Before They Build™
Public Beta · Edition 5 · Updated June 2026Help improve Before They Build — report errors, suggest features, or share feedback.

Companion Handbook · Environment

The Water & Wetlands Handbook

Drainage, stormwater, retention ponds, wetlands, and flooding — who regulates them, and what to ask.

Plate ICivic Handbook · Vol. I · companion volume

Before They Build

The Water & Wetlands Handbook

A Neighborhood Action Guide

Companion Handbook · Civic Handbook · Vol. I

Plate VII — Planning Office · maps, mylar, and the watershed
Plate VIIPlanning Office · maps, mylar, and the watershed
Project
Companion Handbook · Environment
Status
Companion handbook
Location
Bring to your kitchen table

Vol. I · Edition One · Generated June 19, 2026 · Private to this device · Not legal advice.

© 2026 Before They Build™. All rights reserved. Educational re-use permitted; see beforetheybuild.com/permissions.

In one paragraph

Why water is almost always the real question

A huge share of neighborhood projects come down to water. Where it falls, where it pools, where it flows, where it goes. Stormwater, drainage, retention ponds, wetland fills, and flood paths are usually decided by engineers and reviewed by agencies most neighbours have never heard of. They are also the easiest concerns to make specific — because water leaves evidence.

Vocabulary

The terms you'll hear, in plain words

  • Impervious surface. Anything water can't soak through — roofs, pavement, packed gravel.
  • Stormwater. Rain that runs off impervious surfaces instead of soaking in.
  • Detention pond. Holds stormwater temporarily and releases it slowly.
  • Retention pond. Holds water permanently. Sometimes called a "wet pond."
  • Wetland. Land where water sits at or near the surface long enough to grow specific plants. Federally defined.
  • Floodplain. Land that floods in a major storm. Mapped by FEMA. Insurance follows the map.
  • Riparian buffer. The vegetated strip along a stream or river. Often legally protected.

Who regulates this

The agencies that actually matter

  • U.S. Army Corps of Engineers. Section 404 wetland fills, work in navigable waters.
  • EPA + state environmental agency. Discharges, stormwater permits (NPDES), water quality.
  • State water resources / DNR. Streams, lakes, dam safety, water withdrawals.
  • County / municipal engineer. Local stormwater rules, retention sizing, plan review.
  • FEMA. Floodplain maps and flood insurance.
  • Local conservation district. Erosion control on construction sites.

See Who Handles What? for the full triage map.

Speak well

Questions that make a hearing record

  1. How much new impervious surface will this project add?
  2. Where exactly does the stormwater discharge?
  3. What is the design storm? (1-year, 10-year, 100-year?)
  4. Has the wetland delineation been verified by the Army Corps?
  5. Are any portions of the site in a mapped floodplain?
  6. What is the riparian buffer on the stream, and is it being reduced?
  7. Who is responsible for maintaining the retention pond — forever?
  8. What happens downstream of this site in a 100-year storm?
Water & Wetlands Handbook · Summary

Executive Summary

A huge share of projects come down to water — where it falls, where it pools, where it flows. Stormwater, drainage, retention ponds, and wetland fills are usually the easiest concerns to make specific, because water leaves evidence.

Three things to find in any plan

  1. The proposed impervious surface area — and how it compares to today.
  2. The stormwater management plan — where water goes, in what storm.
  3. Any wetland delineation or floodplain overlay on the site.
Water & Wetlands Handbook · §1

§1 — The vocabulary

Stormwater terms

  • Impervious surface — anything water can't soak through.
  • Detention pond — holds water briefly, releases slowly.
  • Retention pond — holds water permanently.
  • Design storm — the rainfall event the system is built for. Usually 10-year or 25-year.

Wetland and stream terms

  • Wetland delineation — the survey that defines the edge of a wetland.
  • Section 404 permit — Army Corps approval to fill a wetland.
  • Riparian buffer — the vegetated strip along a stream.
  • Floodplain — land that floods in a major storm. Mapped by FEMA.
Water & Wetlands Handbook · §2

§2 — Eight questions for the record

  1. How much new impervious surface will this add?
  2. Where exactly does the stormwater discharge?
  3. What is the design storm?
  4. Is the wetland delineation verified by the Army Corps?
  5. Are any portions of the site in a mapped floodplain?
  6. What is the riparian buffer — and is it being reduced?
  7. Who maintains the retention pond — forever?
  8. What happens downstream in a 100-year storm?
Water & Wetlands Handbook · §3

§3 — Evidence that holds up

Water leaves evidence. Photographs with date and a fixed reference point (a corner of a house, a utility pole) are accepted at almost every hearing.

What to photograph

  • The same spot before, during, and after rain.
  • Visible water lines on trees, fences, or foundations.
  • Sediment plumes leaving a construction site after a storm.
  • Erosion-control fencing that has failed.
  • Standing water that lasts more than 24 hours after rain stops.
Water & Wetlands Handbook · Worksheet

§4 — Observation log

DateTimeRain in last 24hWhat I sawPhoto #

Filing notes

Agency contacted
Person / phone
Reference #
Follow-up date

Related on this site

Before They Build

Civic Handbook · Vol. I · Edition One

Water & Wetlands Handbook · generated June 19, 2026

beforetheybuild.com/reports/community-guide

Printed June 19, 2026 · Reference ID ------

Private to this device. General information only — not legal advice. Confirm details with your local authority.

© 2026 Before They Build™. Educational use permitted. Not legal advice. Reprint or commercial use: beforetheybuild.com/permissions

Free during Public Beta · Suggested Support $2–3 · beforetheybuild.com/support