Cottage Grove, MN
Lead detected, under the action levels
Latest 90th-percentile lead: 3 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Who runs the water here
Cottage Grove serves about 42,760 people through 13,853 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Washington County, Minnesota. EPA system ID: MN1820004; phone on file: 6514582842. They can tell you what your service line is made of and whether they pay to replace it.
Cottage Grove's lead record
Against the period ending 2025 (2 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Cottage Grove is 6 ppb across 5 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 3 ppb |
| 2025 | 2 ppb |
| 2022 | 2 ppb |
| 2019 | 3 ppb |
| 2016 | 6 ppb |
Against other Minnesota systems
Of the 966 Minnesota systems with a lead result, the median latest reading is 0 ppb; 7 are over 15 ppb right now and 48 have gone over at some point. Cottage Grove's 3 ppb sits at the 86th percentile in Minnesota and the 83rd nationally (higher means more lead).
Other water systems in Washington County
28 other systems share Washington County; 1 of them has a higher latest lead result than Cottage Grove. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Woodbury | 82,643 | 3 ppb |
| Oakdale | 30,144 | 2 ppb |
| Stillwater | 19,462 | 2 ppb |
| Hugo | 12,047 | 0 (not detected) |
| Forest Lake | 11,800 | 2 ppb |
| Lake Elmo | 10,978 | 0 (not detected) |
| Mahtomedi | 8,818 | 0 (not detected) |
| Saint Paul Park | 5,427 | 1 ppb |
| Oak Park Heights | 4,776 | 2 ppb |
| Newport | 4,000 | 2 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Cottage Grove, MN may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Cottage Grove whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. The action level is dropping - the 10 ppb rule from 2027.