Roy Pickford and Bob Davies used to spread a "friendly" bacteria in the slough to control the mosquito larvae.
The original flap on the culvert was made by Bob Davies, consisting of a piece of plywood wedged in place by a big rock. Ken Bolster improved on this by making a hinged metal flap which allowed the water to flow out of the slough but restricted the salt water flowing back in on high summer tides.
He replaced it at least twice but it's rusted out again. According to Ken the mosquitoes (larvae? eggs?) can live in the mud 7 or so years.
Comes a high tide over the mud and hey presto - salt marsh mosquitoes in abundance!
Pat English