Brackish and Saline Groundwater in New Mexico
Total Page：16
File Type：pdf, Size：1020Kb
summer 2015 BRACKISH AND SALINE GROUNDWATER IN NEW MEXICO New Mexico meets its ever-growing need located more than 2,500 feet below ground kept of the fresh water/salt water interface for water through both surface and ground- surface. This deep water is characterized when water-supply wells were drilled; the water resources. The supply of surface water differently because shallower water is con- drillers seeking fresh water would plug the is largely dependent upon precipitation, and sidered to be “righted,” and has potential hole if the water became too salty. The oil its availability is therefore subject to periods for beneficial use, regardless of salinity. and gas industry also drilled through both of drought. Shallow, fresh groundwater This rule is used to protect known fresh fresh and brackish aquifers––however, the resources supplement the state’s water needs, water supplies, so that they can be defined fresh and brackish water aquifers did not but many of these resources usually contain economi- are being used far faster than WATER TYPE TOTAL DISSOLVED SOLIDS COMMENT cally viable oil and gas they are being replenished, (TDS) IN MILLIGRAMS/LITER) deposits, so records of the and are therefore finite. We Fresh Less than 500 Typical fresh range brackish water occurrence, know that there are deeper, depth, and quality were largely untapped groundwater Brackish 1,000 to 10,000 As defined by USGS not kept or were not resources, but generally these Saline 10,000 to 35,000 Seawater is ~35,000 publicly available. are too salty to drink or to Recently, the USGS Brine 35,000 to 200,000 use for irrigation without began to update the treatment. Nonetheless, they Oil and gas co- Derived from oil and gas national inventory of produced waters ~500 to over 200,000 production provide a potential alternative brackish water resources, source of groundwater, and Fully salt saturated Greater than 250,000 Found in some oil focusing efforts on the are of increasing interest to and gas produced groundwater within 3,000 the state, particularly as our waters and deep saline feet below land surface, reservoirs evolving technologies are with total dissolved solids providing ways for us to use Types of water classified by salinity range as defined by total dissolved solids (TDS) less than 10,000 mg/L them. in milligrams/liter (mg/L). and with the potential for Groundwater is water “useable” water yield. This that is found in pore spaces of rock and in a basin and protected. Even though a work is projected to take about 4 years, and sediment below the land surface. We know water right per se is not assigned to this it will be most useful to address brackish that much of our shallow groundwater in deeper, saltier water, the NMOSE must water availability at regional or basin scales. New Mexico is fresh in quality, and is a be notified when someone plans to drill a In New Mexico, there are multiple good source of drinking water and water well into these zones, in order to manage datasets describing fresh, brackish, and for irrigation. However, in many places we the basin water supplies and to prevent saline water resources, however, they are encounter saltier water when we drill wells impingement on nearby fresh water. not compiled together to help address the into groundwater basins. How much salty state’s current water needs. Much of the water is there, and where can we find it? Status of New Mexico’s Brackish pertinent data for New Mexico’s brackish Can we use it during times of drought, or Water Resources and saline water resources are held within in remote locations that do not have rivers historic water reports, geologic research or lakes? Or in applications where fresh Some of the first national-scale studies on reports, or with oil and gas producer’s water is not required? Will we damage the brackish water resources were performed in records. In 2003–2004, a brackish water environment, especially our existing fresh the late 1950s and early 1960s by the U.S. task force was formed, aiming to character- water resources, if we try to use it? Geological Survey (USGS). These studies ize all of New Mexico’s brackish water In New Mexico, the Office of the State have been cited repeatedly since then, resources. However, work quickly ended Engineer (NMOSE) characterizes water as because most subsequent water exploration due to the lack of funding. Currently, being “deep non-potable water” when TDS has been focused primarily on fresh water, the New Mexico Bureau of Geology and is greater than 1,000 mg/L and the water is not salty water. Records were often not Mineral Resources, New Mexico Tech’s Published by the New Mexico Bureau of Geology and Mineral Resources • A Division of New Mexico Tech units, or sometimes it is as brine concentrate), and to transport the result of evaporation. the