‘THOUSANDS’ of fish that were discovered on the banks of the lake at Marston Park in Frome on 26th August, died because of a drop in oxygen levels in the water.
The recent long spell of hot weather and heatwave, combined with a lack of rain meant that not enough water was flowing into the pond, which reduced the amount of oxygenated water available to the flora and fauna.
Marston Park provided an update a few days after the incident on social media saying, “After thorough inspection of the site, the Environment Agency (EA) has listed the following contributing factors to the incident: lack of rain for months has led to Marston Brook not producing any flow into Marston Pond, so there isn’t any fresh oxygenated water. Water levels in the lake have dropped by 2ft-3ft and at night, the oxygen produced in the day through photosynthesis is used up by the plant life.
“Rainfall on the night of the incident caused low pressure, which also prevents and inhibits oxygen in the water. Water should have 40%-50% oxygen. The morning after the event saw some parts of the lake were at 5% oxygen – fish die at 12%-15%.
“Oxygen levels fluctuated dramatically within a short space of time, so rapidly that even fishermen who were fishing the night of the incident were unaware of it happening until the morning.
“Huge algae blooms have appeared on the lake; when it dies, micro-organisms feed off it, which uses up the oxygen in the lake. Water tests were done on the lake and the incident was not due to nitrates, nitrites or ammonia. We did not kill thousands of our own fish as a PR stunt.”
Marston Park say that the EA has agreed that dredging the lake and reinstating the depth would dramatically increase the amount of oxygen, however this would require planning permission which the cost of which could rise considerably.
The quote from Marston continues, “We have quotes for our restoration plans, and it will cost hundreds of thousands of pounds to dredge only a small corner of the lake – approximately five acres – so for the full 25 acres it could cost many times this amount.”
An Environment Agency spokesperson said, “Every year, we respond to hundreds of reports of fish in distress because of dry and warm conditions. In certain circumstances, we also support fisheries. However, fish in privately-owned ponds are the responsibility of the owner.
“We received reports via our incident hotline of fish in distress at Marston Pond, a private fishery. We gave advice and, as soon as resources allowed, our fisheries officers attended where they discovered a large number of dead and distressed fish within a 20-acre lake. An algal bloom caused dissolved oxygen levels to drop rapidly and we are supplying equipment to the fishery to assist with aeration, as well as monitoring the situation.”
If you see dead or distressed fish in rivers, contact the EA 24/7 hotline 0800 807060.
