids (TDS)
Iron, manganese, and sulfides (anoxic contamination)
Nitrate
Potentially toxic organic chemicals
Bacteria, viruses, and parasites (microbiological contamination)
Bernalillo County has implemented a septic tank ordinance, but they remain a water quality
concern, particularly in the East Mountain area and in areas with shallow water tables, such as
Corrales.
5.5 Administrative Water Supply
The Handbook describes a common technical approach (referred to there as a platform) for
analyzing the water supply in all 16 water planning regions in a consistent manner. As discussed
in the Handbook (NMISC, 2013), many methods can be used to account for supply and demand,
but some of the tools for implementing these analyses are available for only parts of New
Mexico, and resources for developing them for all regions are not currently available. Therefore,
the State has developed a simple method that can be used consistently across all regions to assess
supply and demand for planning purposes. The use of this consistent method will facilitate
efficient development of a statewide overview of the balance between supply and demand in
both normal and drought conditions, so that the State can move forward with planning and
funding water projects and programs that will address the regions’ and State’s pressing water
issues.
The method to estimate the available supply, referred to as the administrative water supply in the
Handbook, is based on withdrawals of water as reported in the New Mexico Water Use by
Middle Rio Grande Regional Water Plan 2017 141