How to Identify Natural Water Boundaries

All queries or rectification requests relating to natural water boundaries should be referred to the Policy team.

What is a shifting, or natural, water boundary?

A shifting, or natural, water boundary is a boundary with a water feature that has evolved through nature such as a river, loch or the sea, rather than a man-made water feature such as an artificial loch within a housing or leisure development, or a drainage ditch. The term also includes the landward (high water mark, ordinary spring tides (HWMS)) and seaward (low water mark, ordinary spring tides (LWMS)) boundaries of the foreshore. In the same way that a natural water boundary has evolved and changed through natural processes in the past, it is likely to continue to evolve and change in the future.

Useful links

How to map natural water boundaries

Mapping seabed

How to tell if a boundary adjoining water is a natural water boundary

To establish if a boundary adjoining water is a natural water boundary, there are two initial points to check -

1. Is the water boundary natural?

It is sometimes difficult to establish if a water feature is natural or not without spending time researching that water feature; if there is doubt, the keeper's policy is to treat the water feature as natural.

Natural
Water feature has evolved through nature; for example, a stream. Change to boundary has been gradual and due to natural causes; for example, the gradual silting up of one bank and the gradual erosion of the opposite bank (alluvion).

Non-natural
Water feature is man-made; for example, a canal. Change to boundary has been sudden; for example, the collapse of a river bank during a flood or storm (avulsion). Change to boundary has been man-made; for example, straightening and culverting a stream under a new road, or reclaiming an area of land by in-fill (a deliberate act).

2. Is the legal boundary tied to the water boundary?

Where the text in the deed for extent expressly states that the plot is bounded by, or includes part of, the water feature, then the boundary is deemed to be "tied " to that water feature. For example,

- "bounded on the north by the medium filum (centre line) of the River Almond";
- "bounded on the south west & west by the high water mark"; or
- "bounded on the south by the northern bank of the Ale Water".

Action to take

Natural?	Tied?	SO1 action	RO2 action
Yes	Yes	Refer to a referral officer for instructions on how to map the boundary.	See Further Guidance page - How to Map Natural Water Boundaries.
Yes	No	Refer to a referral officer for instructions on how to map the boundary.	See Further Guidance page - How to Map Natural Water Boundaries.
No	No	Map to the extent shown on the deed plan. If this differs from the extent shown on the OS map, refer to a referral officer for instructions on how to map the boundary. If this results in a competition in title with an existing cadastral unit, refer to a referral officer to consider for rejection.	Map to the extent shown on the deed plan. If this differs from the extent shown on the OS map, map to the extent shown on the deed plan. If this results in a competition in title with an existing cadastral unit, refer to a referral officer to consider for rejection.
No	Yes	Refer to a referral officer for instructions on how to map the boundary.	Refer to a referral officer for instructions on how to map the boundary.