River Corran and Mackerel Lake Stream Water Test results -July 2026

WATER QUALITY REPORT: JULY 2026

1. Mackerel Lake Stream Catchment

This catchment monitoring includes Broadway Caravan Park and the Culvert bypass. Due to dry summer conditions, the Llandawke site had no water and could not be sampled this month.

• Ammonia: The stream shows very positive results, with Broadway Caravan Park registering at 0.03 mg/L and the Culvert at 0.09 mg/L. Both sites sit comfortably within the ecologically good threshold of less than 0.3 mg/L.

• Nitrate: Nitrates are currently classified as elevated across the catchment, with Broadway at 1.5 mg/L and the Culvert at 1.3 mg/L. While these figures reflect seasonal summer baselines, they safely avoid the excessive threshold of 5.0 mg/L or higher.

• Phosphate: Phosphate levels sit at the higher end of the medium safety range (0.06 to 0.3 ppm), with Broadway at 0.23 mg/L and the Culvert at 0.28 mg/L. These areas should be closely watched, as pushing past 0.3 ppm can lead to localised algal blooms and drop oxygen levels.

2. Main River Corran Catchment

This catchment covers the main channel monitoring stations: Abercorran, GlanCorran, Horsepool Tributary, Hill Farm Stables, Horsepool Road Bridge, and Newbridge Road Bridge.

• pH Balance: The entire river system exhibits excellent, stable water chemistry. All monitored sites sit firmly within the optimal acceptable range of 6.0 to 9.0 needed to protect aquatic life. Most of the river remains close to neutral—ranging from 6.6 at Horsepool Road Bridge to 7.3 at Hill Farm Stables—while Newbridge Road Bridge maintains a slightly more alkaline profile at 8.3.

• Nitrate Enrichment: High nitrate levels represent the primary area of concern for the river this month. Abercorran has jumped into the "excessive" category at 6.0 mg/L. The remaining sites all display elevated seasonal trends, with Hill Farm Stables at 4.3 mg/L, GlanCorran at 4.1 mg/L, Horsepool Road Bridge at 3.9 mg/L, and Newbridge Road Bridge at 3.0 mg/L.

• Ammonia: Background ammonia levels remain exemplary and virtually non-existent across the river. GlanCorran registered a trace amount of 0.01 mg/L, while all other stations recorded a pristine 0.00 mg/L.

• Phosphate: Every station along the main river is securely positioned within the safe medium tier (0.06 to 0.3 ppm). Levels range from a low of 0.08 mg/L at Hill Farm Stables up to 0.24 mg/L at GlanCorran.

• Conductivity and Salinity: Electrical conductivity ranges from 180 µS/cm at Hill Farm Stables to 218 µS/cm at Abercorran. These numbers are well within the standard 100–250 µS/cm bracket of a healthy river, proving there are no active sewage spikes or intense agricultural run-off events. Baseline salinity tracks predictably low between 0.08 and 0.19.

• Temperature and Dissolved Oxygen: Normal summer warming is evident, with the main channel holding between 15.4°C and 16.7°C, while Newbridge Road Bridge hit 18.8°C and the shallow Culvert bypass reached 19.6°C. Crucially, despite the warmer water, Dissolved Oxygen remains exceptionally healthy, running from 8.9 mg/L to 10.7 mg/L. This is well above the critical 5.0 mg/L threshold and indicates a highly resilient, well-oxygenated ecosystem.