How to Map 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?

For help in identifying if your boundary is a shifting, or natural, water boundary, see Further Guidance page - How to identify natural water boundaries.

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 includes the landward (high water mark, ordinary spring tides (HWMS)) and seaward (low water mark, ordinary spring tides (LWMS)) boundaries of the foreshore, so also includes seabed plots that are bounded by the LWMS. 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. If a gradual, natural change occurs to a water boundary, any legal boundary that is tied to that water boundary will change with it.


How to map a shifting water boundary on the cadastral map

Is the water boundary natural?Is the water boundary tied?Does the depiction of the water boundary on the deed plan agree with the current OS map?how should the water boundary be mapped?
YesYesYesMap to the fullest legal extent supported by the titles submitted with the application as currently delineated on the OS map
YesYesNoMap to the fullest legal extent supported by the titles submitted with the application as currently delineated on the OS map
YesNo Yes Map to the extent shown on the deed plan
YesNoNoMap to the extent shown on the deed plan
NoYesYesMap to the extent shown on the deed plan
NoYesNoMap to the extent shown on the deed plan
NoNoYesMap to the extent shown on the deed plan
NoNoNoMap to the extent shown on the deed plan


1. Notes and plans references

Under the terms of the 2012 Act, the keeper is no longer required to provide a separate reference for a natural water boundary on the cadastral map, nor is she required to add a note relating to the natural water boundary to the property section of the title sheet. The keeper's policy is therefore, not to provide a separate reference or a descriptive note except in the following scenario:

  • If the natural water boundary is described as being a particular bank or the medium filum of a water course, but the OS map shows the water feature with a single line reference rather than a double line reference, then it is not possible for the keeper to show by the mapping alone what the fullest legal extent of the title is. The natural water boundary should be mapped to follow the single line OS feature, it should be arrowed & letter referenced in blue (preferably, although in particularly complex titles it may be more appropriate to use another colour), and a note should be added by the plans settler to the property section on the title sheet.

    • example note - The boundary between the points arrowed and lettered A and B in blue on the cadastral map is the medium filum of the Bow Burn.
    • example note - The boundary between the points arrowed and lettered X & Y in blue on the cadastral map is the south bank of the Daviot Water.
    • example note - The boundary between the points arrowed and lettered A and B in blue on the cadastral map is the low water mark, ordinary spring tides.


2. What is the fullest legal extent of a natural water boundary?

To establish the fullest legal extent of a natural water boundary, plans settlers should take account of both the deed plan and the written description in the deed for extent, and also the legal presumptions that further clarify the fullest legal extent. In the event of a contradiction between a legal presumption and the specific description in the titles, the titles will normally prevail. If there is any doubt about the fullest legal extent of a natural water boundary, the application should be referred to a referral officer for instructions.

The plot should be mapped to the fullest legal extent consistent with the titles. Please note that in Orkney and Shetland, different presumptions apply with regard to the foreshore and to titles bounded by the sea; please see Further Guidance page - Udal Law and the Foreshore in Orkney & Shetland.


Water FeatureLegal presumption on extent
foreshore
  • Where the landward title is "bounded by" the foreshore, the relevant boundary is the mean high water mark of ordinary spring tides (the line of which is marked "MHWS" on the OS map).
  • Where the landward title includes the foreshore, the relevant boundary is the mean low water mark of ordinary spring tides (the line of which is marked "MLWS" on the OS map). The lateral boundary of the foreshore between adjacent properties is a line drawn seawards from the end of the land boundary, perpendicular to a straight line drawn parallel to the average direction of the coast.
  • See Further Guidance pages Deed Plan Must Be Acceptable and Bounding Description of Property Must Be Acceptable for guidance on accepting descriptions of foreshore "ex adverso" the subjects defined in a deed.
river (tidal/estuary)
  • Where the landward title is "bounded by" the river, the relevant boundary is the river bank.
  • Where the landward title expressly includes the foreshore, the relevant boundary is the MLWS. The lateral boundary of the foreshore between adjacent properties is a line drawn from the end of the land boundary, perpendicular to a line representing the average direction of the medium filum (centre line) at low water.
  • See Further Guidance pages Deed Plan Must Be Acceptable and Bounding Description of Property Must Be Acceptable for guidance on accepting descriptions of foreshore "ex adverso" the subjects defined in a deed.
river (non-tidal)A title "bounded by" a river extends to the medium filum of that river.
burnsee river (non-tidal)
streamsee river (non-tidal)
island
  • In a non-tidal river or burn where the title boundary is the medium filum, an island in the middle of the water course will belong to adjoining owners in such proportion as the centre line of the water course bisects it. An island entirely on one side of the river or burn will belong to the near-side owner.
  • In a tidal river or in the sea, an island will belong to the Crown provided that the crown owns the alveus.
sea
  • In a deed granted by the Crown, foreshore is not included unless this is expressly indicated.
  • In other deeds, where the landward title is described as "bounded by" the sea, sea-beach or seashore, the presumption is that the foreshore is included.
  • In other deeds, where the landward title is described as "bounded by" the sea-flood or flood-mark, the presumption is that the foreshore is not included.
  • See Further Guidance page Description of Seabed Plot Must Be Acceptable for guidance on the requirements for deeds conveying seabed.
Loch (inland)Where the landward title is "bounded by" the loch, the ownership includes a segment of the solum of the loch, plotted by drawing perpendicular lines from the edges of the property to the centre point of the loch. In practice, this is difficult to achieve and there may often by a separate title which includes the solum - in which case, the landward title is plotted only to the edge of the land covered by the normal state of the water.


3. What do I do if the guidance tells me to map to the fullest legal extent of a plot as supported by the titles but that extent competes with an existing registered cadastral unit?

If the extent of the plot as defined on the deed plan competes with an existing registered cadastral unit, then the application should be referred to a referral officer to consider for rejection.


4. What do I do if the guidance tells me to map to the extent shown on the deed plan but the extent on the deed plan does not follow the features on the current OS map?

Under the terms of the 2012 Act, the duty is on the applicant to establish and identify the extent of the plot to be registered. If the boundary is not a tied, natural water boundary, then it should be treated like any other boundary and mapped to the extent defined on the deed plan. On occasion, this will mean plotting the line of a boundary rather than following a defined feature on the current OS map. If the full extent of the boundary can not be delineated accurately from the deed plan, then the application should be referred to a referral officer to consider for rejection.


5. What do I do if the guidance tells me to map to the extent shown on the deed plan but the extent on the deed plan competes with an existing registered cadastral unit?

If the extent of the plot as defined on the deed plan competes with an existing registered cadastral unit, then the application should be referred to a referral officer to consider for rejection.


6. What else do I need to be aware of when the plot I am mapping is a seabed plot?

There is a section of guidance, Mapping Seabed, that deals with this subject in more detail.

Where a seabed plot is bounded by land, the text in the deed may expressly state that the plot is "bounded by" the foreshore, or that "the boundary between the points A and B on the plan follows the MLWS". There is no requirement to provide OSGB36 coordinates for the landward boundary in these circumstances, provided an acceptable verbal description is contained in the deed. Cadastral units wholly within the SEA registration county will be created using the OPS tool, which does not show the MLWS as a defined feature. Where a seabed plot is described as being bounded by, or following, the MLWS, a request should be made to the GIS team who will add the necessary MLWS data to the OPS tool.