Erroneous environmental and economic development measures in Halda valley have put the river and its rich biodiversity at stake.
The measures include faulty site selection to protect river banks, rubber dams to increase crop production and industrial effluent discharge.
The river Halda is considered the only gene-bank of pure Indian carp fish — Ruhi, Katla, Mrigel and Kalibaush — globally, and hosts around 200 Gangetic dolphins categorised as endangered by International Union for Conservation of Nature (IUCN).
But recent years have seen a gradual decrease in the fish egg production.
In 2016, Chittagong University’s (CU) zoology department found 60 fish species in Halda river. There were 86 in 2009.
Additionally, the amount of carp fish-eggs has decreased drastically in last four decades.
In 1970, about 40-50 kgs of fish-eggs could be collected annually, which came down to 12 kgs in 2015 and in 2016 no egg was harvested at all.
However, egg harvest has been increasing over the last two years, professor Manzoorul Kibria, who had led the CU study told Bengal Delta.
This outcome, the professor explained, is due to strict measures to stop indiscriminate fishing with guards deployed along a 20-kilometre stretch (Sartarkhal to Kalurgaht) of the river — which is considered the breeding ground.
It is also the source of about 180 million litres of fresh water for about 7 million inhabitants of Chittagong city.
Destructive bank protection
In 2018, Bangladesh Water Development Board initiated a 22km river bank protection project on Halda which destroyed the fish breeding grounds.
Usually, hilly rivers run the deepest at their turns and that is where the fish love to breed. There are nine such turns, which are also vulnerable to erosion.
The project dumped sandbags at those places to reduce the depth and later built embankments with concrete blocks.
Consequently, the river lost at least six major breeding grounds of carps, said Manzoorul Kibria at who has been working on Halda for long.
A high-level government committee has already asked the water development board to restore the breeding grounds as soon as possible.
Ruinous rubber dams
The government built a rubber dam at Fatikchhori in 2012 to irrigate 1,000 hectares to raise agricultural production in the area.
Consequently, the 15-20km stretch downstream from the dam has dried up raising salinity during lean seasons.
The zoology professor said there was not enough clean water downstream from December to March for the fish to survive. The plankton and phytoplankton that the river carries from upstream hardly reaches beyond the dam during the dry months.
The environment department survey of 2018 found the reason behind dwindling aquatic species to industrial discharge.
The survey report stated that river pollution could be reduced with ECA rule.
Currently, about 20/25 industrial outlets including tanneries, dyeing houses, paper mills and power generation centres operate along the banks of Halda, draining their waste in it.
Declare as critical
Meanwhile the government has initiated a process to declare the river as an ECA to prevent pollution and unplanned infrastructural development on the banks of Halda.
“We are trying to declare the Halda as ECA as early as possible, but are facing difficulties to finalise the stretch of the river that will remain protected,” said Fahmida Khanam, a director of the environment department.
It has been planned to declare 107km strip of Halda, from its origin at Ramgar of Khagrachhori to the confluence of Karnaphuli in Chittagong as ecologically protected area.
Images by GM Mostafizul Alam
In 1999, the government formulated Ecological Critical Area Act, to protect some of the special ecological areas under threat. Currently there are 13 such areas.
Ecologically critical area means the area, which is unique in biodiversity but is in a sorry state due to man made problems and needs protection from further degradation.
The environment department issued a draft gazette on March 31, 2018 for comments from related stakeholders.
Fahmida Khanam told Bengal Delta that, “It will take at least a year to declare the river ECA because of the difficulty to establish the stretch of the river that will be considered protected.”
The environment department, said Fahmida Khanam, will send an application to the ministry once the Center for Environmental and Geographical Information Services (CEGIS) digitises stretches of Halda’s banks on the both sides.
GM Mostafizul Alam is a Dhaka based journalist works at Channel24 as a Senior Reporter . He can be reached @email@example.com