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Methodology & Reading the Data

How Sigap Mentaya assesses river water quality.

What is on this site?

Each semester, DLH Kotawaringin Timur samples water at several points along the Mentaya river, tests it in the lab, and assigns a quality status (Meets standard, Lightly / Moderately / Heavily polluted). Sigap Mentaya publishes those official results together with a Pollution Index (PI) value we recompute from the available parameters, so you can see trends.

The four status classes

Classification follows the Pollution Index (PI) method in KepMenLH 115/2003 against PP 22/2021 class II river water standards.

  • Meets standardWater meets class II standard — suitable for recreation, fisheries, and irrigation. Not for direct drinking.
  • Lightly pollutedSome parameters exceed the threshold. Generally still safe for bathing and washing, but avoid swallowing water and treat it before household use.
  • Moderately pollutedWater quality has declined. Avoid prolonged contact, bathing, and eating fish caught here. Household water sources must be thoroughly treated.
  • Heavily pollutedPoor water quality. Do not use for water activities, fish consumption, or household water. Please report any change in color, smell, or dead fish.

How the Pollution Index (PI) is computed

For each measured parameter (pH, BOD, COD, TSS, DO, etc.), we compute a "sub-index" — how far the value is from the class II standard. The final PI is the RMS of the maximum sub-index and the average sub-index. Ranges: 0–1 meets standard, 1–5 lightly polluted, 5–10 moderately polluted, above 10 heavily polluted.

PP 22/2021 class II standards

Class II is designated for recreation, fisheries, and irrigation — not direct drinking water. Most Mentaya river segments are classified class II by regional regulation.

A note on peat rivers

The Mentaya is a Central Kalimantan peat river — naturally acidic (pH 4–6) due to humic acids from peat lands. A pH below the class II range (6–9) is often not a pollution indicator here but a natural characteristic. Sigap Mentaya flags this on pH cards.

Limitations and honesty

The data shown comes from DLH lab results — sampling is per semester, so day-to-day conditions may differ. PI is computed from the parameters available; those not tested are not included. If you see a change in the field (smell, color, dead fish), please report it.

Regulations & references

  • PP 22/2021 on the Implementation of Environmental Protection and Management, Attachment VI
  • KepMenLH 115/2003 on Guidelines for Determining Water Quality Status
  • DLH Kotawaringin Timur — primary data source