FULBRIGHT LETTER-6 Water: Phewa Lake

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Dear friends: To satisfy my curiosity and interest in water, I researched literature on Phewa Lake (Photos 1). I found some physical data but little water quality data. Phewa Lake (Fewa Lake or Phewa Tal) is the second largest lake and a major tourist area in Nepal.1-4 I found it interesting that the lake was enlarged (nearly doubled the water level) by damming it for the purposes of irrigation and power generation.3 The lake extends about 4 km northwest to southeast, about 2 km at its widest.3 The lake covers approximately 4.43 km2 (1.7 mi2) area with an average depth of 8.6 m (28 ft). Maximum water depth is 22.8 m (75 ft) and maximum water capacity is about 46,000,000 m3 (37,000 acre·ft).1 The watershed area is 122.53 km2; of which 44.32% is covered by forests, less than 40% is by agricultural land, and about 5% is urban area.2

Photos 1: Phewa Lake, Lakeside, Pokhara, Nepal (Photos by Sato, January –April, 2012

Phewa Lake, Pokhara, Nepal (http://maps.google.com; accessed 03/25/2012)

FULBRIGHT LETTER-6 Water: Phewa Lake

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The primary feeder to Phewa Lake is Harpan Khola (“Khola” means smaller river as compared to “Nadi” which means larger river). Harpan Khola discharges water and sediments to the north side of the lake (Photos 2 & 3). Phirke Khola carries water, sewage and trash from the upstream city, and drains in the lake. In addition, Seti Canal and Bulanudi Khola, also discharge sediments and urban trash to the lake. Based on a time series map analysis, there has been more than a 50% reduction of lake area within 50 years.4 Needless to say, Phewa Lake is in serious trouble.

Lake water is usedfor generation of hydroelectricity, agriculture, fishery, recreation (Photos 4 & 5), as well as for domestic uses, such as bathing and laundry.4

Photo 2: Major inlet area of Phewa Lake: the view from the nearby mountain shows a loss of the lake area due to sediment deposition (Photo by R. Sato, 1/21/2012).

Photo 3: Major inlet area of Phewa Lake: the view from paraglide shows a loss of the lake area due to sediment deposition (Photo by Sato, 2/4/2012).

Photo 5: Little fishermen in Phewa Lake, Pokhara (Photo by Sato, March 25, 2012)

Photos 4: Boating in Phewa Lake (Photo by Sato, February-March, 2012)

FULBRIGHT LETTER-6 Water: Phewa Lake

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There are a number of large and small point sources of pollutants along the lakeside (Photos 6 & 7). The large sewrage conduits are continuous sources of pollutants (trash and sewage) and small conduits/pipes are intermittent sources. Sewage has generally a grayish color and forms a plume in the lake.

Photos 6: Large continuous, point source of pollutants found along the lakeside (Photo by Sato,

January-April, 2012).

Photos 7: Small, intermittent point sources of pollutants found along the lakeside (Photo by Sato,

March-April, 2012).

FULBRIGHT LETTER-6 Water: Phewa Lake

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Throughout a day, Phewa Lake brings local inhabitants to its shoreline. Local people washing clothes along the lakeside is a common sight, and offers an exotic scene to travelers (Photos 8). The laundry activities, however, create soap/detergent plumes, causing contamination and eutrophication of the lake. (“Eutrophication” means “too much nutrients” which can cause an excessive algal growth, resulting in oxygen depletion in water.)

Photos 8: Local people washing clothes in Phewa Lake (Photo taken by Sato, January 2012).

FULBRIGHT LETTER-6 Water: Phewa Lake

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Phewa Lake is also used by local people for bathing. Men put soap all over their bodies, then jump into the lake to rinse their bodies (Photos 9). Women also bathe but in a feminin (quiet) way, so they are usually unnoticed (Photos 10).

Other sources of pollution are agricultural and hotel/restaurant activities near the lakeside (Photo 11).

Photos 9: Men bathing in Phewa Lake and a plume of soap (Photo taken by Sato, January 2012).

Photos 10: Women bathing and laundrying in Phewa Lake (left), and a plume of soap (right) (Photo taken by Sato, January 2012)

Photo 11: Agricultural activity (left) and restaurant (right) near the lakeside (Photo by Sato, April

2012)

FULBRIGHT LETTER-6 Water: Phewa Lake

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Near the agricultural lands and restaurants established along the east side of the lake, a large construction project is in progress (Photos 12). It appears that they are constructing a rock/concrete bank to protect the lake shoreline from soil erosion. This project may also provide locals easier access to waterr to do laundry and bathing. In my opinion, this extensive shoreline modification could do more harm than good by destroying wildlife habitats and spoiling spectacular natural views.

