About Stormwater Atlas

Stormwater Atlas is actively under development, not a finished reference product. Manuals are added from a public queue; many records are automated first drafts flagged for quality review. Treat the site as a living dataset — always confirm critical values against the linked official PDF.

Currently maintained on GitHub.

Stormwater Atlas is a research and comparison tool. Use it to find what different jurisdictions' manuals say about design storms, water-quality volume methods, peak-flow approaches, BMP categories, and related criteria — without reading hundreds of PDFs. Each value is paired with a cited excerpt and a link to the official agency document.

It is not adopted regulation and not a substitute for the controlling manual, ordinance, or engineer of record. Always open the linked official PDF before design or permitting decisions.

Use the homepage map and table to find a federal, state, county, or city manual. Open a jurisdiction to see design storms, water-quality methods, BMPs, and other fields — each with a cited excerpt and a link to the official PDF or agency page.

Browse federal drainage guidance (FHWA hydraulic circulars) separately from adopted state and local manuals. The U.S. Stormwater Practice Synthesis is an 18-chapter research draft with practice notes, criteria guidance tables, and curated citations — provisional language for discussion, not a design manual or adopted practice. Data freshness follows the latest npm run export:data / site build.

The same database is published as static JSON. No API key, no signup. Fetch over HTTPS from any script, agent, or notebook.

Discovery file for crawlers: /llms.txt

Base URL: https://stormwateratlas.com. CORS is open for /data/*.

You may link to Stormwater Atlas without asking first. A short credit is appreciated but not required. Prefer the project name in public copy; individual maintainer credit is optional.

Suggested attribution line (project only):

Stormwater Atlas — national index of stormwater design manual criteria with cited excerpts. https://stormwateratlas.com

Suggested blurb for resource pages:

Stormwater Atlas is a free, open reference for comparing stormwater design manual requirements across U.S. federal, state, county, and city jurisdictions. Key fields are paired with verbatim excerpts and links to official agency PDFs. The database is under active development — use it as a research aid and always verify against the current official document.

Many records show a Needs review badge or an orange banner on the manual page. This is an extraction quality flag, not a public volunteer program.

Records are flagged when automated extraction from the source PDF had low or medium confidence, ambiguous wording, missing fields, or citation checks that did not fully pass. The flag means: compare the cited excerpt to the official PDF before you rely on this field.

How to check a record yourself:

1. Open the manual page and note any populated design-criteria fields.
2. Read the quoted excerpt under each field and confirm it supports the value shown.
3. Open the linked official PDF or agency page and verify against the current adopted text (edition, date, and section).
4. Check Fields not found in document — those criteria were not located in the extracted text and may still exist elsewhere in the manual.

There is no in-site correction form yet. To report a fix, open an issue on GitHub with the manual slug, field name, and the correct excerpt or page reference from the official document.

Use the homepage filter Needs review only to browse flagged records, or filter by Confidence: High for extractions that passed without the review flag.

Fetch the index

curl https://stormwateratlas.com/data/manuals.json

Fetch one manual

curl https://stormwateratlas.com/data/manuals/austin-tx-ecm.json

Filter in JavaScript

const res = await fetch("https://stormwateratlas.com/data/atlas.json");
const { manuals } = await res.json();

// Texas manuals that list a 100-year design storm
const tx100 = manuals.filter(
  (m) =>
    m.document_metadata.state_code === "TX" &&
    m.design_criteria.design_storm_return_periods_years.includes(100)
);

console.log(tx100.map((m) => m.document_metadata.jurisdiction_name));

Prompts for an AI agent

• “Fetch /data/atlas.json and compare design storm return periods for Texas vs California state manuals.”
• “Which manuals list bioretention (or rain gardens) under approved BMP categories? Cite the evidence excerpt.”
• “Load /data/manuals/seattle-wa.json and quote the source text for the water quality volume method.”
• “From the index, list every municipality in Florida with confidence: high.”

Extractions are a research aid, not a substitute for the controlling manual, ordinance, or engineer of record. Always open the linked official document before design or permitting decisions.

See Needs review flag for what the quality badges mean and how to verify a record.