Nestled within Cardiff, Wales, Llanishen Reservoir provides a welcoming lakeside setting. Having been designated as an official bathing water site in 2025, the location undergoes routine water quality assessments, currently rated Excellent. In addition, dogs are permitted during winter months.
Sediment type has not yet been recorded for this site. Underfoot conditions and bank composition may vary.
Water quality is classified as excellent, meeting the highest cleanliness standards. Bacterial counts (E. coli & Intestinal Enterococci) are consistently low, posing negligible health risks.
Bacterial levels are highly susceptible to storm runoff. Heavy rainfall in the local catchment is likely to trigger storm overflows and agricultural runoff, rendering the water temporarily unsafe.
Tested weekly by the Environment Agency England for bacteria levels (E. coli & Intestinal Enterococci) between May and September.
Monitored as an inland lake bathing water. Inland lakes and reservoirs have low water circulation compared to tidal waters, meaning bacterial levels can persist longer after rainfall.
Unknown is the regional utility responsible for waste water treatment, sewage infrastructure, and storm overflow management in this catchment area.
Officially designated as a protected bathing water site in 2025. This designation mandates regular public health monitoring.
Governed under local district sanitation and environmental safety regulations in the Cardiff area.
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