The pond was dug by hand around 1810 as a header reserve for  Hempstead_Mill.  The mill was suffering from insufficient water despite 4 other smaller ponds having been made between the mill and Selbrigg Pond.
The Tithe map of 1840 shows a pond around 9 acres in size with streams from Bodham and Baconsthorpe entering the pond. Indeed the pond stretched back to 'Selbrigg Road' In Lower Bodham.
The parish boundary between Hempstead and Bodham runs through the pond, presumably along the original line of the streams.
Subsequently to the original pond being dug, a duck decoy was incorporated - a funnel shaped area that was netted as a way of catching ducks. Furthermore, a boat house was subsequently built mid-way along the Northern bank, little now remains.
By the 1950's the original pond had silted up quite badly.
Traction engines were used to dredge the pond. However this was not completed owing to the retaining bank wall (with the sluice in) moving with the disturbance.  To try and stabilise the bank trees were planted along it. The Sluice was replaced at the same time and the water level maintained about 5" higher than at present.
By 1970 the pond was becoming polluted and fish dying so the two streams that fed it - from Baconsthorpe and Bodham, were diverted around the south side of the pond. Since that time it has been entirely spring fed and is recorded as having some of the purest pond water in the country.
Selbrigg official website

Francis Feilden announced his intention to rejuvenate Selbrigg Pond which was last dredged by his father in the 1950's. The trees will be coppiced (last done about 40 years ago); the pond dredged to remove the overgrown rushes. There will be some delay for the 6 days it will take to finish the work beside the road.
Church & Village News - March 2011

At the beginning of 20th century, when the turbine was fitted, there were 5 sources of water - mill dam, upper pond (swept away in the 1912 floods) Horsepit Pond, Old Decoy (Selbrigg Pond) and New Decoy.
enough water to work a few hours a day, the Hempstead_Mill worked a regular twelve hour shift, its water supply being topped up at the main mill pond by releases from Selbrigg Pond, the upper mill pond (until it was swept away in 1912), from Horsepit Pond and occasionally from the Small Decoy. This arrangement meant that the miller had to walk or ride to operate the sluices of these other ponds at regular intervals. The roadway past Hawksmere, turning up hill to Horsepit Pond and the Red_House, leading on to Selbrigg, would have been built for this purpose.
Hempstead, A Norfolk Village - Robin Carver, 2000

Slightly further up the river Glaven was Selbrigg pond, which was dug out two hundred years ago to provide additional head waters for Hempstead_mill. When I mentioned this to my father at home it was assumed I was talking of Felbrigg , as no one had ever heard of Selbrigg. There is no village of Selbrigg, just a road of that name going to Bodham, the next village, so it not surprising that nobody has heard of it.
In the spring of 1963 Selbrigg pond was frozen over like the rest of the countryside. This was during the Big Freeze. A Big Freeze it may have been by our standards, but the pond was not frozen so solid that you could walk all over it. Being foolish young children we enjoyed playing on the expanse of ice. How deep was it? I don't know but deep enough to be very dangerous. We could easily both have drowned. I was on the ice with another boy called Ward when it began to crack. I remained on the cracking ice but Ward fell into the freezing water. Luckily I was able to pull him out. He must have been very cold as we cycled back to school. Despite the cold weather we were wearing school uniform - shorts of course! All boys did in those days, even 14 year olds, and his were soaking wet as well.
Joseph Mason

Francis Fielden announced his intention to rejuvenate Selbrigg Pond which was last dredged by his father in the 1950's. The trees will be coppiced (last done about 40 years ago); the pond dredged to remove the overgrown rushes. There will be some delay for the 6 days it will take to finish the work beside the road.
Village News - March 2012

I went to Selbrigg at about 16.45 to look for wildlife to photograph.
There was just myself and a young lad fishing.

The swans were centre left in the pond.
I suddenly heard quite a loud sound, a cross between strong wind and water flowing fast.
I’ve never heard it before and it was almost alarming.
I looked over and centre right was a raised section of water with a spiral above it.
It then started moving to the left towards the swans.
It almost looked as if a large fish was swimming towards them just under the surface but it wasn’t that.

As it moved towards the swans it speeded up and spray was visible above it.
When it got closer to the swans, they panicked and swam away fairly fast.
The ‘lump’ of water carried on and eventually disappeared into the reeds, having gone right across the centre of the pond.
The young lad and I had both watched it and we were both quite sobered by the experience.
Jonathan Neville - 30th July 2020

The spring-fed Selbrigg Pond was originally dug in 1810 as a water reserve for Hempstead_Mill. In the 1960s, however, the Mill stopped operating and the pond become an important home to a wide range of aquatic wildlife not found in the main River Glaven. As a result, Selbrigg is now designated as a ‘County Wildlife Site’.
The brick retaining wall - built to keep the water at a level of 1m higher than the highway - was beginning to crumble as trees were growing too close to the edge. There was a risk of failure and a breach in the wall, which could have led to water running across the road and descending downstream, carrying debris with it.
Norfolk Rivers Trust (NRT) re-built and strengthened the pond wall. Galvanised trench sheet pilling was placed 250mm in front of the existing brick wall and finished with a hardwood capping and waling. The gap between the wall and sheet was filled with concrete for extra strengthening. A new purpose made stop log weir was incorporated into the sheet metal piling, and repairs were made to the existing brick culvert. A new sluice system was installed into the new wall, with piping extending under the road.
At the same time as these works were being carried out, a large amount of accumulated silt was removed, and the encroaching reed growth was pinned back. A contractor, who had designed and modified equipment to create a giant claw that was fixed to the head of a digger, was used to ‘comb’ out the reed before suction dredging was used to remove the silt.
NRT is pleased to report that the pond is now one of the largest sources of clean water to the River Glaven.
Norfolk Rivers Trust