Datasets:

zer0contextlost
/

waterwatch-runoff

level stringclasses 5 values	huc_id stringlengths 2 8	name stringlengths 3 41 ⌀	states stringclasses 295 values	wy int32 1.9k 2.03k	runoff_mm float64 -21.68 28.6k	rank int64 1 127	n_years int64 1 127	percentile float64 0.78 99.2 ⌀	class int64 0 8	n_sites int32 1 45 ⌀	max_weight float64 0 1 ⌀
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,900	619.803	64	127	50	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,901	648.093	52	127	59.38	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,902	740.092	22	127	82.81	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,903	619.431	65	127	49.22	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,904	541.369	100	127	21.88	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,905	476.664	114	127	10.94	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,906	577.027	84	127	34.38	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,907	590.952	75	127	41.41	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,908	726.432	30	127	76.56	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,909	552.37	93	127	27.34	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,910	579.978	82	127	35.94	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,911	413.482	122	127	4.69	2	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,912	729.77	27	127	78.91	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,913	689.635	41	127	67.97	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,914	654.407	50	127	60.94	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,915	496.547	106	127	17.19	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,916	651.937	51	127	60.16	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,917	753.845	19	127	85.16	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,918	566.108	87	127	32.03	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,919	714.125	31	127	75.78	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,920	758.853	16	127	87.5	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,921	646.888	53	127	58.59	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,922	616.238	68	127	46.88	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,923	549.644	97	127	24.22	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,924	553.589	91	127	28.91	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,925	464.924	116	127	9.38	3	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,926	626.764	62	127	51.56	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,927	529.889	102	127	20.31	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,928	841.433	8	127	93.75	7	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,929	615.951	70	127	45.31	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,930	484.139	111	127	13.28	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,931	453.204	118	127	7.81	3	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,932	528.974	103	127	19.53	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,933	644.49	55	127	57.03	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,934	582.989	81	127	36.72	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,935	590.871	76	127	40.62	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,936	687.558	42	127	67.19	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,937	642.698	56	127	56.25	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,938	677.055	43	127	66.41	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,939	631.894	60	127	53.12	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,940	584.166	80	127	37.5	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,941	420.207	121	127	5.47	3	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,942	493.237	107	127	16.41	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,943	537.371	101	127	21.09	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,944	492.478	108	127	15.62	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,945	705.116	35	127	72.66	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,946	594.928	72	127	43.75	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,947	623.922	63	127	50.78	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,948	485.127	110	127	14.06	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,949	468.42	115	127	10.16	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,950	455.226	117	127	8.59	3	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,951	738.631	23	127	82.03	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,952	731.176	26	127	79.69	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,953	645.952	54	127	57.81	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,954	773	14	127	89.06	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,955	758.433	17	127	86.72	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,956	589.69	78	127	39.06	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,957	389.228	125	127	2.34	2	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,958	711.304	33	127	74.22	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,959	545.081	99	127	22.66	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,960	788.416	13	127	89.84	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,961	630.175	61	127	52.34	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,962	504.022	105	127	17.97	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,963	633.175	59	127	53.91	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,964	554.788	90	127	29.69	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,965	342.906	127	127	0.78	1	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,966	407.765	124	127	3.12	2	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,967	551.934	94	127	26.56	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,968	572.166	85	127	33.59	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,969	636.17	58	127	54.69	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,970	728.463	29	127	77.34	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,971	556.544	89	127	30.47	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,972	660.537	47	127	63.28	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,973	886.744	4	127	96.88	7	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,974	759.825	15	127	88.28	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,975	552.384	92	127	28.12	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,976	803.369	12	127	90.62	7	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,977	657.857	48	127	62.5	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,978	755.489	18	127	85.94	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,979	704.558	36	127	71.88	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,980	489.336	109	127	14.84	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,981	551.068	96	127	25	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,982	729.114	28	127	78.12	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,983	737.168	24	127	81.25	6	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,984	916.761	2	127	98.44	7	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,985	372.658	126	127	1.56	2	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,986	593.312	74	127	42.19	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,987	585.002	79	127	38.28	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,988	481.756	112	127	12.5	4	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,989	615.97	69	127	46.09	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,990	665.589	45	127	64.84	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,991	701.207	39	127	69.53	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,992	590.792	77	127	39.84	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,993	551.692	95	127	25.78	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,994	669.677	44	127	65.62	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,995	452.051	119	127	7.03	3	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,996	868.151	5	127	96.09	7	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,997	713.427	32	127	75	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,998	709.759	34	127	73.44	5	null	null
2	01	New England Region	CN,CT,MA,ME,NH,NY,RI,VT	1,999	546.859	98	127	23.44	4	null	null

End of preview. Expand in Data Studio

waterwatch-runoff: US watershed runoff 1900-2026, continuing USGS WaterWatch

Monthly and water-year runoff for every gaged HUC8 watershed in the conterminous US, plus HUC2/4/6 regions and a national total, computed from USGS streamgage records with the method USGS WaterWatch used. Each value carries WaterWatch's rank, percentile and condition class. Version 1, November 2026.

Data: huggingface.co/datasets/zer0contextlost/waterwatch-runoff · Code and notes: github.com/zer0contextlost/waterwatch-runoff

Not affiliated with or endorsed by the U.S. Geological Survey.

Live gage map: zer0contextlost.github.io/waterwatch-runoff, the 7/14/28-day streamflow percentile maps WaterWatch used to publish, rebuilt nightly. Same class as WaterWatch's archived 7-day maps for 91% of 823 gages (99% within one class).

