Industrial, agricultural and municipal pollution has caused enormous damage to riparian ecosystems
- By Steven Crook / Contributing Reporter
In Taiwan, as in other countries that have experienced rapid industrialization, a downside of development has been the degradation of its rivers.
To some extent, this was the result of people turning their backs on the streams that watered their ancestors’ fields and the creeks where their grandmothers washed clothes. Once tap water was available and road bridges crossed major waterways, urban dwellers had no reason to think about rivers—unless they needed a place to dump waste that couldn’t be burned.
Industrial, agricultural, and municipal pollution has caused enormous damage to riparian ecosystems, or riverbanks. The heavy use of ammonium fertilizers has been a factor in the decline of the Taiwan freshwater mussel (Corbicula fluminea formosa). This species was once so abundant that when country folk talked about killing two birds with one stone, they would say in Hoklo (the language also known as Taiwanese) “to collect mussels while washing your pants in the stream.”
Photo: Steven Crook
How polluted are Taiwan’s waterways? According to the Environmental Protection Administration’s (EPA) Water Quality Protection Division, of the country’s 2,934 km of streams and rivers, 68.1 percent were unpolluted in 2020. In the same year, 9.3 percent were lightly polluted, 19.3 percent were moderately polluted, and 3.3 percent were heavily polluted. EPA data shows a very slight improvement between 2007 and 2019.
An Oct. 2018 paper in the academic journal Water examined data from monitoring stations for 14 major rivers and concluded that pollution was nearly ubiquitous between 2002 and 2016. Lead concentrations exceeding the EPA standard limit were found in the Dongshan (冬山), Jhuoshuei (濁水), and Sinhuwei (新虎尾) rivers. Copper levels were exceeded in the Dahan (大漢), Laojie (老街), and Erren (二仁) rivers. All 14 rivers were contaminated with manganese.
March 14 will be the 25th International Day of Action for Rivers. Once again, this cross-border expression of solidarity and concern will go unmarked in Taiwan.
Photo: Steven Crook
Even so, many Taiwanese are expressing concern about the state of local waterways. Among them is Liao Kuei-hsien (廖桂賢), an associate professor at the Graduate School of Urban Planning at National Taipei University and convener of the Taiwan River Network (台灣河溪網), an NGO that works to promote the protection and restoration of river health. .
“CRUSHED WATER” TREATMENT
According to Liao, pollution is one of the two major challenges facing Taiwan’s rivers.
Photo: Steven Crook
“Black water” (wastewater from toilets) is almost always treated before being discharged, often into septic tanks. However, she points out, what is called “gray water” is often released untreated into rivers and streams. Because it comes from bathrooms and washing machines, gray water usually contains traces of human waste.
Liao applauds the efforts made by many local governments to increase the percentage of gray water that is treated. However, she says, more work needs to be done to increase the rate of domestic wastewater treatment.
Data from the Construction and Planning Agency of the Ministry of the Interior shows that wastewater treatment rates at the beginning of this year in the six special municipalities ranged from 94 percent (in New Taipei) to 59 percent (in Tainan). Several local governments reported rates below 50 percent, with the lowest rates in Chiayi County (21.5 percent) and Taitung County (17 percent).
Photo: Steven Crook
Sewerage systems are not as visible as bridges or cultural sites, and “elected politicians tend to ignore this issue because it’s not sexy,” says Liao. “The central government needs to provide greater incentives for local governments to do this, and voters need to be better educated to understand the importance of wastewater treatment,” she adds.
More toxic pollution escapes from industrial areas and feedlots (buildings where animals or birds are raised). Wastewater from those places should be treated before being released, but as Liao points out, illegal discharges still occur from time to time, turning rivers bizarre colors.
“Current fines are not a deterrent,” she explains. “In most waterways in Taiwan, we see the dominance of non-native, pollution-tolerant species such as tilapia, striped snakehead, and Amazon catfish,” says Liao, describing the latter as “extremely invasive.”
“THREE SMOOTH SIDED” ENGINEERING.
Native species are struggling to survive not just because of pollution, but also because “morphological modification” – human-induced changes to the shape and direction of river channels – is undermining the health of local waterways.
