FISHING has been suspended on the Wye and Usk due to the heatwave, while extra water is being released upstream to try and cool it.
Both rivers are drying out because of the record temperatures, causing fish to die, say the Wye and Usk Foundation, which agreed with Natural Resources Wales and Welsh Water on Friday to release water from the Elan Valley reservoirs to increase the Wye flow in a bid to reduce its temperature.
Ross-on-Wye Angling Club has banned all fishing on its five-mile stretch during the heatwave, following the foundation’s suspension of salmon and trout fishing earlier last week.
A club post said: “Due to high water temperatures and very low water in the River Wye the Committee of ROWAC have decided to close all waters for the duration of the hot weather that is forecast over the next week.
“Water Temperatures were recorded at 18C during the week and with a heatwave with air temperatures expected to be in the low 30s over the weekend and which will peak at possibly 32C.
“This closure applies to both ROWAC members and visiting day ticket anglers. There are no exceptions and club bailiffs will be patrolling the banks to ensure no one is fishing.
Rainfall between March and June was down by more than a third, and Usk and Wye Foundation chief executive Simon Evans said: “As far as fishing is concerned, it’s the warmth of the water that is our biggest headache. We’ve already got some fish dying in certain places.
“The problem is you can’t keep battering the ecosystem in the way that we are – we’re oscillating between monster flood to severe drought, to severe hot to monster flood again.
“And each one of these events just stresses everything in a new way.”
The water levels are at “basement levels” in some stretches.
And the foundation posted after its discussions with the NRW and WW last week: “The forecast is looking very hot and sunny from Sunday to Tuesday, but the Wye is currently extremely low.
“This means that the lives of salmon, which are holed up in the lower reaches, are at risk due to water temperatures becoming fatally high.
“We can’t change the weather, but we can increase the flow and therefore reduce the risk of ponded pools ‘cooking up.’
“Yesterday, the Wye and Usk Foundation came to an agreement with Natural Resources Wales and Welsh Water to use the water within the Elan Valley reservoirs to increase the flow in the river.
“This water needed to be released today for it to be the most effective. Due to the length of the river, this water would require a few days for it to reach the bottom by Tuesday when we expect the situation to be at its most serious.
“Today’s cooler conditions would also reduce the risk of this release increasing the water temperatures as it flows over scorching rocks.
“Studies have shown that the cooling effect of a release of this scale will not extend much past Builth, but it will push cooler water from the upper river, downstream. This will help push the hot water at the bottom out.”
The group called for the release of 1,000 million litres per day, but had to settle for 640 million litres per day until 12 noon on Monday.
“It is especially important that it gets through to the tide and we have been liaising with abstractors to try to ensure this,” he added.
“We are eternally grateful to the Herefordshire farmers who, having had the situation explained, have agreed to reduce and where possible pause entirely their abstractions for crop irrigation at this critical time.
“Our thanks to Welsh Water, the farmers, Natural Resources Wales and the Environment Agency for their cooperation in this effort.”