Ms Mary Gurrie:

Leitrim is covered on the red map because it either has a nitrates level that has increased, which is unlikely, or it has a water body that is trophic.

By that, I mean rivers, lakes or estuaries. We sometimes just think of estuaries as being trophic, but that is not the case. The trophic level applies to any water body, including rivers and lakes. Leitrim has been identified because there is a water body in Leitrim that is either newly trophic or is at risk of growing worse.