“In the name of flood control or soil and water conservation, it’s very common to see streams or smaller rivers completely covered in concrete,” she says. According to Liao, this form of river engineering—known locally as sanmianguang (三面光, “three smooth sides”)—“basically destroys the entire ecosystem of the river.”
The waters, bed, and banks of an unpolluted and unmodified river are likely to host amphibians such as frogs, crustaceans and mollusks, fish, and insects, as well as various plants and microorganisms. These in turn support populations of birds and reptiles.
Due to increased environmental awareness among engineers and the public, authorities are less likely to convert sections of river into completely concreted channels.
The Public Works Commission recognizes the drawbacks of “three-sided” and “two-sided” engineering. Its website points out that concrete channels do not necessarily protect nearby communities from flooding because “all natural river features are removed, so the velocity of floodwater increases.”
Additionally, they are said to be preventing groundwater recharge, exacerbating Taiwan’s water shortage.
“Streams that escape being completely covered in concrete often have their natural banks converted into covers, usually concrete or riprap. This means eliminating the entire riparian zone – the interface of land and water – which is very important to the river ecosystem,” says Liao.
Furthermore, she explains, modifying riverbanks in this way disrupts the connection between waterways and their floodplains. Very often, there is a decrease in habitat heterogeneity and, as a result, a reduction in overall biodiversity.
Horizontal structures, such as check dams built to slow water speed and reduce erosion, “seriously impede upstream-downstream connections, affecting the migration of fish and other creatures up and down the river,” says Liao.
Dams have likely been a factor in the decline of landlocked Formosan salmon. Such barriers prevent fish that are washed downstream during typhoons from returning to cooler waters where they might survive, and divide populations into isolated groups, increasing the risk of inbreeding. As part of efforts to save the salmon from extinction, a handful of check dams in Shei-Pa National Park (雪霸國家公園) have been demolished.
FLOOD SAFETY
Liao says that Taiwan’s larger rivers are relatively less modified, meaning that while they are contained by levees, they have wider corridors to ensure that floodwaters are carried out to sea. Floodplain areas outside the levees, however, are often heavily modified, with natural vegetation removed. Around Taipei City, many floodplains have been converted into parking lots and sports fields.
“To address the problem of morphological change, the root cause – the ingrained belief that rivers need to be designed or controlled for flood safety – needs to be addressed. However, this is very difficult,” says Liao.
Liao says flood engineering is an unsustainable approach to flood safety. Increasing flood resilience is much more important in the face of extreme rainfall events. In the long term, she adds, we will need to shift the flood mitigation paradigm from flood control to flood resilience.
RIVER RESTORATION MOVEMENT
In the medium term, Liao calls for a nationwide river restoration movement that would “restore the health of river ecosystems so that they can provide more ecosystem services. Where necessary, we should free streams and rivers from hard structures, such as levees and structures that impede flow. To control flooding and erosion, we can implement ecological engineering methods and nature-based solutions instead of hard engineering.”
She says that while the Ministry of Economic Affairs’ Water Resources Agency (WRA) and local government units claim to pay attention to ecological issues, “often their understanding of ecology is superficial.”
The Facebook group “Urban Rivers and Streams” (城鄉河溪論壇) highlighted a recent case where a government agency botched a so-called “river improvement project.”
During the modification of part of Dahu Stream (大湖) in Yuanshan Township (員山) of Yilan County by the First River Management Office of the WRA, a belt of riverside vegetation that should have been preserved was eradicated.
It appears that conservation measures were not clarified in the contract and related diagrams; changes to the plan were not checked and confirmed with stakeholders; ecological inspection data after August last year was left blank; and records relating to the public participation phase may have been falsified.
The Dahu Creek project (budget: $40.7 million) is just a small part of what has become a major industry. NT$183 million has been earmarked for the reconstruction of the middle and lower reaches of Sanye Creek (三爺) in Tainan. On Jan. 20 this year, United Daily News reported that work is about to begin on a section of Hutou Creek (虎頭), also in Tainan, the first phase estimated to cost NT$400 million.
A new approach to Taiwan’s waterways is possible, but only if the country’s leaders are willing to upset a few apple carts.
Steven Crook, the author or co-author of four books about Taiwan, has been following environmental issues since arriving in the country in 1991. He drives a hybrid and carries his own chopsticks. The views expressed here are his own.
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