July 2026
There is growing interest in reusing water for potable and non-potable applications exemplified by the U.S. Environmental Protection Agency (EPA)’s Water Reuse Action Plan. Recently, the EPA launched the Water Reuse Action Plan (WRAP) 2.0, building on the success of its original action plan. ToxStrategies has experience developing pragmatic, data-driven approaches to safety assessments of water for reuse.
Oil and gas operations can generate significant volumes of water, commonly referred to as produced water. Produced water consists of both naturally occurring water present in geologic formations where oil and gas originate and flowback water, which can include fluids introduced into the well during hydraulic fracturing. While produced water is typically highly saline and may contain a variety of chemical constituents, its potential as an alternative water source is receiving increasing attention, particularly in water-stressed regions. The growing interest in produced water reuse, reflected in EPA’s Water Reuse Action Plan, which includes evaluating risks associated with off-field reuse of oil and gas produced water. Such reuse is being advanced at the state level by consortia in Colorado, New Mexico, and Texas. The ToxStrategies case study highlights how ToxStrategies applied a rigorous, risk-based framework to evaluate whether groundwater potentially impacted by produced water could be safely used for crop irrigation.
Challenge
A groundwater source with potential value for agricultural irrigation was suspected to have been historically affected by produced water from nearby oil and gas operations. Because crop irrigation water could potentially be blended with the impacted groundwater, stakeholders needed a scientifically defensible assessment to determine whether using the produced water for irrigation would be protective of human health.
Risk-Based Approach
ToxStrategies developed a comprehensive conceptual exposure model for irrigated fruit and nut tree agriculture. The model incorporated site-specific environmental conditions, including precipitation, runoff, and irrigation practices, as well as crop-specific evapotranspiration rates and chemical-specific processes affecting contaminant fate in soil. The assessment also estimated chemical transfer from groundwater into edible crop fractions and evaluated potential cancer and non-cancer health risks for both adults and children consuming the harvested crops.
The evaluation followed a tiered risk assessment process. First, site-specific groundwater monitoring data were compared with relevant health-based screening criteria to identify chemicals of potential concern. A screening-level assessment was then conducted using conservative exposure assumptions designed to overestimate potential risks. Constituents that exceeded target risk thresholds advanced to a refined deterministic assessment that estimated both central tendency and upper-bound exposures using more realistic, site-specific assumptions.
Chemicals selected for evaluation included metals, organic compounds, and radionuclides. The assessment also incorporated a comprehensive uncertainty analysis to evaluate the influence of key exposure assumptions, environmental fate parameters, and toxicity criteria on risk estimates.
Technical Execution
Critical components of the project involved an extensive literature review, data evaluation, and parameter development. ToxStrategies compiled and organized chemical-specific information necessary for characterizing contaminant behavior in the terrestrial environment, including soil partitioning, degradation rates, plant uptake factors, and bioavailability. The team also assembled site- and scenario-specific inputs, such as local rainfall patterns, irrigation conditions, and crop consumption rates to support robust exposure modeling.
Results and Impact
This project demonstrated a scientifically rigorous approach for evaluating the suitability of groundwater potentially impacted by oil and gas produced water for agricultural reuse. By combining site-specific data, advanced exposure modeling, and tiered human health risk assessment methods, ToxStrategies provided stakeholders with a defensible basis for crop irrigation decision making.
As interest in water reuse continues to expand, this work illustrates how complex environmental and human health risks can be evaluated to support sustainable water management strategies. ToxStrategies remains at the forefront of developing and applying innovative risk assessment approaches that inform client decisions and contribute to broader scientific and regulatory discussions on water reuse. (https://toxstrategies.com/services/risk-assessment/).
Contact us at info@toxstrategies.com to discuss how we can help you with water reuse.