Glossary

What this page is

Every word this platform uses that a newcomer would have to look up: the hydrology, the data-quality standard, the export formats and the handful of names the interface has of its own. One entry per idea, one or two sentences each, and a link to the page that treats it properly — the explanation lives in the section it belongs to, and this page is the index into it.

The same list is what draws the Words on this page line at the top of the health dashboard, the sensor list, the data-quality and rating-curve sections and the alert lists. There is one definition of each term in this product and it is the one below; if a page ever disagrees with this page, the page is wrong.

The terms

Twenty-odd entries run to several screens on a phone, and the “on this page” rail only knows about headings — so the terms index themselves, here, and each name jumps to its entry: Backfill · CEDEN · Data quality · Discharge · Extrapolating · Quality flag · HEC-DSS · In-app only · Machine-learning alert · No recipients · Observed property · Power law · Q · QARTOD · Rating curve · RDB · Views · Shift · Sonde · Stage · Station · Storage key · Suspect / Fail / ungraded · Telemetry · Quiet period · Weir / flume · Workbench · WQX.

Backfill

Computing or re-loading a stretch of record that is already in the past — rebuilding a discharge series after a curve changes, or importing older readings a logger held on to. It writes history, not new data. Read more.

CEDEN

California Environmental Data Exchange Network — the state submission format for water quality data. It needs a saved station and variable mapping before a file can be built. Read more.

Data quality

The section that grades readings, records manual flags and corrections, and keeps the audit trail behind them. It was called "QA/QC" in the navigation until 2026-09; both names mean this section, and one of them is an acronym nobody expanded. Read more.

Also written: QA/QC.

Discharge

How much water is going past: a volume per unit of time, such as ft³/s or m³/s. It is what a rating curve computes from stage. Read more.

Also written: flow.

Extrapolating

The sensor is reading a stage outside the range its rating curve was fitted for, so the discharge being published is an extension of the curve past its evidence rather than a reading of it. The health page says so as a warning; the number is still computed. Read more.

Quality flag

One verdict per reading, numbered the way IOOS QARTOD numbers them: Good (1), Suspect (3), Fail (4), Missing (9), or no code at all when nothing has graded it yet. Read more.

HEC-DSS

The US Army Corps of Engineers time-series database format, read by HEC-RAS and HEC-HMS. An export format here, not a storage format. Read more.

In-app only

A rule whose author declared that it should notify nobody. It still evaluates, still opens and resolves incidents, and still shows its state — it just never sends email or SMS. Grey, because it is a choice. Compare "no recipients", which is the same silence unasked for. Read more.

Machine-learning alert

A rule that learns what this sensor normally does — from its own history and the weather — and fires on what the model did not predict, rather than on a number you chose. One of the five alert kinds. Read more.

Also written: ML, Advanced (ML), Machine Learning Alerts, advanced.

No recipients

A rule with no email address and no phone number behind it, which was not declared deliberate. It is fully armed and structurally incapable of telling anyone, which is why it is drawn in amber rather than grey. Read more.

Observed property

What a variable measures, named from a standard vocabulary — water temperature, discharge, turbidity. A variable needs one, plus a recognised unit, before the standards endpoints and most export formats can carry it. Read more.

Power law

The usual shape of a stage–discharge rating: Q = C·(h − h₀)^b, where h is stage, h₀ the stage of zero flow, and C and b are fitted to measurements. A channel behaves like this over a range, not forever, which is why ratings are segmented. Read more.

Q

The hydrologist's symbol for discharge. A derived discharge series is named after the stage variable it came from with "_Q" on the end, and "Backfill Q" recomputes that series over the whole record. Read more.

QARTOD

Quality Assurance / Quality Control of Real-Time Oceanographic Data — the IOOS standard this platform grades readings against and publishes flag codes from. The tests are the standard's; the thresholds are yours. Read more.

Rating curve

The stated relationship between stage and discharge at one place: a fitted power law, a lookup table, a weir formula. It is what turns a depth record into a flow record. Read more.

RDB

The plain-text, tab-separated table format the USGS publishes and accepts. One of the export formats here. Read more.

Views

The per-sensor, per-variable configuration page: display labels, units, observed properties, which variables are plotted, whether a sensor is public, and which maps, dashboards and analytics pages it belongs to. The navigation called it "Settings" for two days in 2026-09 and the docs still say "the Settings page" in places; the permission category that governs it is labelled "Views" in the group permissions form. Read more.

Also written: Settings.

Shift

A dated correction added to stage before the rating is evaluated, for when the channel control moves — scour, a gravel bar, a rebuilt weir — but the shape of the rating still holds. Cheaper and more honest than refitting a curve for every disturbance. Read more.

Sonde

A multi-parameter water-quality instrument lowered into the water — typically temperature, conductivity, dissolved oxygen, pH and turbidity from one body. It appears here as one sensor with several variables. Read more.

Stage

How deep the water is, measured against a fixed datum by a pressure transducer or read off a staff gauge. It is what the instrument records; discharge is what most people want. Read more.

Also written: gauge height, depth.

Station

A named place with more than one instrument standing at it. The instruments share its coordinates, and it appears once in a picker rather than once per instrument. A sensor need not belong to one. Read more.

Also written: site.

Storage key

A sensor's permanent identity. Every reading, flag, correction, gap-fill, review lock and alert event is filed under it, it is assigned once when the sensor is first saved, and it never changes however often the sensor is renamed. The site code is the display name you can change; this is not. Read more.

Suspect / Fail / ungraded

The three quality verdicts a reader meets as counts. Suspect: a test says the value may be wrong — kept, plotted, look at it. Fail: a test says it is wrong — dropped from statistics, marked bad in exports. Ungraded: nothing has judged it yet, which is deliberately not the same as Good. Read more.

Also written: not evaluated.

Telemetry

How readings get from the instrument to here — cellular, LoRa, satellite, or a person with a laptop and a cable. "No telemetry" means the record arrives by upload rather than on its own. Read more.

Quiet period

How long a rule stays silent after it fires, so one long excursion pages once instead of every evaluation cycle. Shown on a card as "≥4h between alerts"; a rule with none says so in amber. Read more.

Also written: cooldown, time between alerts, hours between alerts.

Weir / flume

A structure built into a channel with a known, published stage–discharge relationship — a rectangular, Cipolletti or V-notch weir, a Parshall flume. Where one exists the rating is the structure's formula and its standard coefficient, not a fit. Read more.

Workbench

A full-window, one-sensor editing tool, as opposed to a list. There are three: the data-quality workbench, the rating-curve editor and the CEDEN mapping workbench. Each is reached from its section's landing page. Read more.

WQX

Water Quality Exchange — the US EPA's submission format, reached through the WQX web service. An export format here. Read more.