Map Trap Snap

What it is

Map Trap Snap (MTS) is a community-science map of rodenticide bait boxes in the Massachusetts part of the Connecticut River watershed. You photograph a bait box; the app places it on the map and traces the path rain falling there would likely take, downhill and downstream, to the Connecticut River.

It is a student research project by Deanna Saccoach, Natural Resources program, Holyoke Community College, and part of her SGAR Pathways project on where anticoagulant rodenticides could reach waterways.

Created by Deanna Saccoach · ORCID 0009-0009-5836-3561 · © 2026 Deanna Saccoach

What the flow path shows, and what it doesn't

• The path is a likely route over the land surface, not a measured one. Storm drains and sewer pipes are not mapped, so water may go underground first.
• It does not show that any poison has moved.
• No one needs to open or touch a box. Massachusetts requires a label naming the pest control company and its phone number, the date, the product's name and EPA registration number, and its active ingredients, but only on bait stations used indoors (333 CMR 13.08). Outdoor boxes have no state label rule, and companies often put the label inside the box, so a photo shows the label only when it is on the outside. Federal product labels, which are legally binding, require outdoor above-ground bait to be in tamper-resistant bait stations.
• A combined sewer overflow (CSO) outfall is listed only when it discharges into a stream reach the traced water actually flows through, not because it is nearby.
• Why outfalls are noted: in Germany, heavy rain during sewer baiting sent anticoagulant rodenticides through treatment plants and combined sewer overflows into streams, where they built up in fish livers (Regnery et al. 2020). Poisoned rodents that die in the sewer can also be flushed out through overflows, and the poison lasts in a rodent's liver long after death: in rats, brodifacoum's half-life in the liver is about 114 days, so a carcass can carry it into the river (Regnery et al. 2019). That makes CSO outfalls places at potential risk of rodenticide exposure. Tracing each bait box's flow path shows which outfalls, and which stretches of river below them, could also receive rodenticide washed off the land surface. Whether sewers in the Connecticut River watershed are baited is not yet known: Massachusetts cities and towns can't override state pesticide rules, but each can limit or prohibit anticoagulant rodenticides on property it owns (ERG 2025), so sewer baiting can differ from one municipality to the next.

How it works

1. Photo check. An AI vision model (Google Gemini, through Netlify AI Gateway) checks that the photo shows a bait box. If it doesn't recognize one, you can still log it; it waits for the project host to approve it.
2. Location. A photo taken in the app uses the phone's GPS. A photo from the camera roll can only be placed where its own location tag says it was taken (within 25 m). The pin can be moved up to 30 m, about across a street.
3. Flow trace. From the point, the app finds the nearest mapped stream and follows it downstream with the U.S. Geological Survey's Network-Linked Data Index (NLDI) and NHDPlus, down the Connecticut River to where it crosses into Connecticut (42.0177° N).
4. Outfalls. EPA's 2022 CSO outfall locations within 250 m of the traced stream are checked; an outfall is linked only if it sits on a reach this water flows through, its receiving water matches, and it is at or below where the water enters.

How to cite

Saccoach D. 2026. Map Trap Snap [software]. Holyoke (MA): Holyoke Community College. https://maptrapsnap.org

Sources and credits