Mobile, AL Drainage Guide: Permits, 811, Soils (2026)

Updated October 25, 2026. This guide is general information, not legal or engineering advice. Rules change, so confirm with the agency listed before you start work.

Quick reference

Topic	What to know	Source
Rainfall	About 66.3 inches a year over a 30-year period; July and August wettest	Wikipedia (NOAA data)
Rainiest city	Ranked first in the contiguous 48 states in a 2007 study	LiveScience
Elevation	About 10 feet downtown to about 211 feet at Mobile Regional Airport	Wikipedia
Soils	Malbis series: perched water table late fall to early spring, 30 to 50 inches down	USDA NRCS
City inlets	More than 40,000; report clogs to Mobile 311	FOX10, City of Mobile
Land disturbance	Simpler single-family path under 4,000 sq ft with no drainage change; Tier 2 at 1 acre	Build Mobile
Flood zone fill	No-Rise certification from an Alabama PE in the SFHA, unless on the simpler path	Build Mobile
Before digging	Alabama 811: free, at least 2 full working days ahead, marks good 20 working days	Alabama 811
Licensing	Home builder license for residential work over $10,000	Alabama HBLB

Why do Mobile-area yards hold water?

Mobile gets a lot of rain. Wikipedia's summary of NOAA data puts the city's average at about 66.3 inches a year over a 30-year period, with July and August the wettest months, and a 2007 study by WeatherBill, reported by LiveScience, ranked Mobile the soggiest city in the contiguous 48 states at about 67 inches. Mobile sits at the head of Mobile Bay, and its elevation ranges from about 10 feet on Water Street to about 211 feet at Mobile Regional Airport, so the lowest neighborhoods have little fall toward the water.

The soil adds to it. The Malbis series, a widespread soil on the Southern Coastal Plain of Alabama, Florida, Louisiana, Mississippi and Texas, was described from a site near Fairhope across the bay. USDA describes it as moderately well or well drained, with plinthite in the subsoil, moderately slow permeability in its lower layers and a perched water table each year from late fall through early spring at 30 to 50 inches. Water stalls on the slower layer and spreads sideways, which is the situation a French drain is built for.

What does the City of Mobile handle?

The city's Public Services Stormwater Department monitors flood-prone spots and clears catch basins, culverts and drain pipes, often with vacuum trucks. Its director told FOX10 in June 2026 that the city has more than 40,000 inlets and crews can't watch them all, so residents are asked to report clogged drains through 311. Mobile 311 handles non-emergency requests by phone (dial 311 inside city limits), through the Mobile 311 app or online, and the city says to call 911 for a flooding emergency.

The city is also working on its larger creeks. Its Langan Lake project stabilizes the banks of Twelve Mile Creek and dredges Langan Park Lake, both of which drain into Three Mile Creek and Mobile Bay, with flood control listed among its goals.

What permits can apply inside Mobile?

The Engineering Department reviews land disturbance permits through Build Mobile. Its permit guide sets out a simpler single-family residential path for single-family and duplex lots when land disturbance is under 4,000 square feet, new impervious area is under 4,000 square feet and the work doesn't change natural drainage patterns. Larger projects fall into permit tiers, with Tier 2 starting at an acre of disturbance. In a Special Flood Hazard Area, no fill is allowed without a "No-Rise" certification from an Alabama professional engineer unless the project qualifies for the simpler path. The city's flood zone development permit lists filling, grading and watercourse alteration among the work it covers. A separate Urban Forestry permit is needed to remove or relocate heritage trees 18 inches or more in diameter on private property.

What about Saraland, Semmes and the county?

Each city has its own office. Saraland's land disturbance permit application calls for a site grading and drainage plan with an erosion control plan, stormwater calculations where applicable, and no encroachment within 10 feet of wetlands. Semmes is a separate city incorporated in 2011. In unincorporated areas like Tillmans Corner, Mobile County runs a Phase II MS4 stormwater program that covers construction-site runoff and illicit discharges, and its Stormwater Management office takes reports of stormwater runoff problems.

Do I have to call 811?

Yes. Alabama 811 says to contact it any time you plan to dig, including for landscaping, and its services are free. Requests must go in at least two full working days before excavation, not counting the day of notice, and marks are valid for 20 working days.

Does a drainage contractor need a license?

Alabama's Home Builders Licensure Board requires a license when the cost of residential construction, repair or improvement work exceeds $10,000. The law doesn't mention drainage or landscaping specifically, so whether a given job is covered depends on its scope. Ask the contractor which license, if any, applies, and look it up on the board's website. Wiring a sump pump is electrical work with its own rules.

Questions to ask a drainage contractor

Where will the water end up, and could it affect my neighbors?
How much fall does the drain have from start to outlet?
Does this job need a land disturbance, flood zone or tree permit?
Who will submit the Alabama 811 request, and when?
Which license, if any, applies, and do you carry insurance?
How can the system be cleaned out later, and what's under warranty?

Common questions

Will the City of Mobile fix drainage in my yard?

The city's Stormwater Department maintains public inlets, culverts and pipes. Drainage on your own lot is up to you. Report clogged public drains through Mobile 311.

Can I add fill to raise my yard in Mobile?

Check first. In a Special Flood Hazard Area, fill needs a No-Rise certification from an Alabama professional engineer unless the project qualifies for the city's simpler single-family path.

How much notice does Alabama 811 need?

At least two full working days before you dig, not counting the day you submit. The service is free and the marks are good for 20 working days.

Mobile County, Alabama yard drainage guide (2026)