River Taf Water Quality Report: August 2026

This report provides an analysis of the water quality data collected across the River Taf in August 2026 at Llandowror, the Water monitoring station, Whitland Church, Login, and Glogue, with comparisons to results from July 2026 where available.

Water temperatures across the main river remained elevated in August, consistent with summer seasonal norms. Downstream temperatures were recorded at 21.0°C at Llandowror, 20.4°C at the Water monitoring station, and 19.9°C at Whitland Church. Upstream locations experienced minor increases compared to July, with Login measuring 18.4°C (up from 16.9°C) and Glogue measuring 16.3°C (up from 14.8°C). Weather conditions during sampling were recorded as sunny at Llandowror and cloudy across the remaining sites.

pH measurements across all five monitoring locations remained within standard ecological guidelines of 6.0 to 9.0. Values along the lower stretch of the river were consistent, measuring 7.0 at Llandowror, 7.0 at the Water monitoring station, and 6.9 at Whitland Church. Upstream at Login, the pH was recorded at 7.7. At Glogue, which was introduced as a new monitoring station in July, the pH moved from a reading of 10.1 in July down to 8.0 in August, placing it comfortably within the normal range.

Dissolved oxygen levels remained stable and healthy throughout the river system, ranging between 7.5 mg/L and 8.3 mg/L along the lower stretches, and between 9.4 mg/L and 9.5 mg/L at the upstream locations.

Nutrient parameters showed minor variations across the catchment during August. Phosphate levels along the downstream locations were recorded at 0.60 mg/L at Llandowror, 0.50 mg/L at the Water monitoring station, and 0.26 mg/L at Whitland Church, while upstream sites measured 0.22 mg/L at Login and 0.13 mg/L at Glogue. The upstream sites fall within the limits of “good ecological status” whilst downstream at Whitland Church, the Water monitoring station, and Llandowror the phosphate levels are in the moderate to poor region. The root cause of this is not known.

Nitrate levels generally decreased from July along the main river, measuring 1.2 mg/L at Llandowror, 0.7 mg/L at the Water monitoring station, and 1.1 mg/L at Whitland Church. Glogue recorded a nitrate reading of 1.9 mg/L (down from 2.7 mg/L in July), while Login recorded 1.6 mg/L. All of these are in the elevated region but fall short of being excessive (>5 mg/L).

Ammonia readings remained low across all sites, ranging from 0.00 mg/L to 0.04 mg/L, all well within the target threshold of less than 0.3 mg/L. Water conditions were noted as cloudy across the main channel stations and clear at Login.