Water development projects — including borehole drilling — do not exist in an environmental vacuum. Extracting groundwater changes subsurface conditions, affects ecosystems, and can have cascading effects on other water users and natural systems. The Environmental Impact Assessment (EIA) is the formal process by which these effects are identified, evaluated, and managed before the project begins.
The Purpose of an EIA
An EIA serves three interconnected purposes: it protects the environment by identifying and mitigating harmful impacts before they occur; it protects the project by ensuring that environmental risks are understood and managed; and it satisfies legal requirements, since most jurisdictions require some form of environmental review before permitting groundwater abstraction above certain thresholds.
A well-conducted EIA is not a bureaucratic obstacle — it is a risk management tool. Projects that proceed without adequate environmental review face regulatory enforcement, reputational damage, and the practical consequences of environmental problems they could have avoided.
Scoping: Defining What Matters
The first step in an EIA is scoping — determining which environmental issues are relevant to the specific project and location. Not every EIA needs to examine every possible impact. A small community borehole in a rural area with no sensitive habitats nearby requires a much lighter-touch assessment than a large-scale irrigation abstraction in a water-stressed catchment.
Scoping typically involves consultation with the relevant environmental and water authorities to agree on the terms of reference for the assessment.
Key Impact Areas
Groundwater depletion and aquifer stress — the most direct impact of abstraction. The EIA must assess whether the proposed abstraction rate is sustainable given the aquifer's recharge rate and existing demands. In stressed aquifers, additional abstraction may cause water table decline, reducing yields in neighbouring boreholes and drying up springs and baseflows.
Impacts on surface water — in hydraulically connected systems, groundwater abstraction can reduce flows in rivers, streams, and wetlands. This is particularly significant in ecologically sensitive areas where surface water bodies support important habitats or downstream users.
Impacts on dependent ecosystems — groundwater-dependent ecosystems (GDEs) include riparian vegetation, wetlands, springs, and certain terrestrial habitats whose root systems access the water table. Lowering the water table can stress or kill GDE vegetation, with cascading effects on biodiversity.
Naturally occurring contaminants — drilling into certain geological formations can mobilise arsenic, fluoride, naturally occurring radioactive materials (NORM), or other substances that were previously immobile. The EIA should identify geological risk zones and specify water quality testing requirements.
Drilling waste and fluid management — drilling produces drill cuttings, spent drilling fluids, and wastewater. Improper disposal can contaminate surface water and soil. The EIA should specify disposal protocols.
Construction impacts — noise, dust, heavy vehicle movements, and temporary land disturbance during drilling can affect local communities and habitats. These are typically short-term but should be acknowledged and mitigated.
Mitigation and Monitoring
For each identified impact, the EIA proposes mitigation measures — design changes, operational restrictions, or management practices that reduce the impact to an acceptable level. These are compiled into an Environmental Management Plan (EMP), which becomes a binding component of the project's regulatory approval.
Monitoring requirements — specifying what will be measured, how often, and by whom — are typically stipulated in the EMP and may be a condition of the abstraction licence. Groundwater level monitoring in observation boreholes, periodic water quality testing, and baseflow gauging in nearby streams are common requirements.