treated water to the point of use. The extraction of deep brackish waters is much Brackish Water as a more expensive than extraction of shal- Drought Solution lower fresh water. Pumping costs are much With advanced planning higher, and aquifer permeability is much and the necessary fund- lower in deep aquifers. Multiple wells may ing, we can use brackish be needed to extract the water. water as a supplement to Capital costs to install a brackish water fresh water in times of treatment facility can be between $10 drought or other shortage million and $95 million, depending upon situations. This use can system size. Operations and maintenance improve the lifetime of our can cost $4 million to $6 million per year. fresh water supplies. Financing, permitting, and energy sources Because brackish water must be acquired. This adds up to about will usually need to be $500 per acre-foot of water delivered Graph of salinity and depth in New Mexico wells. More data exist for freshwater and shallow locations. (Sources: NMBGMR, USGS, desalinated, this means above the costs for fresh water delivery. In NMED). we need to invest in ways contrast, the cost for water from a municipal to extract (via pumping), drinking water treatment facility is about Petroleum Recovery Research Center, and transport (via pipelines or trucks), and $300 per acre-foot delivered from a fresh the New Mexico Water Resources Research treat the water (e.g., using membrane surface source. The electricity requirement Institute, along with other institutions in methods like reverse osmosis, or thermal for reverse-osmosis desalination ranges from New Mexico, are gathering information methods like distillation). In 2010, of the 3–12 kWh/m3 with electricity costs reach- to create a database of all water ing 50% or more of the total cost resources in New Mexico, includ- to desalinate. In sum, desalination ing fresh, brackish, and saline is effective but not necessarily the inventories, as well as produced least expensive or most energy- water quality, quantities, and loca- efficient method to improve water tions. Work recently completed supply reliability. by the New Mexico Bureau of Geology and Mineral Resources describes the fresh and brackish Environmental Impacts of water aquifers in the San Juan Brackish Water Use Basin region (Kelley et al., 2014). Brackish water in deep, confined The most recently compiled aquifers is, in most cases, not a estimates of the quantity of brack- renewable resource. If we extract ish groundwater in New Mexico this water, eventually the supply come from sources such as Feth will be depleted. Land surface (1970), Huff (2004), and Hale et subsidence from groundwater al., (1965). Currently, there is no extraction in the Central Valley reference that gives adequate or of California has reached up to 30 complete volume estimations of feet. That water cannot be replaced brackish water for the state. in aquifer storage because of permanent collapse in the aquifer Locations of Brackish pore spaces. Water Resources in New Water extraction from shallow Mexico brackish aquifers should not deplete or contaminate fresh Extensive work over the last 50 water that may be interconnected. years has cataloged basins in the Approximate locations of brackish water basins of interest. Impingement can occur if we state containing fresh and brackish withdraw brackish groundwater water. Significant basins include that is interconnected to fresh water the Albuquerque Basin, San by geologic faults or other means. Pumping 314 desalination plants in the U.S., 95% Juan Basin, Roswell Basin, Capitan Reef can entrain and mix the two waters if were inland. Municipal plants were 67% Aquifer, Estancia Basin, Mesilla Basin, and there is not a sufficient barrier between of the total desalination plant capacity, Tularosa Basin. In addition, some rivers, the aquifers. Barriers are composed of followed by industrial plants (18% of total) streams, and springs or seeps in the state low-permeability rocks or sediments that (Mickley, 2010). Common municipal are salty, such as stretches of the Pecos prevent water flow. Permitting by the applications of desalination include the River and the Rio Grande. This is mostly NMOSE is implemented to help examine production of water for drinking, reuse, the result of saline or brackish groundwater and prevent this mixing and impinge- and recharge. We also need to dispose of discharging to the surface, surface water ment. Sufficient hydrologic studies of the the resulting salty waste stream (known interaction with the underlying geologic boundaries of a brackish groundwater new mexico earth matters 2 summer 2015 source are necessary prior to extraction; a and capacity of the disposal formation; the The Special Case of Oil and Gas clear understanding of nearby fresh water formation also is in a more remote area Produced Water resources also is important.