Bali's Controversial Uluwatu Seawall Project Preserves Historic Culture. But at What Cost?

 

 

View this post on Instagram

 

A post shared by Nic von Rupp (@nicvonrupp)

The project drew global attention in September of 2024 as video of excavators knocking massive piles of dirt and rocks off the cliffs to create the seawall’s base went global on social media. While critics are not insensitive to the importance of protecting the heritage site, they’ve raised concerns about the environmental impact the Uluwatu seawall project will have on the surrounding marine ecosystem. Surfers have also raised concerns about the impact on popular surf breaks, as well as the surf-based economy of the small coastal town.

According to the Bali Sun, the risk of temple collapse was great enough to list the project under an emergency designation, allowing it to skip otherwise-required steps, including an environmental impact assessment and public comment period. Though the Badung Regency Government Office claims the development is legal and above board, the Bali Attorney General’s Office announced onn October 7 an investigation into whether Uluwatu seawall project developers violated any construction or permitting requirements. If violations are found, the project could be temporarily or permanently halted.

What impact do seawalls have on marine ecosystems?

Seawalls and barrier walls have long been controversial, especially those like the one underway in Uluwatu, which is planned to support a paved highway. Construction of seawalls involves dumping large quantities of dirt and debris into the ocean. The disruption can effect water circulation and patterns, which can lead to increases in ocean temperature as the as the warmer coastal waters will exchange less frequently with cooler, deeper waters. Increased ocean temperatures lead to coral bleaching, one of the most pressing concerns happening in the world’s oceans today.

It’s long been known that coral reefs are key to healthy oceans, and as construction debris enters the ocean, the reefs under the cliffs will likely be smothered, blocking sunlight needed for photosynthesis. That will likely lead to a loss of most of the reef’s corals, which will diminish the region’s marine biodiversity, as reefs are vital habitat for fish and other marine species. Species that visit the reef will likely be stressed by reduced water clarity and the associated reduction in food sources, straining the balance of the local food web and potentially reducing the marine ecosystem’s overall health and resilience.

Seawalls can also alter the natural flow of sediment along the coast, which could make erosion worse in other nearby areas, or impact the sand distribution needed for Bali’s beach ecosystems. That means the effects of the new Uluwatu seawall construction could extend beyond Uluwatu, impacting the health and economies of beach towns and environments around the island.

Key marine species near the Uluwatu Seawall site

Under the surface at Uluwatu Cliffs is a thriving marine ecosystem, home to dozens of endangered, rare, and key species critical to maintaining healthy oceans. That includes the hawksbill and green sea turtles, listed as critically endangered and endangered, respectively, due to threats like habitat loss and pollution — both of which are likely to increase when the seawall is completed. Sea turtles rely on coral reefs for foraging, as they feed on sponges and other invertebrates. Reducing available food hurts not just current members of a species, but also future generations, as fewer mating and nesting habitats will be available.

Other critically important species around Uluwatu’s reefs include including bumphead parrotfish and napoleon wrasse, both classified as endangered due to overfishing and habitat loss. Rare species of colorful, micro-sized nudibranchs (or sea slugs) and mantis shrimp also live on the reefs, and several endangered mega fauna live in Bali’s oceans. That includes the great hammerhead shark, listed as critically endangered on the IUCN Red List of Threatened Species, and reef and oceanic manta rays, considered vulnerable and endangered, respectively.

Seawalls are a controversial solution

Critics of the Uluwatu seawall project question the choice to fortify the temple with a seawall, as some past seawall projects around the globe have well-documented negative impacts.

The Galveston, TX, seawall

After a devastating 1900 hurricane, a seawall was built in Galveston, a barrier island on along Texas’ gulf coast. Today, it’s a 17-foot-tall concrete barrier that stretches for 10 miles, designed to protect the city from hurricanes and severe storms. Over the last decades, it’s been shown that the massive scale of the project altered natural wave patterns, leading to erosion on adjacent beaches and prompting ongoing, costly rebuilding efforts to mitigate the damage. While the seawall has likely saved lives, the growing size of hurricanes means more and more could be large enough to send water above the walls, as seen with Hurricane Ike in 2008 and Hurricane Nicholas in 2021.

The Hilo, HI seawall

The Hilo Bay seawall, constructed in the early 1900s, was built to shield the bay from coastal flooding and create calmer water for traffic moving in and out. While effective in calming swells, the seawall has also disrupted the natural flow of sediment along the coastline, leading to increased sediment build up in some areas and significantly increased erosion in others. Scientific observations and long-term monitoring of water quality and reef health showed a measured decline in coral reef health and size, as well as reduced water circulation, leading to dwindling fish populations — something people are concerned may also happen with the Uluwatu seawall project. Growing public concern about the impact of seawalls in the state has lead state officials to consider tighter laws and regulations around the construction of future seawall projects.

The Gold Coast seawall, Australia

The seawall along Australia’s Gold Coast, which is about 10 miles long, has been a source of controversy. Peer-reviewed studies in the Journal of Coastal Research highlighted several ecological concerns related to the seawall, including fewer sand deposits, leading to a reduction in habitat for beach-dwelling species, including crabs and seabirds, and a loss of turtle nesting sites. Those concerns, along with concerns about other issues related to increased storm surges and declining ocean health, are guiding factors for the region’s multi-million dollar ongoing Coastal Adaptation Plan. Around the country’s Great Barrier Reef, many scuba diving companies have taken to running coral replacement programs to help replace coral lost to human development.