Paragraph 7

Northern Ireland

To determine the morphological conditions applicable to a lake or any part thereof, the Department must assign the hydromorphological characteristics of the lake or part thereof as being of the type specified in column 1 of Table 9 below which corresponds to the applicable measurements specified in columns 3 and 4 of that Table.

Table 1

Criteria for identifying the types of river to which the dissolved oxygen, ammonia and biochemical oxygen demand standards for rivers apply

Site Altitude	Alkalinity (as mg/l CaCO₃)
	Less than 10	10 to 50	50 to 100	100 to 200	Over 200
Under 80 metres	Type 1	Type 2	Type 3	Type 5	Type 7
Over 80 metres	Type 1	Type 2	Type 4	Type 6	Type 7

Table 2

Final typology for dissolved oxygen, ammonia and biochemical oxygen demand in rivers
Column 1	Column 2
Upland and low alkalinity	Types (1+2), 4 and 6
Lowland and high alkalinity	Types 3, 5 and 7

Table 3

Criteria for identifying types of river to which morphological conditions apply

Type	Characteristics
Bedrock channel	Normally high altitude	Channel cuts down laterally	May have waterfalls and/or cascades	Bedrock substrate
Cascade Step Pool	Normally high altitude	Channel cuts down	Both turbulent and tranquil flows	Cobble and boulder substrate
Pool-riffle-glide	Normally medium altitude	Often not confined within a valley	Slightly meandering	Pebble and cobble substrate
Meandering	Normally low altitude	Flow laminar and would naturally interact with floodplain	Meandering	More fines than other substrates

Table 4

Criteria for identifying types of river to which the river flow standards apply

Column 1	Column 2	Column 3	Column 4
Type	Standard Average Annual Rainfall mm (period 1961-1990)	Base Flow Index (BFI)	Catchment area (km²)
A1	< 810.5	< 0.715	Any
A1	< 810.5	≥ 0.715	≥ 251.8
A2	< 810.5	≥ 0.715	< 251.8	≤ 100 (A2 headwaters) > 100 (A2 downstream)
A2	≥ 810.5 and < 1413	≥ 0.7495	Any	≤ 100 (A2 headwaters) > 100 (A2 downstream)
B1	≥ 810.5 and < 1155	≥ 0.3615 and < 0.7495	< 267.4
B2	≥ 810.5 and < 1413	≥ 0.3615 and < 0.7495	< 267.4
C2	≥ 1155 and < 1413	≥ 0.3615 and < 0.7495	< 267.4
C2	≥ 1413	≥ 0.3615	≥ 32.33
D2	≥ 1413	≥ 0.3615	< 32.33
D2	≥ 810.5	< 0.3615	Any

Table 5

Geological categories to which total phosphorus, phytoplankton and phytobenthos standards for lakes apply

Geological category	Annual mean alkalinity (micro-equivalents per litre)
Low alkalinity	< 200
Moderate alkalinity	200 – 1000
High alkalinity	> 1000
Marl	> 1000

Table 6

Depth categories to which total phosphorus standards for lakes apply

Depth category	Mean depth (metres)
Very shallow	< 3
Shallow	3 – 15
Deep	> 15

Table 7

Colour categories to which total phosphorus standards for lakes apply

Colour category	Platinum (mg/l)
Humic	> 30
Non humic	≤ 30

Table 8

Geological characteristics used to identify lake types to which lake level standards apply

Categories
Column 1	Column 2
Peat	Non-Peat
mean water colour ≥90 hazen units; or	mean water colour <90 hazen units; or
≥75% of solid catchment area comprised of peat	<75% of solid catchment area comprised of peat

Table 9

Hydromorphological characteristics used to identify lake types to which morphological conditions apply

Column 1	Column 2	Column 3	Column 4
¹ Morphological Impact Assessment System
Type	Lake-MImAS¹ code	Mean Depth	Alkalinity
Low Alkalinity Very Shallow	P/L-vS	<4m	< 20 mgl^-1 CaCO₃
Low Alkalinity Shallow/Deep	P/L-ShD	>4m	< 20 mgl^-1 CaCO₃
Moderate Alkalinity Very Shallow	MA-vS	<4m	20 – 100 mgl^-1 CaCO₃
Moderate Alkalinity Shallow/Deep	MA-ShD	>4m	20 – 100 mgl^-1 CaCO₃
High Alkalinity Very Shallow	HA/M-vS	<4m	> 100 mgl^-1 CaCO₃
High Alkalinity Shallow/Deep	HA/M-ShD	>4m	> 100 mgl^-1 CaCO₃