Lapväärtinjoki (Isojoki)
2 monitoring stations within this area in Finland, holding 20,727 values between 1970 and 2026. An area that drains to one outlet, not a single channel. The gauges below are within it and sit on different watercourses inside it.
The monitoring network within this area
Hydrionis holds 20,727 values from 2 gauges within it. Discharge is a property of a gauge and its reach, not of this drainage area, so this page reports the network and its records rather than a single figure.
How low, how high and how variable this gauge runs
A hydrograph says what happened; these say how often. Read off Perus's whole daily record between 1980 and 2026, they describe the shape of the record rather than any day in it — and they belong to this gauge and its reach, not to this drainage area.
These are the largest daily means, not flood peaks. A peak lasting hours is averaged across a whole day here, so the true instantaneous maximum on the same day was higher — sometimes far higher on a fast-responding catchment. Flood frequency work needs a publisher's own instantaneous series; Hydrionis holds one for 2,236 American gauges and not for this one, so the two are never drawn together. A water year the gauge did not substantially cover produces no value at all rather than a low one.
View the data behind this chart
| Period | Perus (m³/s) |
|---|---|
| 1980 | 164 |
| 1981 | 140 |
| 1982 | 138 |
| 1983 | 131 |
| 1984 | 89.0 |
| 1985 | 130 |
| 1986 | 129 |
| 1987 | 98.0 |
| 1988 | 96.0 |
| 1989 | 64.0 |
| 1990 | 74.0 |
| 1991 | 71.0 |
| 1992 | 105 |
| 1993 | 74.0 |
| 1994 | 97.0 |
| 1995 | 76.0 |
| 1996 | 77.0 |
| 1997 | 68.0 |
| 1998 | 122 |
| 1999 | 108 |
| 2000 | 104 |
| 2001 | 65.0 |
| 2002 | 107 |
| 2003 | 51.0 |
| 2004 | 96.0 |
| 2005 | 83.0 |
| 2006 | 117 |
| 2007 | 80.0 |
| 2008 | 74.0 |
| 2009 | 87.0 |
| 2010 | 109 |
| 2011 | 107 |
| 2012 | 199 |
| 2013 | 75.0 |
| 2014 | 94.0 |
| 2015 | 93.0 |
| 2016 | 57.0 |
| 2017 | 80.0 |
| 2018 | 58.0 |
| 2019 | 105 |
| 2020 | 101 |
| 2021 | 106 |
| 2022 | 74.0 |
| 2023 | 147 |
| 2024 | 142 |
| 2025 | 71.0 |
The longest record here
Annual means computed by Hydrionis from the published daily record, drawn only for years with at least 300 days held. They summarise this gauge's own record and say nothing about any other watercourse in this area.
View the data behind this chart
| Period | Perus (m³/s) |
|---|---|
| 1980 | 11.1 |
| 1981 | 18.3 |
| 1982 | 14.7 |
| 1983 | 10.1 |
| 1984 | 15.5 |
| 1985 | 11.4 |
| 1986 | 14.8 |
| 1987 | 12.2 |
| 1988 | 15.4 |
| 1989 | 14.3 |
| 1990 | 9.30 |
| 1991 | 12.3 |
| 1992 | 16.6 |
| 1993 | 11.3 |
| 1994 | 11.6 |
| 1995 | 13.7 |
| 1996 | 10.3 |
| 1997 | 12.2 |
| 1998 | 16.0 |
| 1999 | 12.2 |
| 2000 | 14.2 |
| 2001 | 11.6 |
| 2002 | 8.21 |
| 2003 | 9.78 |
| 2004 | 12.9 |
| 2005 | 13.2 |
| 2006 | 12.3 |
| 2007 | 14.3 |
| 2008 | 15.7 |
| 2009 | 8.44 |
| 2010 | 8.67 |
| 2011 | 13.7 |
| 2012 | 17.7 |
| 2013 | 12.1 |
| 2014 | 11.1 |
| 2015 | 15.6 |
| 2016 | 11.8 |
| 2017 | 12.1 |
| 2018 | 8.15 |
| 2019 | 11.2 |
| 2020 | 19.0 |
| 2021 | 11.0 |
| 2022 | 13.8 |
| 2023 | 15.2 |
| 2024 | 17.1 |
| 2025 | 12.5 |
Every gauge Hydrionis holds within this area
| Gauge | Measures | Values | Record |
|---|---|---|---|
| Perus | mean river flow | 17,075 | 1980–2026 |
| Perus | mean river flow | 3,652 | 1970–1979 |
How these gauges were attached to this water
Assigned by the publisher to a numbered basin Every gauge here is assigned to this drainage area by its own publisher, which issues the area an official code — 37. A drainage area is not a river: it contains the tributaries as well as the main channel, and a gauge in it may be on any of them.
| Gauge | Evidence | Established |
|---|---|---|
| Perus | Stated by the publisher on the record this gauge’s observations came from. | With the observations |
| Perus | Stated by the publisher on the record this gauge’s observations came from. | With the observations |
What this record holds
Hydrionis decides which waters get a page, and which of those are offered to search, from what is actually held rather than from how the page reads. Five signals are counted; this record has 2 of them, which makes it a profile, not indexed.
| Signal | Held | Counts |
|---|---|---|
| Gauges holding a real record | 2 | no |
| Years spanned | 57 | yes, 20 or more |
| Values held | 20,727 | yes, 1000 or more |
| Distinct measurements | 1 | no |
| Publishers measuring it | 1 | no |
| Official identifiers | 1 | recorded, not counted |
Use this data
Use this data
- Machine-readable JSON
/api/v1/observations/by-subject/fi-syke-3700300.json - How to cite this, and who you must credit
- How these figures were produced
- Request this at a different scale, format or geography
Attribution and citation
Attribution you are required to give
These are conditions of the licences the underlying data is published under. They are obligations to the publishers, not to Hydrionis, and they apply to you directly whether or not you mention Hydrionis at all.
Contains data from the Finnish Environment Institute (Syke), licensed under CC BY 4.0.
Suggested citation for Hydrionis
Hydrionis (2026), Lapväärtinjoki (Isojoki) gauge records, accessed 2026-10-05, hydrionis.com/waters/finland-lapvaartinjoki-isojoki/
Cite Hydrionis where you rely on the compilation, the normalisation, the eligibility judgements or a chart. Where you use an unmodified published value, the publisher’s attribution is the one that is required; crediting Hydrionis as well is welcome and is not something Hydrionis can require of you.
Where these figures come from
Source: Syke — Hydrologiarajapinta — Finnish national hydrological archive, 3700300. Licence: Open — attribution required (attribution required).
Method: Daily discharge exactly as the Finnish Environment Institute publishes it. Syke computes the daily value from its own measurement and rating curves; Hydrionis does not recompute it, because a mean derived from whatever sub-daily data happens to be exposed would be a different statistic under the same name. Values Syke flags as possibly erroneous are not stored.
One of these values (under 1%) is interpolated by Syke rather than measured, and is marked as such in its own archive. Station in the Lapväärtinjoki (Isojoki) main drainage basin, Peruksen a sub-basin. Discharge is a property of this gauge and this reach, not of the river as a whole.
Retrieved 1 October 2026.