BEIRA LAKE SCHEME 100 years old: Upkeep Vital.

  Beira Lake has been a landlocked water body built over five centuries back by the Portuguese, inter alia, for defence purposes. Later reports like Ceylon Sessional Papers of 1907 states that ordinary water level was about 9 feet above Mean Sea Level (MSL) spread over 400 Acres and its `sanitary condition not good’. History of the lake briefly given as,

        1879- A pure lake in which many plants could thrive,

        1891- A polluted lake, only one sewage feeding water plant hydrilla could hold on,

        1901- A cesspool, plant life degenerated to the species algae which alone could live under      condition of sewage contamination.

The geographical and physical layout of the Beira Lake Scheme as seen today is the result of a proposal to improve the condition of lake and approved in Ceylon Sessional Papers 1920, and referred to as the Colombo Lake Development Scheme. 

The topic of improving the quality of water in the Beira Lake using new technology has come up now which prompted to look at this subject by the writer, who as a young engineer handled, inter alia, lake system maintenance 50 years ago for several years.

A newspaper report dated 9^th October 1993 (30 years ago) says “The Beira is one of the most polluted water bodies in Sri Lanka, situated in the heart of Colombo city,….stagnant, of an unusual green colour emitting a very disagreeable stench.” Before that time, in 1991, a World Bank funded project called Metropolitan Environment Improvement Project with Beira Lake restoration as one of its tasks was ongoing, under the Urban Development Authority.

Ten years after above report, next news item dated 10^th October 2003 carries the title “A Pure Beira Lake at last?”, but said “There has been serious bungling”, after spending 70 million Rupees to build new pump house and control structure at Nagalagam Street to pump Kelani river water into Beira Lake via St Sebastian canal to flush the Lake. Colombo city flood havoc of June 1992 had resulted in cut down of steel gate structure, report further states.   

Beira Lake Scheme constructed in the 1920s was based with the concept of lowering lake water level to 6 feet above sea level from about 8 feet. Total scheme consists of, East Lake (running nearly parallel to D.R.Wijewardena Mawatha), South West Lake (where Gangaramaya temple seema malakaya located), Galle Face Lake (near Presidential Secretariat) flowing to sea at the spillway, West Lake (behind Gall Face Green) connecting up to South West Lake, and all Lakes inter connected by canals and more importantly a 400 meters long canal connecting the Lake with Colombo Harbour. The water level of Beira Lake is held by three structures namely St Sebastian locks (near Maradana Technical College), McCallum locks (near Lake House on the opposite side) and Galle Face spillway (arc shaped weir with crest level at six feet above sea level).

East Lake holding biggest water area is connected to the Colombo Harbour through the harbour canal. Shippers having lakeside godowns and stores abutting the lake were afforded direct cargo handling facilities using lighters or cargo barges belonging to the Ports Authority. Also Ports Authority repair workshop for steel lighters of 100 ton cargo capacity was located there. As such this Lake was very active. East Lake is also connected to two basins having railway lines alongside and canal connection being located beneath D.R.Wijewardena Mawatha. Export goods like tea, rubber, coconut products in large quantities on railway carriages, brought alongside these basins, were directly loaded to cargo lighters and towed to harbour and loaded onto ships, saving much costs. One of these two basins no longer used for cargo handling is now the Pettah Floating Market, and visitors can see its size.

Thinking of the situation 50 years back, there were hundreds of squatter families living along the banks of the lake dumping all waste there. Many outfalls into the lake brought apart from storm water, unauthorized sewage, industrial waste and other pollutants. All rain water that falls on about 2000 acre catchment flows into Beira Lake carrying with it, garbage, dirt, all kinds of waste.  Pollution by Suduwella ditch coming from the General Hospital side falling near Gangaramaya end has been mentioned even in 1907 reports.

At that time the lake surface was covered with water hyacinth which is a freshwater weed, considered as an aquatic ornamental plant with colourful flowers. But as it covers whole water surface, clogging waterways and blocking the air-water interface thereby eliminating underwater fish life, was considered a nuisance. Water hyacinth also considered a menace as providing mosquito breeding ground.

 Unbearable stench emanating from green water with algae bloom did not exist, as remembered, in the presence of water hyacinth, as much of Nitrogen in the water being extracted by long roots. This depletes Nitrogen needed for survival and reproduction of algae. Water hyacinth grows in sewage, polluted water and absorbing contaminants thereby comparatively cleaning polluted water. Green algal blooms or thick layers of algae are said to form when water is warm and full of nutrients.

Water hyacinth, being a floating plant with hanging root system, is said to absorb heavy metals and plant nutrients like Nitrogen, Phosphorus. As such water hyacinth helps to retard green algae growth. It was thought with this knowledge to grow water hyacinth in confined areas in the lake with careful control. Using bamboos, 20 feet square confined areas were formed floating and anchored to lakebed with heavy weights, at predetermined points. Hyacinth plants placed in them to grow while rest of lake area cleaned manually using boats and men. It is recalled that unbearable pungent stench was not prevalent at that time. Small group of men provided with boats was moving around regularly to make sure that water hyacinth or any other undesirable objects were not polluting water area and even the banks which were lined with concrete slabs.

At some stage, a cleaning process was executed to suck & pump out lake bed sludge containing much pollutants, using a suction dredger with floating steel pipelines aligned to Galle Face sea and going into some distance in the sea in order to minimize beach pollution. Sometime later, attempts by other authorities were also seen with aeration attempts in lake waters, but outcomes unknown.

Those days even in 1980s, East Lake was busy with extensive movement of cargo lighters between the harbour and East Lake warehouses. McCallum Locks operation was thereby frequent. Loss of lake water through these Locks into sea during every lock operation as well as loss of water due to evaporation from lake surface necessitated compensation by pumping of water from St. Sebastian Canal into the Lake utilizing pumps at St. Sebastian pump house located near Maradana Technical College. Those days this canal had adequate water for navigation of small boats and also to pump into the Lake. It was also possible to assist in lowering flood waters in St Sebastian canal surrounding areas, during heavy flooding, by pumping water into lake. Any excess water in the lake will spill into sea at Galle Face spillway.

Beira Lake Scheme constructed about 100 years back, yet survive as explained above, with various improvements in water and land areas but with basic layouts yet remaining the same. It is the duty and responsibility of authorities to improve the lake waters and surroundings to make it a pleasing sight for everyone that visit the city.

Eng. D.Godage.