fix(waterdata): accept the latest-continuous method_category queryable

NEWS.md

@@ -1,3 +1,5 @@
+**10/29/2026:** `waterdata.get_latest_continuous()` accepts `method_category`, a column USGS added to the `latest-continuous` collection in October 2026; `get_continuous()` has accepted it since 09/22/2026. It is the RLMS method category code (`STNRD`, `LMTUS`, `EXPER` or `UNKWN`) for the method in effect over an observation's interval, returned on every record and null for time series that have not been categorized. It could already be passed through `**queryables`; it is now a documented, keyword-only parameter.
+
 **10/16/2026:** **Bug fix:** the time-zone table behind the `*DateTime` columns that `waterdata.get_samples()` and `wqp.get_results()` append, and behind `utils.format_datetime()`, now follows the code lists those services use: the USGS NWIS time-zone list (Samples, and the USGS records that the Water Quality Portal passes through) and the WQX TimeZone domain (Water Quality Portal). USGS records write American Samoa as `ZP-11`, which was missing, so every timed American Samoa row from `get_samples()`, and every timed USGS American Samoa row from `get_results()`, had a `NaT` datetime; it is now UTC-11. 39 other codes from the two lists that used to become `NaT` now resolve, among them the remaining `ZP*` offsets, `IDLW`, `IDLE`, `NZT`, `SWT`, and the retired WQX codes `AHST` and `YST`. **Behavior change:** codes that the table read with a different meaning from the USGS list now take the USGS meaning: `CAST` (+9:30), `CCT` (+8), `EASST` (+11), `EAST` (+10), `NFT` (-3:30), `NZDT` (+13), `WAST` (+7), and `WAT` (-1). `FJST` is now UTC+13. Where the two lists disagree, WQX wins: `SST` stays American Samoa (UTC-11), the meaning the Water Quality Portal returns, and `BST` is UTC-11.
 
 **10/15/2026:** **Bug fix:** the `ActivityStartDateTime` and `Activity_StartDateTime` columns that `wqp.get_results()` and `waterdata.get_samples()` append, and the `datetime` column of `utils.format_datetime()`, read the time-zone code `GST` as Gulf Standard Time (UTC+4). The USGS time-zone codes and the WQX TimeZone domain both define `GST` as Guam Standard Time (UTC+10), so a sample collected on Guam at 10:00 local time was placed at 06:00 UTC instead of 00:00 UTC. `GST` is now UTC+10, and `HDT` (Hawaii-Aleutian Daylight Time, UTC-9), a USGS code that was missing from the table, now resolves instead of becoming `NaT`.

dataretrieval/waterdata/time_series.py

@@ -496,6 +496,8 @@ def get_latest_continuous(
     filter_lang: FILTER_LANG | None = None,
     convert_type: bool = True,
     max_rows: int | None = None,
+    *,
+    method_category: str | Iterable[str] | None = None,
     **queryables: Any,
 ) -> tuple[pd.DataFrame, BaseMetadata]:
     """Get only the most recent observation of each continuous time series.
@@ -533,7 +535,7 @@ def get_latest_continuous(
         The columns to return from the query. Available
         options are: geometry, id, time_series_id, monitoring_location_id,
         parameter_code, statistic_id, time, value, unit_of_measure,
-        approval_status, qualifier, last_modified
+        approval_status, qualifier, method_category, last_modified
     time_series_id : string or iterable of strings, optional
         A unique identifier representing a single time series, corresponding to
         the id field in the time-series-metadata endpoint.
@@ -564,6 +566,12 @@ def get_latest_continuous(
         sensor may have been impacted by ice or whether values were estimated.
         Matches observations whose qualifiers are exactly these, in this order:
         ``"ICE"`` matches ``["ICE"]`` but not ``["ESTIMATED", "ICE"]``.
+    method_category : string or iterable of strings, optional
+        The RLMS method category code for the method in effect over the
+        observation's interval: "STNRD" (standardized, with known uncertainty
+        and full QA/QC), "LMTUS" (limited use: a modified or externally
+        sourced method), "EXPER" (experimental), or "UNKWN" (unknown).
+        Null for time series that have not been categorized.
     value : string or iterable of strings, optional
         The value of the observation. Values are transmitted as strings in
         the JSON response format to preserve precision.

tests/data/waterdata_ogc_fixtures.json

@@ -499,18 +499,19 @@
      ],
      "type": "Point"
     },
-    "id": "2ccf9208-befe-4486-9ce2-0c0e4cff7127",
+    "id": "333a18ac-e09b-422a-a38c-454f70454475",
     "properties": {
      "approval_status": "Provisional",
-     "last_modified": "2026-08-07T18:55:07.672769+00:00",
+     "last_modified": "2026-10-29T13:54:19.532512+00:00",
+     "method_category": "UNKWN",
      "monitoring_location_id": "USGS-06904500",
      "parameter_code": "00065",
      "qualifier": null,
      "statistic_id": "00011",
-     "time": "2026-08-07T18:45:00+00:00",
+     "time": "2026-10-29T13:45:00+00:00",
      "time_series_id": "b36569a0067443ac9425e850a3ac7baa",
      "unit_of_measure": "ft",
-     "value": "1.59"
+     "value": "0.13"
     },
     "type": "Feature"
    },
@@ -522,18 +523,19 @@
      ],
      "type": "Point"
     },
-    "id": "862137bb-d9e8-4e99-85a7-be2d82f5daa7",
+    "id": "26e6625d-342a-4a98-8225-98d84524eefa",
     "properties": {
      "approval_status": "Provisional",
-     "last_modified": "2026-08-07T18:55:14.240081+00:00",
+     "last_modified": "2026-10-29T13:54:13.767087+00:00",
+     "method_category": null,
      "monitoring_location_id": "USGS-06904500",
      "parameter_code": "00060",
      "qualifier": null,
      "statistic_id": "00011",
-     "time": "2026-08-07T18:45:00+00:00",
+     "time": "2026-10-29T13:45:00+00:00",
      "time_series_id": "627c17455f9e4a4286e1d75dde4d8470",
      "unit_of_measure": "ft^3/s",
-     "value": "535"
+     "value": "75.4"
     },
     "type": "Feature"
    }

tests/data/waterdata_queryables.json

@@ -306,6 +306,7 @@
     "hydrologic_unit_code",
     "id",
     "last_modified",
+    "method_category",
     "minor_civil_division_code",
     "monitoring_location_id",
     "monitoring_location_name",

tests/waterdata_test.py

@@ -1172,6 +1172,9 @@ def test_get_latest_continuous(httpx_mock):
     assert df.columns[-1] == "latest_continuous_id"
     assert df["time"].dtype.name.startswith("datetime64[")
     assert "UTC" in df["time"].dtype.name
+    # One fixture series is categorized and one is not.
+    assert df["method_category"].iloc[0] == "UNKWN"
+    assert pd.isna(df["method_category"].iloc[1])
     assert hasattr(md, "url")
     # Multi-value params go in one CQL2 POST when the request fits.
     sent = _items_requests(httpx_mock, "latest-continuous")