Sunday, 29 March 2015

Hilgay: water levels, birds and pumps

Nick Carter, Conservation Officer (Fens)

The South West corner large compartment flooded, photo Nick Carter
Well, we did it, just about. We reached the target level of 11.59 (1.59m above sea level) in the storage lagoon and maintained it for a month at Hilgay in the Wissey Valley Living Landscape. We have also been able to wet-up much of the rest of the site too so for the first time we have had significant areas of standing water in all four corners. Unfortunately the higher water levels have also exposed some of the issues on the site. The northern shores of the lagoon have suffered some minor wave erosion with the south westerly winds we have had over the winter. It also looks as though a seal has blown in the outlet sluice so that when it is closed water leaks into the surrounding land under the pressure of water from the lagoon. Both of these issues mean that we will have to let water out of the lagoon to plant reeds along the eroded banksides to give greater protection and to replace the leaking seal.  Letting water out means we should reach the target levels in all the other compartments of the site which will help kill off terrestrial weeds and help the spread of naturally occurring reeds and those that were planted in 2013.

Oystercatcher and brent goose, photo by Nick Carter
The higher water levels have also meant wildfowl numbers have built up over the winter. On the 25 March there was a record 50 tufted duck on the site, along with 3 great crested grebe. Coot, shoveler, shelduck, mallard, gadwall, teal, pintail and feral greylag, Canada and Egyptian geese are all present. A surprise visitor was a solitary brent goose which dropped onto the lagoon for a short time one misty morning. Several pairs of lapwing and one pair of oystercatcher seem to be settling down for the breeding season while snipe are still in small winter flocks. Unfortunately with the higher water levels in the lagoon it looks as though we will lose our little ringed plovers and avocets. No sand martins have turned up yet, although it is early days, but we have smoothed some of the sandy ditch sides to encourage breeding.

Panks Pump engineers winching pump out of chamber to service it,
photo by Nick Carter
It has been one year since the lagoon pump was installed by Panks Pumps so it was time for its annual service. This is not as easy as it sounds as the pump has to be winched out of a 4m deep chamber before work can start. Fortunately all seems well. It has been running for over 250 hours during the year which does not sound too much but for the first few months there was very little water on site for it to pump. It will be much busier over the next 12 months.

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