Why this exists

USGS retired WaterWatch on 2026-02-26. Its HUC runoff maps and tables (monthly, quarterly and annual runoff for every hydrologic unit back to 1901) went with it. The replacement pages on Water Data for the Nation give statistics per streamgage; for watershed runoff USGS points users to an example notebook in its hyswap package that computes it for a handful of HUC8s. WaterWatch's own runoff download had already stopped at water year 2023.

The gages still report every day. This dataset runs the calculation for all of them.

Method

Following WaterWatch (Jian, Wolock & Lins 2008, USGS Fact Sheet 2008-3031, and the USGS catalog entry "Water Watch HUC Runoff"):

For each water year (or calendar month), keep streamgages with a complete daily record, and only gages whose delineated basin area is within 25% of the NWIS drainage area.
Basin runoff = mean daily flow / drainage area, assumed uniform over the basin.
Weight each basin-HUC pair by (share of basin in the HUC) x (share of HUC in the basin).
HUC runoff = weighted mean over overlapping basins.

Basin-HUC intersections come from the table USGS ships with hyswap (huc_props_tbl_conus.csv, 19,031 gaged basins, 2,074 HUC8s). Daily discharge (parameter 00060, daily mean) comes from the USGS Water Data API. Where one basin covers a HUC almost exactly (weight > 0.81) it is used alone; otherwise basins inside the HUC plus the smallest basin containing it are used, as hyswap does, falling back to all overlapping basins when neither exists.

HUC2/4/6 and the national total are area-weighted means of their HUC8 values. WaterWatch built those levels from its own basin intersections, so ours are an approximation at those levels.

Rank 1 is the wettest period on record. Percentile = (1 - rank/(n+1)) x 100 over all periods with a value (months ranked against the same calendar month), which is the convention in WaterWatch's own download. Classes: 1 record low, 2 below 5th, 3 5th-10th, 4 10th-25th, 5 25th-75th, 6 75th-90th, 7 above 90th, 8 record high. Percentile and class are blank where a HUC has fewer than 10 periods.

Validation

Compared with WaterWatch's published water-year 2008 HUC8 runoff (its download as archived by the Internet Archive on 2016-12-19), for 1,951 of its 2,038 HUC8s:

	value
runoff correlation	0.98
median absolute difference	3.4%
median bias	+0.1%
within 5% / 10% / 25%	56% / 67% / 79%
percentile, median gap	3.1 points
class, exact / within one	76% / 97%
US total, WY2008	255 mm (WaterWatch 246 mm)

The largest relative misses are near-zero-runoff HUCs in the arid West and HUCs represented only by a large downstream basin. An exact match isn't possible: WaterWatch's own basin delineations were not published, gage records have been revised since 2016, and the hyswap table is newer. Per-HUC comparison: data/validation_wy2008_vs_waterwatch.csv.

Water year 2026

Water year 2026 (October 2025 to September 2026) was the third driest since 1951 for the conterminous US, on a fixed set of 1,919 HUC8s with values every year: 182 mm, after 1988 (172 mm) and 1977 (177 mm). Series: data/us_fixed_set_wy1951.csv.

HUC2	region	runoff mm	rank (1 = wettest)	percentile
03	South Atlantic-Gulf	210	127 of 127	0.8
13	Rio Grande	7	127 of 127	0.8
14	Upper Colorado	38	125 of 127	2.3
02	Mid Atlantic	301	122 of 127	4.7
08	Lower Mississippi	215	121 of 127	5.5
01	New England	435	120 of 127	6.2
06	Tennessee	354	117 of 127	8.6
04	Great Lakes	357	51 of 127	60.2

April 2026 was the lowest April on record for the South Atlantic-Gulf region. This is consistent with NWS drought statements from the spring (record-low flows on the Santa Fe River and near-record lows on the Suwannee; Georgia in D4 drought from 2026-04-14) and with record-low Upper Rio Grande snowpack. 2026 values use provisional USGS data and will move as records are approved.

Files

file	rows	contents
`data/huc_runoff_wy.parquet` (+ `.csv.gz`)	293,042	water years 1900-2026, HUC8/6/4/2 and US
`data/huc_runoff_month.parquet`	3,552,991	months 1899-10 to 2026-10
`data/site_runoff_wy.parquet`	508,907	per-gage water-year runoff used as input
`data/us_fixed_set_wy1951.csv`	76	national series on a fixed HUC8 set
`data/validation_wy2008_vs_waterwatch.csv`	2,039	per-HUC comparison with WaterWatch

Columns: level (2/4/6/8/US), huc_id, name, states (WBD), wy or month, runoff_mm, rank, n_years, percentile, class, n_sites and max_weight (HUC8 only: gages used and the largest single weight).

Caveats

Rollups and the US total average only HUC8s that have a value in that period. Early years have far fewer (785 HUC8s in 1901, about 2,000 since 1950), so use a fixed HUC8 set for long-run comparisons.
Values before 1930 rest on a sparse gage network; WaterWatch carried the same warning.
Runoff here is gaged streamflow per unit area. Regulated rivers (reservoirs, diversions) are included as measured, as in WaterWatch.
Conterminous US only. Alaska, Hawaii and Puerto Rico are not in the hyswap intersection table.

Reproduce

Clone DOI-USGS/hyswap into ref/hyswap (for the intersection table) and run src/fetch_wbd.py (HUC names and areas). src/fetch_dv.py 1900 2027 pulls daily discharge for all gages in the intersection table (a free USGS Water Data API key makes this hours instead of days); src/site_stats.py reduces it to complete periods; src/huc_from_stats.py --method hybrid builds the HUC tables; src/validate.py compares with WaterWatch. Details in NOTES.md.

License

Code: MIT. Data: CC BY 4.0. Inputs are USGS public-domain data.

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