2.2 Uses Of Mtr - Planet WGSW-24010 User Manual

2.2 Uses of MTR

The MTR method can be used to give a qualitative assessment of whether a river site is impacted
by eutrophication and (for physically similar sites) downstream changes in trophic status. It
should not be used to compare the trophic status of physically dissimilar sites, nor should it be
used to make comparisons between the trophic status of different rivers unless the rivers are the
same type.
The principal application for which the method has been developed and tested is to assist in the
designation of identified reaches as SA(E)s under the UWWTD (2.3). The methodology has
been used extensively by the Environment Agency for this purpose.
The method should be equally applicable to the assessment of other point-sources of nutrients,
but is not yet fully proven for other applications (2.4). Use of the system to date, however, is
encouraging. For example, macrophyte surveys using MTR and the method of Haslam (DoE
Standing Committee of Analysts 1987) have been used in Northern Ireland to indicate the
location of eutrophication problems and to monitor trends in the trophic status of rivers (Oliver
& Hale 1996). A combined approach using macrophyte, invertebrate and ecotoxicological work
upstream and downstream of key discharges has been found to be useful, with the potential
addition of the Trophic Diatom Index (TDI, 3.1.2). English Nature have used the MTR together
with the Nature Conservancy Council macrophyte classification to examine the impact of
discharges from small- and moderate-sized sewage works on small rivers (eg Southey 1995).
Although there was no clear relationship between the two sets of results and percentage
reductions in MTR score downstream of discharges were not great, possibly due to high
phosphate-loading upstream, it is felt that the MTR shows much potential and that it is useful to
use both systems when analysing changes of macrophyte floras over time.
R&D Technical Report E38 8