Keldmarsh is derived from the Scandinavian word for spring Kelda. This aptly describes the nature reserve, which in wet years sees several springs emerging, forming pools and streams of clear water. This water is fed by underground streams that run through the chalk bedrock. Where the chalk meets a layer of impermeable clay, water is forced upwards and emerges at the ground surface. Sadly in some years these springs can run dry, probably due to changes in surrounding land use and water extraction over the last few decades.
 
The site is covered by woodland which, due to changing ground conditions, appears to be making a transition itself. Crack willow and alder, trees fond of getting their roots wet, are giving way to young ash which survive better in the drier conditions. Some venerable ancient willows lie fallen, but their twisted trunks and stems still provide homes for wildlife in their nooks and crannies. Elderberry, hawthorn and blackthorn provide scrubby areas of cover and birds breeding on site include chiffchaff, blackcap and dunnock. Occasionally water vole will inhabit the site when water levels are high.

Some of the rarest species found at Keldmarsh are slime moulds. These strange ‘growths’ look like lichen or fungi, but are actually colonies of very tiny, primitive creatures, that act as one organism. Often found on wet, dead timber they can be seen to move if observed over several days. Wetland plants such as fool’s water-cress, yellow flag iris and marsh marigold are found in and around the wet pools and common frogs are a regular sight.

• Spring: Plants - Dog's mercury; Herb-Robert; Amphibians - Common frog
• Summer: Plants - Yellow flag iris; Marsh marigold; : Invertebrates - Red admiral; Small white; Orange-tip
• Autumn: Birds - Song thrush
• Winter: Birds- Long-tailed tit

Public transport
The nearest train station is Beverley, from which it is a 20 minute walk to the nature reserve.

By car
On the southern outskirts of Beverley. Turn off at Keldgate onto the A164 at the double mini roundabout, signposted Cottingham and Humber Bridge. At the next roundabout turn left onto Woodmansey Mile, then right on to Lincoln Way. Park in the lay-by on the left where the road bends round. Walk across a paved path and the grass to the nature reserve.