---
name: environmental-impact-assessment
description: Use when asked to plan, write, or review an environmental impact assessment — a systematic evaluation of the likely environmental effects of a proposed project or policy before it proceeds, often required by law for larger projects — distinct from a [[sustainability-report]], which discloses an organization's ongoing performance rather than a single project's predicted impact.
---

# Environmental Impact Assessment

An environmental impact assessment (EIA) systematically evaluates the
likely environmental effects of a proposed project or policy before
it goes ahead. Larger projects — infrastructure, mining, major
development — are often legally required to complete one before
approval, and the assessment's findings typically shape what
conditions get attached to that approval.

## Key components

- **Baseline conditions** — the state of air, water, soil, ecology,
  noise levels, and other relevant factors documented *before* the
  project starts, so later change has something to be measured
  against.
- **Identification of significant impacts across categories** —
  systematically working through air quality, water resources,
  ecology and biodiversity, noise, traffic, and any other category
  relevant to the specific project, rather than only the most obvious
  one.
- **Proposed mitigation measures for each significant impact** —
  concrete actions that reduce, avoid, or offset each impact
  identified, not general statements of intent.
- **A monitoring plan for after the project is underway** — how
  impacts will actually be tracked once construction or operation
  begins, not just what was predicted in advance during the
  assessment phase.
- **Alternatives considered** — including a no-action alternative,
  showing the assessment weighed options rather than justifying a
  decision already made.

## Why an undocumented baseline undermines everything that follows

If the conditions before a project started were never measured, no one
can later show whether an observed change — a drop in a fish
population, a rise in noise complaints, a shift in air quality — was
actually caused by the project or would have happened anyway from
unrelated factors. The baseline is what every later claim, in either
direction, gets compared against. Skipping it doesn't just weaken the
assessment on paper; it removes the ability to ever settle a dispute
about the project's real effects, favorable or unfavorable, once it's
operating.

## Common pitfalls

- **Baseline conditions not documented before work starts** — so any
  post-project claim about impact, made by the developer or by
  critics, can't be verified either way.
- **Mitigation measures proposed on paper but never actually
  implemented or checked** — an assessment that lists mitigations as a
  condition of approval is only as good as the follow-through; an
  unchecked mitigation plan is functionally no mitigation plan.
- **Assessment treated as a one-time approval hurdle** — once the
  project is approved, the ongoing monitoring the assessment committed
  to is dropped, leaving no record of whether predicted impacts
  actually matched what happened.
- **Impacts assessed in isolation from cumulative effects** — a
  project's impact evaluated on its own without accounting for other
  nearby projects or existing pressures on the same resource.
- **Significant categories skipped because they're less visible** —
  noise or groundwater effects, for instance, getting less attention
  than the most visually obvious impact even when they matter as much
  or more.

## Learn more

- [[sustainability-report]] for the related but distinct discipline of
  disclosing an organization's ongoing environmental performance
  rather than a single project's predicted impact.
- [[policy-brief]] for summarizing an assessment's findings into a
  short, decision-oriented document for whoever has to act on it.