Dallas doesn't fold grading and drainage into a single all-purpose site development approval the way some Texas cities do. A land-development project here typically clears a City of Dallas grading permit and a separate paving/drainage permit, both reviewed against the region's shared iSWM criteria, while also coordinating with plat and site plan approval and, on the right parcel, Trinity River floodplain review. None of that is unusual for a Texas metro, but the specific combination — and the regional design manual underneath it — trips up engineers who assume Dallas works like Houston or Austin.
This guide walks through what triggers each Dallas permit, what iSWM actually is, how floodplain review layers in near the Trinity River corridor, and how to sequence grading/drainage approval against platting so you're not redesigning detention after the fact.
Do I need a separate grading permit in Dallas?
Yes — the City of Dallas issues a distinct grading permit for land-disturbing activity, separate from the paving and drainage permit that covers on-site storm infrastructure and pavement sections. In practice the two are usually pursued together for a land-development project, since you can't grade a site without also resolving how it drains, but they are reviewed as separate submittals with their own criteria. Confirm early with the city's development services staff which permit track applies to your scope, especially on sites where grading precedes final drainage design.
What offsite infrastructure issues come up during Dallas review?
Grading and drainage approval in Dallas often surfaces offsite requirements that aren't obvious from the parcel boundary alone — downstream drainage capacity, required channel or storm drain improvements, and water/wastewater capacity along the frontage. Because iSWM criteria evaluate a site's effect on the broader drainage system, not just on-site containment, a project that manages its own detention adequately can still be asked to fund or construct downstream improvements if the receiving system is already constrained. Screening for these offsite obligations during feasibility, rather than discovering them during permit review, is one of the more reliable ways to protect a Dallas project's budget and schedule.
What is iSWM and why does Dallas require it?
iSWM — integrated Stormwater Management — is the regional design criteria developed by the North Central Texas Council of Governments (NCTCOG) and adopted by Dallas and many surrounding North Texas municipalities. It sets the technical standards for stormwater quantity and quality controls, channel and storm drain design, and erosion and sediment control on land-development sites. Because iSWM is a shared regional manual rather than a one-off city ordinance, engineers working across multiple NCTCOG-member cities can generally design to one consistent criteria set — but always confirm which iSWM version and which local amendments Dallas has adopted, since municipalities can layer their own supplements on top of the base manual.
When does Trinity River floodplain review apply to my site?
If any part of your site lies within the FEMA-mapped Special Flood Hazard Area associated with the Trinity River or its tributaries, you'll need a local floodplain development permit in addition to grading and drainage approval, and work within the regulatory floodway generally requires an engineer-sealed no-rise certification. The Trinity River corridor runs through and around a significant portion of Dallas, so floodplain screening should happen at the earliest site-feasibility stage — before grading design, not after — since floodway constraints can reshape a site plan entirely. See our Texas site-civil permitting guide for how floodplain administration works at the state and local level.
How does grading/drainage permitting sequence with platting and site plan approval?
Grading and drainage permits generally follow, or run in parallel with, plat approval and any required site plan review, because the city wants street, utility, and drainage infrastructure locked before it authorizes land disturbance. Engineers who submit grading plans before plat comments are resolved often find themselves revising detention and outfall design after the fact — the safer sequence is to treat plat/site plan approval as the input to final grading and drainage design, not as a parallel track you can finalize independently.
What erosion and sediment control requirements apply during construction?
Beyond the permanent detention and water-quality controls sized under iSWM, active construction sites need temporary erosion and sediment control BMPs — silt fence, inlet protection, stabilized construction entrances, and sediment traps — consistent with iSWM's construction BMP criteria. If the site disturbs an acre or more (or is part of a larger common plan of development), that construction-phase control plan also has to satisfy the state's separate stormwater permit obligation under the TPDES Construction General Permit TXR150000 — city drainage approval does not substitute for TCEQ permit coverage, and the two run on independent tracks.
Who inspects grading and drainage compliance once construction starts?
Once a grading permit is issued, City of Dallas inspection staff verify that construction matches approved plans — final grades, drainage infrastructure, and installed BMPs — before the city will sign off on the improvements or release related holds tied to plat recordation. Separately, if the site is under TXR150000 coverage, the permittee is responsible for its own SWPPP inspection and recordkeeping obligations under the state permit; the city inspector checking iSWM compliance is not performing that state-required inspection for you. Keeping the two inspection regimes straight — and staffed — avoids a common gap where a site passes city grading inspection but is out of compliance with its own SWPPP documentation.
Dallas grading & drainage permits at a glance
| Permit / review | Governing criteria | When it applies |
|---|---|---|
| Grading permit | City of Dallas development code | Land-disturbing activity on the site |
| Paving / drainage permit | iSWM (NCTCOG) design criteria | On-site storm infrastructure, detention, pavement |
| Floodplain development permit | FEMA SFHA + local floodplain ordinance | Site within mapped Trinity River floodplain |
| Construction stormwater | TPDES Construction General Permit TXR150000 | ≥1 acre of disturbance (or larger common plan) |
The permits above cover the site itself, but don't treat frontage and offsite drainage as someone else's problem — a downstream capacity constraint uncovered mid-review is one of the most common sources of Dallas schedule slip, and it's far cheaper to resolve at feasibility than after grading plans are substantially complete.
Dallas rewards engineers who treat iSWM as the technical backbone of the project and platting/site plan status as the schedule backbone. Get floodplain screening done early if you're anywhere near the Trinity corridor, size detention and water quality to the currently adopted iSWM criteria, and keep the state TXR150000 obligation on its own track rather than assuming city approval covers it. For the grading fundamentals that apply regardless of city, see what is a grading permit.