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# The Elwha's insects returned in number before their river community recovered
- URL: https://intelligence.wildlandseco.com/2026-10-22-elwha-dam-removal-invertebrate-recovery/
- Published: 2026-10-22T14:21:54.000Z
- Updated: 2026-10-22T14:21:54.000Z
- Description: Nine years of monitoring after two large dam removals show that the rebound in insect abundance and the recovery of community composition are not the same milestone.
- Author: Benjamin Worlund
- Tags: dam removal, river recovery, sediment, macroinvertebrates, Water, Wildlife, restoration, Connectivity, Monitoring, #ecological-intelligence, #brief-2026-10-22, #priority-read, #peer-reviewed, #geo-north-america, #edition-lead

Evidence

Peer-reviewed

Geography

Elwha River, Washington, United States

System

River / dam removal / sediment disturbance

## WHAT THE EVIDENCE SAYS

Following removal of the Elwha and Glines Canyon dams, more than 20 million tonnes of reservoir sediment moved downstream as passage reopened to more than 90% of the watershed. Across five river reaches and nine years of observations, benthic invertebrate density fell as much as 95% during active removal, then returned near baseline within roughly three years of peak sediment transport. Taxa richness and community composition, notably some caddisflies and longer-lived groups, remained altered after that interval.

## WHY IT MATTERS / OUR READ

The ecological signature of a restoration project can contain immediate disturbance, recovery in one metric and prolonged change in another. Restoration success criteria should distinguish connectivity, organism numbers, sensitive taxa and community composition; the years after construction are part of the intervention, not an optional follow-up.

## CAVEATS / UNCERTAINTY

Observational before-during-after monitoring was conducted in one very large dam-removal system, with fish recolonization, sediment and habitat succession interacting. A numerical rebound does not prove all functions or populations are restored; these outcomes do not imply dams should remain.

## SOURCE

Frontiers in Ecology and Evolution — Morley et al. (2026)  
[View original evidence ↗](https://doi.org/10.3389/fevo.2026.1914975?ref=intelligence.wildlandseco.com)

From the Morning Brief · 2026-10-22

[Read the full Morning Brief →](https://intelligence.wildlandseco.com/morning-brief-2026-10-22/)