River Corran and Mackerel Lake Stream water testing results-August 2026

1. Mackerel Lake Stream Catchment

This catchment covers Llandawke, Broadway Caravan Park and the Culvert bypass. Due to the dry summer conditions Llandawke had no water and remained unsampled in August.

Ammonia (Excellent): Both sampled sites maintained excellent background levels. Broadway Caravan Park registered 0.02 mg/L (down from 0.03 mg/L in July), while the Culvert dropped to 0.00 mg/L (down from 0.09 mg/L in July), remaining well below 0.3 mg/L which itself is considered ecologically good.

Nitrate (Elevated): Broadway Caravan Park dipped slightly to 1.3 mg/L (from 1.5 mg/L in July). The Culvert increased to 2.1 mg/L (up from 1.3 mg/L in July). Both fall into the elevated tier (1.0 – 4.9 mg/L) though still well below “excessive” levels.

Phosphate (High / Upper Medium): Broadway Caravan Park rose to 0.30 mg/L (up from 0.23 mg/L in July), placing it right at the boundary where high levels can trigger algal blooms. The Culvert improved to 0.19 mg/L (down from 0.28 mg/L in July). It is important to note that the sample at Broadway Caravan Park was from a pool with very little flow and may not be representative of the water course as a whole as can be seen with the results from the Culvert.

pH & Temperature: The Culvert maintained a stable pH of 8.1 (identical to July) with a water temperature of 17.7°C.

2. Main River Corran Catchment

This section evaluates the primary river sampling points: Abercorran, Glancorran, Horsepool Tributary, Hill Farm Stables, Horsepool Road Bridge, and Newbridge Road Bridge.

Nitrate Trends

Glancorran: Rose to 5.3 mg/L (up from 4.1 mg/L in July), crossing into the excessive category (>5.0 mg/L).

Abercorran: Improved from its excessive July reading of 6.0 mg/L down to 3.9 mg/L.

Other River Sites: Horsepool Tributary (4.1 mg/L), Hill Farm Stables (2.8 mg/L), Horsepool Rd Bridge (3.7 mg/L) and Newbridge Rd Bridge (2.0 mg/L) all stayed within elevated boundaries (1.0 – 4.9 mg/L).

pH Balance (Optimal to Slightly Alkaline)

All samples remained within the safe ecological envelope (6.0 – 9.0):

Abercorran: 8.5 (up from 7.1 in July)

Glancorran: 7.6 (up from 7.2 in July)

Horsepool Tributary: 7.5 (up from 6.7 in July)

Hill Farm Stables: 7.4 (up from 7.3 in July)

Horsepool Rd Bridge: 7.1 (up from 6.6 in July)

Newbridge Rd Bridge: 6.2 (down from 8.3 in July, remaining safe but closer to the acidic threshold)

Phosphate & Salinity

Phosphate: Most river sites remained within the good ecological status range (0.077 – 0.306 ppm): Horsepool Rd Bridge (0.23 mg/L), Newbridge Rd Bridge (0.22 mg/L), Glancorran (0.19 mg/L), Horsepool Tributary (0.11 mg/L), Abercorran (0.09 mg/L), and Hill Farm Stables (0.06 mg/L).

Salinity: Abercorran experienced a notable increase to 0.80 (up from 0.19 in July), potentially reflecting high mineral concentration during lower than usual river flow.

Water Temperature & Dissolved Oxygen

Temperature: Water temperatures ranged between 16.6°C (Abercorran, Horsepool Tributary, Hill Farm) and 18.2°C (Glancorran).

Dissolved Oxygen: Oxygenation was exceptional across the catchment, spanning 9.3 mg/L (Glancorran) to 11.0 mg/L (Newbridge Rd Bridge). All values exceed the 8.0 mg/L target for very healthy waters.