Only one of Northern Ireland's 21 larger lakes has "good" water quality, according to a new report.
The lake is Lough Scolban, in County Fermanagh, although it isn't listed by name in the report published by the Department of Agriculture, Environment and Rural Affairs (DAERA).
Water in the remaining 20, which are 50 hectares or larger, is of "moderate" standard or worse.
The report rates conditions from bad to high.
The analysis shows that there has been a deterioration in the the water quality of Northern Ireland's lakes since previous surveys in 2015 and 2018.
Back then, five of the 21 lakes were classified as "good".
The report says there has been a "significant decline" in lake water quality in the intervening years.
Traditionally the main pressure points on water quality are nutrient run-off from farming and waste water treatment.
During analysis rivers and lakes are measured against 40 parameters, for things like nutrients, fish, invertebrates, chemical composition and physical condition.
The parameter with the lowest result sets the overall water quality standard.
'Unlikely to hit target'
Our 450 rivers are not included in this survey, but previous work has shown that only around a third have "good" water quality.
The department has already conceded that it's unlikely to hit a 2021 target to have 70% of rivers in good condition.
Under EU water quality rules, it's the responsibility of the Northern Ireland Environment Agency to classify rivers and lakes, prevent a deterioration in water quality and where practicable to improve it.
Management is done through River Basin Management Plans which run on a six year cycle with the next ones due in 2021.
The EU rules have been transposed into domestic law and will continue to apply after Brexit unless amended by legislation.