Upper lake is an east westerly elongated typical tropical lake, was built by king Bhoj of Dhar (1,000-1,055) by constructing a massive earthen structures across Kolans river. The lake has catchment area of 361 km² with a water submergence length of 12 km and maximum width of 1.75 km at Full Tank Level. Available records reveal that the lake area was approximately 2 km² in the beginning. In 1963 the water spread area of the lake increased form 13.8 km² to maximum of 36.1 km² by constructing 11 radial gates at Bhadbhada waste weir.

Catchment area of the lake falls into geographically separated two different administrative units (districts). 84 villages in the catchment support population of approximately 0.3 million. 80% of the catchment is rural which has agriculture as predominant land use covering roughly 251 km² of the catchment. The excess water from this lake overflows into another lake called Kaliasot through the waste weir constructed in the west end of the lake. This water finds its way into Yamuna river through Betwa river. Bhopal Municipal corporation is the principal custodian of this lake. On the lake embankment is a garden and the road laid on it that connects the old city with the new which shows fast urban development. Recently two new roads have been built, one across the lake and the other running along its east shoreline.

Deccan trap basalt and Vindhyan sand stones are the principal rock formation of Bhopal district. These traps have low porosity and permeability and therefore not favourable for ground water storage. Weathering of the basalt rocks has given rise to black cotton soil in the region.

The lake is primarily used for drinking water supply to the city. Other uses include tourism, navigation fisheries and entertainment. Most of these are in harmony with the sustenance of lake ecology. For large number of fishermen families it is a source of livelihood.

In the past, the major threats to this lake have been the untreated sewage waste water entering the lake from its urban catchment and the non point sources of waste water and solid waste emanating from human activities in its fringe area. Apart from this, what still exists, is the siltation of this lake due to the soil eroded from its predominantly agriculture catchment which is drained by surface runoff carrying soil and agrochemicals. The lake ecosystem was infested by macrophytic growth in its littoral area and floating weeds spreading over the lake. Water quality also deteriorated due to these threats. A major lake conservation and management project was undertaken by the state government with support from the then Overseas Economic Cooperation Fund (OECF) Japan. Successful implementation and still continuing efforts by the state has significantly improved its ecological status as reflected in its improved water quality, biological diversity, fish productivity and overall ecohydrology.

The lake is one of the 26 Ramsar sites in India. Was recognized as wetland of international importance under the Ramsar convention in 2002 due to its rich biodiversity value. Apart from several species of flora and fauna the lake is a habitat for 180 migratory and local avian species including white stork, black necked storks, bar headed gees, spoonbills, sarus cranes etc, which were rarely sighted in the past are now reappearing.
( Dr. Pradeep Shrivastava, Professor & Head, Environmental Science Limnology, Barkatullah University, Bhopal INDIA )