usgs-water-mcp-server

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  <h1>@cyanheads/usgs-water-mcp-server</h1>
  <p><b>Query real-time and historical water data from ~8,000 USGS stream gages and groundwater wells via MCP. STDIO or Streamable HTTP.</b>
  <div>7 Tools • 2 Resources</div>
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**Public Hosted Server:** [https://usgs-water.caseyjhand.com/mcp](https://usgs-water.caseyjhand.com/mcp)

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---

## Tools

Five tools for querying USGS water data, plus two for SQL analytics over the DuckDB-backed canvas dataframes that `water_get_series` and `water_find_sites` materialize:

| Tool | Description |
|:-----|:------------|
| `water_list_parameters` | Static lookup of well-known USGS parameter codes with names, units, and domain. No network call. |
| `water_find_sites` | Find USGS monitoring sites by bounding box, state, county, or HUC watershed. Filter by site type and parameter availability. Large match sets spill to DataCanvas. |
| `water_get_readings` | Get the latest instantaneous values (~15 min real-time) for up to 100 USGS sites. |
| `water_get_series` | Get a time series of daily or instantaneous values for a site over a date range. Large ranges spill to DataCanvas. |
| `water_get_conditions` | Get current hydrologic conditions ranked against the full period-of-record percentile statistics. |
| `water_dataframe_describe` | List tables and columns staged on a DataCanvas by `water_get_series` or `water_find_sites`. |
| `water_dataframe_query` | Run a read-only SQL SELECT against the time-series and site tables staged by `water_get_series` and `water_find_sites`. |

### `water_list_parameters`

Static lookup of well-known USGS parameter codes — no network call, instant response.

- Discover that `00060` = Discharge (ft³/s), `00065` = Gage height (ft), `00010` = Temperature (°C), `72019` = Depth to water level (ft), and more
- Filter by thematic domain: `streamflow`, `groundwater`, `temperature`, `meteorological`, `water-quality`, or `all`
- Use this first — parameter codes are required by every other water tool

---

### `water_find_sites`

Discover USGS monitoring sites before calling data tools — all other tools require a site number.

- Geographic scoping: bounding box (`"west,south,east,north"` decimal degrees), 2-letter state code, bare 5-digit FIPS county code (e.g. `51013`), or HUC watershed code — either a 2-digit major HUC (`02`) or an 8-digit minor HUC (`02070008`), the only two lengths NWIS accepts
- Site type filtering: `ST` (stream), `GW` (groundwater well), `LK` (lake/reservoir), `SP` (spring), and more
- Parameter filter: only return sites that have data for a specific parameter code — comma-separate to require several (e.g. `00060,00065`)
- Data type filter: require sites with real-time (`iv`), daily (`dv`), or groundwater (`gw`) data
- Returns site number, name, coordinates, type, state/county/HUC codes, and drainage area (expanded mode only) — altitude is included in both modes when USGS records it
- Bounded result set: capped at 500 sites inline, with a `truncated` flag and `upstreamTotal` (the full upstream count) so an oversized query never overflows the response
- **DataCanvas spillover:** when the result is truncated and `CANVAS_PROVIDER_TYPE=duckdb` is set, the full match set is staged to a DuckDB-backed canvas — the response includes `canvas_id` and `table_name` to retrieve every match past the 500 cap via `water_dataframe_query`. Without DataCanvas, narrow the query with additional filters (county, HUC, bbox, parameter, data type) to bring the result under the cap

---

### `water_get_readings`

Get the latest instantaneous (~15 min) values for one or more USGS monitoring sites.

- Batch up to 100 site numbers in a single call
- Accepts any parameter code discoverable via `water_list_parameters`
- Configurable lookback period via ISO 8601 duration (e.g. `PT2H` = last 2 hours, `P7D` = last 7 days)
- Returns per-site, per-parameter records with timestamp, value, unit, and provisional/approved qualifier
- Bounded by design: each series carries its 10 most recent records, with `totalValues` reporting how many the period actually held and `truncated` flagging the cap. Use `water_get_series` when you need the full series
- Partial batches are explicit: requested sites NWIS returns no data for are named in `missingSites` rather than dropped silently
- Groundwater depth available via `parameterCd=72019` (the legacy `gwlevels` endpoint was decommissioned November 2025 — use the IV service instead)

---

### `water_get_series`

Get a historical time series for a site and parameter over a date range.

- Daily values (DV service, one value per day) or instantaneous values (IV service, ~15 min resolution)
- Returns site name, parameter name, unit code, and time-ordered value records with qualifiers
- **DataCanvas spillover:** large date ranges (>500 records) automatically spill to a DuckDB-backed canvas when `CANVAS_PROVIDER_TYPE=duckdb` is set — response includes `canvas_id` and `table_name` for follow-up SQL via `water_dataframe_query`
- Without DataCanvas, returns the most recent 500 records with a `truncated` flag and `totalRecords` count
- Supports chaining: pass a prior `canvas_id` to append data to an existing canvas

---

### `water_get_conditions`

Get current hydrologic conditions placed in full historical context.

- Fetches the current IV reading and the full daily percentile table in parallel
- Classifies the reading: `record-high` (≥ p95), `above-normal` (p75–p95), `normal` (p25–p75), `below-normal` (p10–p25), `low` (p05–p10), `record-low` (< p05)
- Pairs each class with a `percentileLabel` spelling out the threshold — `record-high` and `record-low` mark percentile-of-record extremes, not verified all-time records, and the label says so where the class name does not
- Ranks against the observation's own calendar day, so a reading near midnight is not compared against the neighboring day's percentiles
- Discloses the granularity approximation in `comparisonBasis`: the reading is instantaneous while the percentiles are approved daily-mean values, so the class is a "how unusual is this" ranking — not a flood-stage or drought determination, which need authoritative thresholds this tool does not fetch
- Validates `site` and `parameterCd` at the schema edge; a well-formed value NWIS still rejects surfaces as the typed `invalid_request` reason rather than an opaque upstream error
- Gracefully degrades when historical context is missing: returns the current reading with `historicalContext: null` and a `historicalContextStatus` saying why — `no_record` (new/short record), `no_matching_day` (no row for the date), or `unavailable` (stat call failed — transient and retryable, kept distinct from a sparse record)

---

### `water_dataframe_describe` / `water_dataframe_query`

In-conversation SQL analytics over the dataframes that `water_get_series` and `water_find_sites` materialize on a DuckDB-backed canvas — time-series tables from the former, full site match sets from the latter.

**Workflow:**
1. Call `water_get_series` with a large date range, or `water_find_sites` with a query that matches more than 500 sites — when DataCanvas is enabled, the response includes `canvas_id` and `table_name`
2. Call `water_dataframe_describe` with the `canvas_id` to confirm the table schema — series tables carry `date_time`, `value`, `qualifiers`, `site_number`, `parameter_cd`, `unit_code`; site tables carry `site_number`, `site_name`, `site_type`, `latitude`, `longitude`, `huc_cd`, and the expanded fields
3. Call `water_dataframe_query` with the `canvas_id` and a SELECT statement to run aggregates, filter, or join

Read-only by default — only SELECT statements are permitted. Results are capped at 10,000 rows; a query matching more comes back with `truncated: true`. Requires `CANVAS_PROVIDER_TYPE=duckdb` in the server environment.

## Resources and prompts

| Type | Name | Description |
|:-----|:-----|:------------|
| Resource | `usgs-water://site/{siteId}` | Site metadata: name