Why Fall Is the Best Time to Install a Grassed Waterway

Fall, right after harvest, is the best time for grassed waterway installation in Indiana. The crop is off, the ground is usually firm enough for heavy equipment, and the gullies from this year are easy to see. Building the waterway now means it is shaped and protected before spring rains hit fields in Decatur County and across central Indiana.

Key Takeaways

• A grassed waterway is a shaped channel planted with grass that carries runoff off a field at a speed that does not cause erosion (USDA NRCS).
• Fall, after harvest, is the most practical time to build one in Indiana because fields are open and erosion channels are easy to see.
• Indiana waterways are designed for the runoff from a 10-year, 24-hour storm and are typically 20 to 60 feet or more wide (Indiana NRCS).
• A new waterway needs temporary cover such as straw mulch or erosion netting right after construction until the grass is established.
• Indiana NRCS advises no mowing between April 1 and August 15 to protect nesting wildlife.

What Is A Grassed Waterway And Why Does My Field Need One?

I’m Cameron Jordan with Jordan Excavating LLC. Every fall we drive past fields around Greensburg, Rushville and Shelbyville with the same problem: a ditch cutting down the middle of a draw where water runs every spring. That channel gets deeper each year, it eats ground and it beats up equipment.

The USDA NRCS defines a grassed waterway as a shaped or graded channel planted with suitable vegetation that carries surface water at a non-erosive speed to a stable outlet. In plain terms, we reshape the draw into a wide, shallow channel and grow thick grass in it. The grass slows the water down and the roots hold the soil.

According to Indiana NRCS, the main sign you need one is concentrated flow: water that keeps running through the same spot and moving residue and soil even after you have tried cover crops or other fixes.

Why Is Fall The Best Time For Grassed Waterway Installation In Indiana?

We can build a waterway in other seasons, but fall lines up best for most farms:

• The crop is off. We can work the draw without running over standing corn or beans, and you do not lose a season of yield.
• You can see the problem. Rills and gullies tend to form in the same place each year. Right after harvest, the damage from this year’s storms is fresh and easy to mark.
• The ground is usually firmer. Fall often gives us drier soil than spring, which means less compaction and cleaner shaping.
• It is ready before spring rain. A waterway shaped and covered in fall is in place when spring runoff comes, instead of the gully getting another year deeper.
• Crews have room on the calendar. Spring is the busiest time for site work. Booking in fall usually gets you on the schedule faster.

When Should The Grass Be Seeded?

Timing the seed matters as much as timing the dirt work. Purdue and University of Illinois Extension put the best window for establishing cool-season grass at August 15 to September 15 in the northern half of Indiana and September 1 to 30 in the southern half. They call spring seeding “difficult and often unsuccessful” and list dormant seeding, from about Thanksgiving to March, as another option.

That gives a fall waterway two paths:

• Early fall: if harvest comes off early, we shape the channel and seed it while there is still time for the grass to start.
• Late fall: we shape the channel, protect it with temporary cover, and the seed goes in as a dormant seeding or in spring, depending on the plan for your field.

Either way, Indiana NRCS says a nurse crop and temporary cover, such as straw mulch or erosion control netting, should go in right after construction. That protects the bare soil until the permanent grass takes hold.

How Is A Grassed Waterway Designed And Built?

Every waterway is sized for the water that drains to it. According to Indiana NRCS, waterways in Indiana are designed to handle peak runoff from a 10-year, 24-hour storm. Across the state, that storm brings about 3.7 to 4.7 inches of rain, or roughly 2 to 3 inches of runoff depending on cover, land use and soils. Indiana waterways usually run from about 20 feet to 60 feet or more wide.

Here is how a typical job goes with our crew:

• Walk the field. We look at the draw, the outlet and where the water comes from.
• Clear the path. Brush, stumps and trees come out of the waterway route.
• Strip and save topsoil so it can go back on the finished channel.
• Shape the channel to the planned width, depth and slope, usually a wide, shallow shape equipment can cross.
• Spread topsoil, seed and cover with mulch or netting to protect it through the first season.

If the waterway is part of a cost-share contract, we build to the design your NRCS or soil and water conservation district office provides.

How Do You Take Care Of A New Waterway?

A waterway is not a one-time fix. The NRCS lists a minimum expected life of 10 years, and how long it lasts depends on care. NRCS notes that most damage comes from equipment or herbicides, and it is avoidable.

• Do not plant end rows along the sides of the waterway.
• Cross it only when the ground can take it, and lift tillage tools when crossing.
• Keep herbicide drift off the grass.
• Mow to keep brush and trees out, but not between April 1 and August 15, per Indiana NRCS, to protect nesting wildlife.
• Inspect after big storms and fix thin or eroded spots right away.

Who Builds Grassed Waterways Near Greensburg And Decatur County?

Jordan Excavating LLC is a licensed, insured, BBB-accredited contractor based in Greensburg. We have been working farms in central and southeast Indiana for more than 10 years, and agricultural work is a big part of what we do, including grassed waterways, farm ponds, fence line clearing and field drainage.

You can read more about our grassed waterway service, see our fence line clearing and farm pond work, or check the 20-county service map on our Services page. If you farm near Greensburg, our Decatur County page covers our local work.

Frequently Asked Questions

These are the questions farmers ask us most about waterways.

When is the best time to install a grassed waterway in Indiana?

For most Indiana farms, the best time is fall, right after harvest. The crop is off, the ground is usually firmer, and you can see where gullies formed this year. Shaping the channel in fall and protecting it with temporary cover gets it ready to carry spring runoff instead of cutting deeper.

How wide is a grassed waterway?

According to Indiana NRCS, grassed waterways in Indiana typically range from about 20 feet to 60 feet or more in width. The size depends on how much water drains to that spot, the soil type and the grass used. They are designed to carry runoff from a 10-year, 24-hour storm without eroding.

Can I drive farm equipment across a grassed waterway?

Yes, when ground conditions allow. NRCS designs waterways with a wide, shallow shape so equipment can cross without damaging the channel or the machine. Avoid planting end rows along the sides, keep herbicide off the grass, and repair any ruts or thin spots quickly so water does not start a new channel.

When should a grassed waterway be mowed?

Indiana NRCS advises against mowing between April 1 and August 15 so nesting wildlife is not disturbed. Outside that window, mowing keeps a healthy stand and stops brush and trees from taking over, which would cut the waterway’s capacity. If your waterway is under a cost-share contract, check its rules first.

Is there cost-share help for grassed waterways in Indiana?

Often, yes. Indiana NRCS points landowners to their local USDA Service Center, and there is one in every Indiana county. NRCS and Farm Service Agency staff there can explain technical help and financial programs. Ask before construction starts, because most programs need approval and a design before any dirt is moved.

Get A Free Waterway Estimate

If you watched water cut through a field this year, now is the time to fix it before spring. We will walk the field with you and give you a clear, written estimate.

Request a free estimate or call (812) 371-6999.

Written by Cameron Jordan, owner of Jordan Excavating LLC, serving central and southeast Indiana for 10+ years. Last updated: October 23, 2026.

Sources: Indiana NRCS, Ask the Indiana NRCS Expert: Grassed Waterways; USDA NRCS, Grassed Waterway (412) Overview; Purdue Extension AY-3-W, Establishing Turfgrass Areas From Seed.