Pokhara’s shrinking Phewa Lake

The once pristine Phewa Lake that used to reflect the majestic Annapurnas and Machhapuchre is shrinking, depriving Pokhara of its main attraction.

Siltation from the river and streams feeding into it have reduced its area, the lake has become an urban garbage and sewage dumping site, and real estate speculators have encroached on the banks. Geologists have calculated that the lake accumulates more than 142,000 tonnes of sediment every year.

Tourism-driven urbanisation and pollution mean that the famous lake is now devoid of its aquatic life, and there has been a visible decline in the number of migratory birds nesting here. Indicator insects such as fireflies, dragonflies and butterflies that depend on clean water sources have also started to vanish.

But more worryingly, this important wetland in Pokhara and a major Ramsar site is shrinking rapidly due to increased sediment load due to haphazard building and road construction on the slopes above the lake.

Unusually heavy monsoon downpours last month in the Phewa watershed washed down silt into the lake, turning the water turbid brown, and submerging paddy fields in the river delta.

In 1957, Phewa Lake was 1,119 hectares, but a survey earlier this year by Gandaki Province showed it had shrunk to 572 hectares. “At this rate, Phewa taal will be reduced to a mere pond in the next two decades,” says local Pame resident Shankar Aryal.

Phewa Lake was originally stretched as far west as Chankhapur, and boats would go up to Pame to transport goods. Traders from as far as Parbat district used these boats to bring their produce to lakeside, transfer them to mules bound for Pokhara’s market. But with the extension of the road to Pame in 1994, people started using vehicles for transportation.

What used to be a boat dock is now a swamp and has been filling up with sediment for the past two years. The land mafia has encroached further on the lake by using tipper trucks to dump soil on the lake to sell for new residential plots.

“Wetlands are the earth's kidneys, they filter water at the source, which then flows into the lake. Their deterioration and disappearance do not bode well for our water bodies and causes the lake to shrink further,” explains conservationist Raju Acharya.

Irregular precipitation patterns due to the impact of the global climate crisis have added to the problem. Pokhara receives the most rain in Nepal even at normal times. Earlier this month, it recorded 210mm of rain (10% of the annual average) in just 24 hours, bringing down huge quantities of sediment and raising the lake bed in the shallow shore near Chankhapur.

On one hand, the rise in water level allowed for invasive species such as water hyacinth found on the mouth of the lake to spread further and clog up the fish cages, resulting in financial losses for local businesses.

But heavy, incessant rains also bring in large amounts of deposits. Landslides in the catchment area flow through the Khare River and into the Harpan River, the main source of Phewa lake. This in turn raises the bed of the lake, which like Pokhara’s other lakes, were formed after a catastrophic flood 800 years ago on the Seti River after a landslide dam burst upstream, covering the valley in debris 100m deep.

Much of what used to be Phewa Lake has already been turned into paddy fields as the lake shrinks. Pokhara Mayor Man Bahadur GC has vowed to clean up the lake and turn it back to its original condition. But his words have not been turned into action yet.

Pokhara Metropolis with the Gandaki Province built cofferdams and siltation ponds last year to prevent soil and pebbles from the Harpan, Andheri River, Lauruk and Betayani Khola flowing in and then filling up the lake.

But the check dam on Harpan Khola is already filled with sand and boulders from last month’s floods.

A total of four dams were approved, their construction began in December 2019 and by July 2020 they were completed at Rs281.6 million. But even as they were under construction, locals and experts alike claimed that they were not strong enough to check the siltation.

“The water flow is too strong and the dams are too shallow for them to be of much use,” says local resident Bishu Dahal. “But the project people didn’t even listen to the experts, so it has just been a waste of money.”

How big is Phewa Lake? Depends whom you ask.

Phewa Lake has a close to a century-long history of survey data from national and international experts to calculate its exact area:

1924: British Survey of India 3.46 sq km

1957: Survey of India 4.39 sq km

1960: Nepal-India Support Mission 10.35 sq km

1974: First Fort measurement 4.43 sq km

1980: Nepal-UNDP Survey 5.80 sq km

1994: IUCN Report 4.49 sq km

2000: District Development Committee, Kaski 4.2. sq km

2006: Pokhara Valley Urban Development Committee 5.03 sq km

2011: Bishowoprakash Lamichanne Report 6.5 sq km

2014: Ministry of Land Reform 5.07 sq km

2020: Pokhara Metropolis 5.08 sq km

2020: Gandaki Province Report 5.726 sq km