Portskewett The village lost its railway station (on the Newport to Gloucester line) when it was closed under the Beeching Axe in 1964. Black Rock, on the Severn estuary immediately south east of the village, has been an important crossing point of the River Severn for many centuries. Numerous coins found in the mud show that it was in constant use throughout the Roman period, on the route between Aquae Sulis (Bath) and Venta Silurum (Caerwent). By the 18th century, a regular ferry service crossed the Severn estuary from Black Rock to New Passage on the Bristol side, carrying passengers, cattle
Aphanizomenon flos-aquae samples exceeded the safety value of 1 µg microcystin per gram. University professor Daniel Dietrich warned parents not to let children consume "A. flos-aquae" products, since children are even more vulnerable to toxic effects, due to lower body weight, and the continuous intake might lead to accumulation of toxins. Dietrich also warned against quackery schemes selling these cyanobacteria as medicine against illnesses such as attention deficit hyperactivity disorder, causing people to omit their regular drugs. A Canadian study studying the effect of "A. flos-aquae" on the immune and endocrine systems, as well as on general blood physiology, found that eating