On this page
In this lesson
What you'll learn
- Explain the difference between erosion control and sediment control
- Choose erosion controls for flat areas, slopes and channels
- Apply planning practices that reduce exposed soil
- Know when temporary stabilization is required under the EPA CGP
Erosion is the detachment and movement of soil by rain, flowing water and wind. Erosion control practices protect the soil surface so it isn't detached in the first place. They're the first line of defense; sediment controls are the backup.
Plan to expose less soil
The best erosion control happens on the schedule:
- Phase the work so only the area being actively worked is exposed. Under the EPA CGP, sites that keep disturbance at 5 acres or less at any one time get a longer deadline (14 days) to complete stabilization.
- Preserve existing vegetation, especially along waterways, on steep slopes and in areas not needed for construction.
- Minimize steep slope disturbance. The CGP requires operators to minimize disturbance of steep slopes.
- Preserve native topsoil unless infeasible, and minimize soil compaction where vegetation will be established.
- Stabilize as you go, rather than waiting until the end of the project.
Surface covers
| Practice | How it works | Best for |
|---|---|---|
| Temporary seeding | Fast-growing grasses establish cover on areas idle for weeks or months | Flat to moderate slopes in growing season |
| Permanent seeding and sod | Final vegetative cover | Finished grades |
| Mulch (straw, wood fiber, hydromulch) | Protects soil from raindrop impact and holds seed and moisture | Seeded areas, short-term cover |
| Bonded fiber matrix / hydraulic mulches | Sprayed slurry that forms a protective layer | Steep or hard-to-reach slopes |
| Erosion control blankets and mats | Rolled products of straw, coconut fiber or synthetic netting, stapled in place | Slopes and channels. See the blankets guide |
| Plastic sheeting | Waterproof cover | Stockpiles and short-term emergency cover; increases runoff where it drains |
| Gravel, riprap and paving | Non-vegetative stabilization | Roads, outlets, permanent areas |
Slope and runoff practices
- Slope roughening and tracking: run tracked equipment up and down the slope so cleat marks run across it, creating small ridges that slow water.
- Terracing and slope breaks: interrupt long slopes so water can't build speed.
- Diversions and berms: route clean upslope water around disturbed areas.
- Slope drains: temporary pipes that carry concentrated flow down a slope.
- Check dams: small rock or fiber dams in swales that slow flow and reduce channel erosion.
- Velocity dissipation (riprap aprons, energy dissipators) at outlets, required by the CGP to minimize channel and streambank erosion near discharge points.
Dust control
The CGP requires minimizing dust on exposed soil through water application or other dust suppression techniques. Wind-blown dust settles into drainage paths and becomes stormwater sediment.
When temporary stabilization is required
Under the EPA CGP, stabilization must be initiated immediately (no later than the end of the next business day) in any area of exposed soil where construction has permanently ceased or will be temporarily inactive for 14 or more calendar days, and completed within:
- 14 calendar days after initiation, if no more than 5 acres are disturbed at one time; or
- 7 calendar days after initiation, if more than 5 acres are disturbed at one time, or if the site discharges to a sediment- or nutrient-impaired water or a Tier 2, 2.5 or 3 water.
More on deadlines and final stabilization in lesson 10.
Key takeaways
- Erosion control keeps soil from moving; it's more effective than catching sediment later.
- Phase work, preserve vegetation and topsoil, minimize steep slope disturbance and compaction.
- Use seeding, mulch, blankets, hydraulic products and non-vegetative covers matched to the slope and season.
- Slow water with roughening, slope breaks, diversions, check dams and outlet protection.
- Under the EPA CGP, start stabilizing idle areas immediately and finish within 14 or 7 days.
Knowledge check
Lesson 5 quiz: 8 questions
Choose one answer for each question, then select Check my answers. Score 80% or higher to pass. Your answers stay in your browser and are never saved.
Sources and official references
Last reviewed: October 25, 2026 · Free general education based on the Clean Water Act, EPA NPDES rules and the EPA Construction General Permit. Your governing permit (EPA, state, tribal or local) controls. This is not legal advice, not EPA-approved, and not a California QSP/QSD or other state credential, and it does not issue a certificate. Nothing you enter on this page is saved or sent.