Tool · free
BMWP-PL / ASPT calculator
Tick the units found in your sample - the calculator sums the scores (BMWP) and works out the average score per taxon (ASPT).
lake Not on the river list - this entry comes from the list for lakes and dam reservoirs (App. II/III)
No entries match your search.
Tick at least one unit.
How we calculate
BMWP is the sum of the scores of all ticked units (each counts once, regardless of abundance). ASPT (Average Score Per Taxon) is BMWP divided by the number of ticked units - it depends less on sample size and compares sites better. Higher values mean an assemblage with a larger share of pollution-sensitive taxa.
What the list is made of: 88 + 30
The list holds 118 scored entries because the GIOŚ handbook carries it in two versions. 88 entries form the RIVER list (App. IV, naming after the SI JWoda system) - the one that feeds ASPT_PL inside MMI_PL. The other 30 come from the broader list for LAKES and DAM RESERVOIRS (App. II/III): among others Osmylidae, Psephenidae, Spongillidae, Lestidae, Libellulidae, Spionidae, Nereidae, Muscidae, Tabanidae, Bryozoa and Araneae, plus the split of Heptageniidae into two genus-level entries. The calculator marks them "lake" and lets you filter them out.
Which sampling the scores refer to: The scores of the RIVER LIST are calibrated to multi-habitat sampling (MHS): 20 sub-samples from habitats covering more than 5% of the bed, 1.25 m² in total, a hand net per PN-EN 16150:2012 (25 cm frame, 500 µm mesh). In the laboratory at least 5 sub-samples and at least 350 individuals are sorted. Note: this protocol comes from the chapter on rivers and that is the only place we verified it. Entries marked „jez." sit in the chapters on lakes and dam reservoirs, which have their own sampling procedure - we do not extend this description to them.
What this calculator does not do
Polish state monitoring no longer assesses the ecological status of rivers with BMWP-PL alone. The index in force is MMI_PL, in which ASPT_PL is one component (weight 0.334). The result must not be presented as a WFD ecological status class.
We deliberately do NOT publish class boundaries for BMWP-PL/ASPT: they depend on the biocenotic river type and enter classification through MMI_PL, not through ASPT alone.
Source of the scores: Kolada A. (red.), 2020. Podręcznik do monitoringu elementów biologicznych i klasyfikacji stanu ekologicznego wód powierzchniowych. Aktualizacja metod. Biblioteka Monitoringu Środowiska, GIOŚ, Warszawa. ISBN 978-83-950881-2-4, rozdz. „Makrozoobentos w rzekach”, Załącznik IV, s. 160 - „Lista rodzin wskaźnikowych makrozoobentosu, uwzględniana przy wyliczeniach BMWP_PL/ASPT_PL (za Kownacki i in., 2004, zmienione, nazewnictwo wg SI JWoda)”; 88 pozycji; rozdz. „Makrozoobentos w zbiornikach zaporowych”, Załącznik II, s. 173-174 (identyczna tabela: rozdz. „Makrozoobentos w jeziorach”, Załącznik III, s. 293-294) - „Standardowe wartości do obliczania BMWP_PL (za Kownacki i in., 2004, zmienione)” (accessed 2026-08-19).
Frequently asked questions
Why does the list hold more than the 88 families of the methodology?
Because the GIOŚ handbook carries the BMWP-PL list in two versions. The river list (Appendix IV) holds 88 entries and it is the one that feeds ASPT_PL in river monitoring. The list for lakes and dam reservoirs (Appendix II/III) is broader - it adds Osmylidae, Spongillidae, Lestidae, Nereidae, Bryozoa or Araneae among others, and splits Heptageniidae into two genus-level entries. The calculator shows both layers and marks the entries that are not on the river list.
Does ticking a "lake" entry spoil the result?
No - the score comes from the same source, only from a different appendix. You do need to know what you are counting: if you are working up a river sample in the state-monitoring convention, switch on the "River list only" filter. For a lake or reservoir sample, keep the full list.
Why does Heptageniidae appear twice?
Because the lake/reservoir list goes below family level here: the genera Epeorus and Rhithrogena score 8 points, the remaining genera of that family score 6. The river list scores the whole family at 8. With the „river list only" filter on you see a single row without the genus narrowing, because that is what App. IV looks like. In the full list, tick the entry that matches your identification; if a lake sample holds both genus groups, tick both - the calculator counts them as two units and says so under the result.
Does BMWP give a water quality class?
Not from BMWP alone and not in this calculator. Class boundaries depend on the biocenotic river type and, in Polish monitoring, enter the assessment through the multimetric MMI_PL, in which ASPT_PL is one component. The number on this page is a comparative value, not a WFD ecological status class.
One index says nothing about the direction of change
The value of BMWP shows only in a series: the same site, successive seasons. In LimnoLog you record BMWP and ASPT as your own indicators against a site and a date, and the results line up into a time series by themselves.
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