a waterflea
Invasive SpeciesFound in 7 lakes
a waterflea appears on state infested-waters lists for 7 surface waters. Boaters and anglers moving gear in or out of those lakes carry a clean-drain-dry obligation under state law. 7 lakes — narrow enough that aggressive containment is still on the table. Most upper-Midwest invasives that established here did so quietly over a decade before anyone noticed, so a low number today is not a guarantee for tomorrow.
The presence of a waterflea does not directly change a lake's LakeGrade rubric score — the grade measures the water itself, not the species inhabiting it. But invasive presence is a meaningful adjacent signal worth reading alongside the grade.
Lakes with a waterflea
| Lake | County | State | Grade | Depth |
|---|---|---|---|---|
| Stockton Lake by Dam | Cedar | MO | A | - |
| Lake Nehai Tonkayea | Chariton | MO | A | - |
| Mark Twain Lake by Hwy J | Ralls | MO | C | - |
| Mark Twain Lake | Ralls | MO | D | - |
| Dutchman Lake | Johnson | IL | F | - |
| Montrose Lake | Henry | MO | F | - |
| Harrisonville Lake | Cass | MO | NR | - |
Frequently Asked Questions
How many lakes have a waterflea?
a waterflea has been documented in 7 graded lakes: 6 in Missouri, 1 in Illinois.
Does a waterflea affect water quality?
Invasive species can significantly affect lake ecosystems. They may alter nutrient cycling, displace native species, and change water clarity. Lakes with a waterflea should be monitored for changes in water quality over time.
Invasives Found With a waterflea
Source: EPA National Aquatic Resource Surveys, 2026.