LEPA vs LESA packages: what changes for sector monitoring

If you've swapped a span from overhead impact sprinklers to a LEPA or LESA drop package, the wetted pattern under that pivot changed even though the geometry on paper didn't. That matters the first time someone pulls up a sector report and flags a "dry stripe" that's actually just how the package is supposed to look.

LEPA and LESA, the short version

LEPA (Low Energy Precision Application) drops the nozzle down near the furrow, often running in bubble mode so water lands as a small, concentrated pattern instead of a spray. Paired with furrow dikes, it's built to put water exactly where the furrow holds it and skip the canopy and the air in between. LESA (Low Elevation Spray Application) mounts the nozzle lower than a traditional spray head, usually 12 to 24 inches above the ground or crop, and still throws a spray pattern, just a shorter, lower-trajectory one than what you'd get off a high-pressure impact head.

Both exist for the same reason: cut evaporation and wind drift compared to overhead application. But they don't leave the same footprint, and that's the part that matters once you're comparing imagery to an expected pattern instead of eyeballing the circuit.

Why the wetted pattern isn't uniform anymore

A full-circle spray package puts down a reasonably even sheet across the wetted radius. LEPA in bubble mode puts water in the furrow and skips the ridge, so from directly overhead you get alternating wet and dry stripes that follow the row direction instead of a solid wetted sector. If you're used to reading a thermal pass against a flat "water should be here" assumption, that striping looks exactly like a nozzle problem, but it's the package doing its job as designed.

LESA sits in between. The pattern is more continuous than LEPA's furrow-and-dike setup, but drop height still changes how much water the canopy intercepts versus how much reaches the soil, which shows up differently in an index pass than a spray head mounted higher up would.

This is the actual reason package type belongs in the baseline geometry for a sector check, not just the nozzle chart in the pivot's as-built. A dry-sector flag has to know what "normal" looks like for that span's drop package before it can tell you what's abnormal.

Drop nozzle height and bubble mode on a mixed circuit

Most districts don't run one package circuit-wide. It's common to have a pivot with LEPA on the inner spans and LESA or a standard spray on the outer spans and end gun, because the outer spans cover more acres per pass and the economics of furrow dikes don't pencil out the same way out there. That means a single pivot can have two or three different expected wetting patterns stacked radially, and a sector report that doesn't carry drop nozzle height and package type per span is going to misread the transition zone between them every time.

It also means a tech who's new to that circuit, or covering for someone on vacation, can't just glance at a thermal image and know whether a stripe pattern is bubble mode working as designed or a dropped nozzle on a LESA span further out. Without the package baked into what the sector is supposed to look like, that's still a truck trip to find out by eye.

What this means for a sector check

A weekly comparison against pivot geometry only catches real dry spots and over-irrigation if it knows which drop package each sector is running and what that package's pattern is supposed to look like, not just where the wetted radius falls. Irrigation Monitor builds that package-aware baseline into the per-pivot report, so a furrow stripe from bubble mode doesn't get flagged next to an actual failed nozzle three spans over.

If your circuit mixes drop packages span to span, it's worth checking whether your current sector reporting even knows that.