Tens of thousands of fish have been killed in rivers in the Midlands by a combination of pollution, high temperatures and thunderstorms.
The Government's National Rivers Authority said last night that it had ''written off'' fish life in the river Tame because of the oxygen starvation that resulted from this combination, and was struggling to save the larger river Trent.
Four-and-a-half tonnes of liquid oxygen were being pumped into the river near Burton-on-Trent in Staffordshire. Further downstream, three large bankside coal-fired power stations which had been shut down for the summer began pumping river water through their giant cooling towers in an attempt to aerate it.
The high temperatures of recent weeks cut the concentrations of oxygen dissolved in the rivers. Then the low pressure air associated with thunderstorms further reduced levels of the life-giving gas.
The final blow was the heavy rainfall, which caused a large flow of polluted, deoxygenated water from storm drains into the rivers. Tony Stanley, area general manager for the NRA's Severn Trent region, said oil, diesel, petrol and rubber had been building up on the region's roads, yards and car parks during the long dry spell.
''All the rain washed that and other dirt into the river Tame, plus some sewage from storm sewer overflows. Along with the high temperatures and low air pressure, it was a recipe for killing fishes,'' Mr Stanley said.
The river drains most of Birmingham and its surroundings, and in summer nearly all of its flow consists of effluent from sewage works.
None the less, healthy fish populations had built up in the lower, rural reaches just before the Tame joins the Trent at Lichfield in Staffordshire.
The NRA tried to save them by bringing in aerators which pump air into the water, but the attempt failed because oxygen levels were too low.
The authority then brought in one of only two large oxygen dispensers in the country to save the Trent. ''So far we think only some 500 fish have died, and we think we can succeed,'' Mr Stanley said. Fish have also died in the Erewash, the Soar and some other rivers.Reuse content