Too Warm? Go Cool! Wales’ Cold Water Dam Fed Rivers

Wales’ dam-fed rivers can offer great trout and grayling fishing, even during the driest weather.

Long spells of hot, dry weather can make many Welsh rivers off limits from a fish welfare perspective, as well as river flows being almost non-existent in times of drought.

Fortunately, Wales is home to several exceptional rivers that receive regular releases of cold water from reservoirs.

These compensation flows help keep water temperatures significantly cooler and with more flow than on many neighbouring rivers, creating ideal fly fishing conditions for trout and grayling throughout much of the summer.

If you’re looking to escape the heat, then these Welsh rivers are well worth considering.

Upper River Severn

Flowing through the beautiful uplands of Mid Wales, the upper River Severn benefits from cold compensation releases from Llyn Clywedog Reservoir. These releases help maintain both river flows and cooler water temperatures during dry spells, making this one of Wales’ most dependable summer trout and grayling rivers.

The river supports excellent wild brown trout fishing alongside a renowned grayling population, with fish over 50cm caught every season. Brown trout are also stocked in certain sections. The river is easy to wade for the most part, with a gravel bottom.

Visitors have several options. Llanidloes Angling Association offers affordable day tickets for its waters around the town, while Caersws Angling Association controls several miles of classic upper Severn fishing, with both day tickets and season permits available.

River Elan

The River Elan is one of Mid Wales’ hidden gems. Rising in the spectacular Elan Valley, it is directly influenced by the famous chain of reservoirs that supply Birmingham with drinking water.

The regular dam releases mean the river often remains cool and fishable when many other streams are struggling.

Although not a large river, the Elan offers delightful wild brown trout fishing together with a stock of grayling in truly beautiful surroundings. The wading can be a challenge, so a wading staff is recommended.

Most of the Elan fishing is controlled by Rhayader & Elan Valley Angling Association, with convenient day tickets available locally in Rhayader at Hafod Hardware and Daisy Powell.

Upper River Wye

The upper River Wye just south of Rhayader also benefits from the cooling influence of the Elan Valley reservoir system, from the junction of the river Elan downstream for several miles.

Fishing Passport beats such as Craig Llyn and Dolgau are helped immensely by this cold water; the result is some of Wales’s finest wild trout and grayling fishing, where cold, well-oxygenated water provides excellent sport throughout much of the summer.

Wild brown trout are plentiful on the upper Wye, while abundant grayling also provide outstanding fishing.

The upper Wye scenery is every bit as impressive as the fishing, with the river winding through rolling hills and peaceful countryside.

Day Ticket options are available on The Fishing Passport.

River Tryweryn and Upper Dee

North Wales also boasts an excellent warm-weather option. Water released from Llyn Celyn feeds the River Tryweryn before joining the upper River Dee near Bala, helping maintain cool temperatures even during prolonged dry periods.

The upper Dee has long been regarded as one of Wales’ premier grayling rivers and the wild brown trout stocks are improving each year.

The Tryweryn itself is an underfished gem, it is fast and rocky but near the junction with the Dee specimen trout and big grayling have been caught.

Bala & District Angling Association offer day tickets, which are widely available through local outlets.

River Rheidol

The River Rheidol near Aberystwyth in West Wales also benefits from regulated flows associated with the hydroelectric scheme upstream, with three large reservoirs located on the river system.

These releases help keep the river cool and provide fresh water during dry weather, although anglers should always be aware that water levels can rise quickly when generation takes place.

Even when not generating water baseline dam releases maintain temperatures, ensuring the Rheidol is always cool in the summer, well below any stress thresholds for salmonids.

While best known as a salmon and sea trout river, wild brown trout are present and in ever greater numbers, with fish over 2lb occasionally reported. The brown trout fishing is quite untapped.

Fishing is managed by Aberystwyth Angling Association, with day tickets available online through the Fishing Passport, from local tackle shops and directly through the club.

Fish responsibly this summer

Even on dam-fed rivers, water temperatures should never be taken for granted. Conditions can change from day to day depending on weather, reservoir management and river flows.

Carrying a simple stream thermometer is one of the best investments any trout or grayling angler can make.

If water temperatures are above 18 degrees, take extra care.

In water temperatures over 20 degrees, salmon, trout and grayling become stressed, and responsible anglers should always put fish welfare first by monitoring conditions and avoiding fishing when water temperatures become too high.