Urban and agricultural runoff, wastewater discharges, washing of clothes, and bathing all contribute to water contamination. Water pollution is evidenced by thick scum layers near the Barahi temple boating area (Photos 13).

Overgrowth of aquatic plants indicates eutrophication (Photo 14). Phewa Lake was classified as oligotrophic (very clean) in the 1970’s, mesotrophic (so so) in the 1980’s, and became eutrophic (polluted) in the 1990’s. 4

Photos 13: Scum in Phewa Lake, Jetter to Barahi Temple (left); Fishermen washing fishnets near a plume of scum (right), Lake Side, Pokhara (Photo by Sato, March 24, 2012)

Photo 14: Macrophyte

in Phewa Lake, Pokhara,

Nepal (Photo by Sato,

February-April, 2012)

Photo 12: Lakeshore bank construction project, east side of Phewa Lake, Pokhara, Nepal (Photo by Sato March-April 2012)

FULBRIGHT LETTER-6 Water: Phewa Lake

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The dam and bypass channel, located at the southeast end of Phewa Lake, are the major outlets of the lake (Photo 15). These areas are also popular with local people for laundry, bathing, and recreational activities (Photos 16 & 17).

An average time for water to stay in the lake is about 100 days; however, all the water in the lake is replaced and replenished by fresh water a few times a year during the rainy season. This must be the reason why this lake still survives despite the large pollutant inputs to the lake. The high inflow rates during the wet season, however, carry large amounts of sediment, which rapidly reduce the capacity of Phewa Lake. Appendix: “Phewa Lake” behind the scene

Photo 15: Phewa Dam (right) and bypass channel

(left), Phewa Lake, Dam Side, Pokhara, Nepal (Photo

by Sato, March 24, 2012)

Photo 17: Children swimming near the outlet bypass channel of Phewa Lake, Dam Side, Pokhara, Nepal (Photo by Sato, March, 2012)

Photo 16: Women washing clothes near the outlet bypass channel of Phewa Lake, Dam Side, Pokhara, Nepal (Photo by Sato, March, 2012)

FULBRIGHT LETTER-6 Water: Phewa Lake

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Studying the Phewa Lake watershed is challenging: it requires backpacking, boating and paragliding.

The landing site is located by Phewa Lake. A failed landing can result in serious consequences. I observed a failed landing in front of my eyes. The man had a serious concussion but his helmet saved his life.

Photo A3: Me at the Sarankot take off site. “To fly, or no to fly, that is the question.” (Photo by R. Sato, 2/4/2012)

Photo A4: Paragliding landing site: Rachel (left) after her safe landing and someone after his

failed landing (right) (Photo by Sato, 2/4/2012)

Photo A1: Me, backpacking to study the Phewa Lake watershed (Photo by R. Sato, 1/21/2012).

Photo A2: Paragliding from Sarancot to study the Phewa Lake watershed (Photo by R. Sato, 2/4/2012).

FULBRIGHT LETTER-6 Water: Phewa Lake

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Among the backpacking, boating and paragliding I have done, the boating (with a boatman) was the easiest.

There are a number of restaurants along the lakeside: dishes of local fish are common in a menu.

References

1. http://en.wikipedia.org/wiki/Phewa_Lake 2. Aryal, V. Phewa Lake watershed area: A study on the Challenges to Human Encroachment. Proceedings of Taal 2007: The 12th World

Lake Conference: 2292-2299. 3. Pokharel, S. Conservation of Phewa Lake of Pokhara, Nepal (Publication Year unknown); http://rcse.edu.shiga-u.ac.jp/gov-

pro/plan/2008list/06-020503.pdf (accessed 3/25/2012) 4. JICA/SILT (2002). Conservation Development Study on the environmental conservation of Phewa Lake in Pokhara, Nepal. Final report

submitted ny SILT Consultants to JICA/Nepal, Kathmandu.

Photo A5: Leaving from the lakeside jetty to Barahi Temple on island (Photo by A. Lamichhane, January 14, 2012). From front: Rachel, Sirika, Anmol, Me, and boatman.

Menu advertised by a restaurant, Lakeside, Pokhara, Nepal (Photo by Sato, March 2012)

My dinner, Lakeside, Pokhara, Nepal (Photo by Sato, April 12, 2012)

Photo A6: Me, relaxing on a boat at the

Barahi Temple jetty on the Nepalese New

Year day (Photo by Sachitra, April 13,

2012).