Ambient Lake Monitoring
The Ambient Lake Monitoring program samples lakes in Iowa over the summer recreational season. Each lake is sampled three times between May and September: once in early summer, once in mid-summer, and once in late summer/early fall. Data from this project are used to assess the health of our lakes and target individual lakes for restoration and watershed improvement activities. Monitoring is currently completed through a partnership with the Iowa State University Limnology Laboratory.
Program Details
| Sampling Results (2016 to 2025) | 72,954 |
| # of Sites |
Current Ambient Lake Sites
Lake Water Quality Summary 2016 to 2025
Summary statistics last calculated 3/31/2026 2:50:25 PM
| Analyte | Units | # Results | Min | 10th Percentile | 25th Percentile | Median | 75th Percentile | 90th Percentile | Max | Max Sample Date | % Non-detection |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Ammonia | mg/l | 3,966 | Not calculated when non-detections exceed 50% | 0.433 | 7/17/2017 | 50.40 | |||||
| Ammonia-nitrogen | mg/l | 4,019 | <0.0006 | <0.0048 | 0.01485 | 0.028 | 0.07 | 0.19 | 2.53 | 5/1/2024 | 13.86 |
| Calcium carbonate | mg/l | 3,992 | 37.3 | 81 | 95.6075 | 121 | 150 | 180.797 | 485 | 8/6/2018 | 0.00 |
| Depth, Secchi disk depth | m | 3,555 | 0 | 0.3 | 0.425 | 0.7 | 1.3 | 2.5 | 11.175 | 6/5/2023 | 0.00 |
| Dissolved oxygen (DO) | mg/l | 3,505 | 0.8 | 5.3 | 6.7 | 8.2 | 9.56722 | 11.2 | 26.1 | 5/16/2016 | 0.00 |
| Dissolved oxygen saturation | % | 3,505 | 9.1 | 62.54686 | 79.45 | 96.7 | 112.48 | 134.56 | 310.1 | 9/8/2016 | 0.00 |
| Escherichia coli | MPN/100ml | 413 | <1 | <1 | <1 | 10 | 10 | 20 | 6130 | 5/27/2020 | 47.94 |
| Fixed suspended solids | mg/l | 4,017 | <0 | <1.2 | <3.2 | 4 | 7 | 13 | 182 | 5/22/2023 | 42.15 |
| Kjeldahl nitrogen | mg/l | 3,876 | <0.2 | 0.62 | 0.8615 | 1.26 | 1.8 | 2.35 | 8.84 | 6/13/2023 | 5.83 |
| Microcystin | ug/l | 3,389 | Not calculated when non-detections exceed 50% | 126.9 | 10/23/2024 | 52.91 | |||||
| Nitrate + Nitrite | mg/l | 3,876 | <0 | <0.04 | <0.06 | 0.105 | 0.311 | 2.0099 | 21.8 | 5/29/2024 | 46.18 |
| Orthophosphate | mg/l | 4,018 | Not calculated when non-detections exceed 50% | 4 | 5/1/2025 | 65.21 | |||||
| pH | None | 3,493 | 6.45 | 7.782 | 8.05 | 8.3 | 8.58429 | 8.85 | 10.13 | 5/22/2023 | 0.00 |
| Phycocyanin | ug/l | 3,607 | <1.8 | 8.106 | 35 | 79.387 | 121.2 | 197.74 | 11107.53 | 6/28/2022 | 7.54 |
| Specific conductance | uS/cm | 3,533 | 79.4 | 220 | 265 | 337.6 | 430 | 542.86 | 1230 | 9/14/2020 | 0.00 |
| Temperature, water | deg C | 3,542 | 10.8 | 19.1 | 21.7 | 24 | 26.0375 | 27.5 | 31.7 | 7/11/2017 | 0.00 |
| Total Dissolved Solids | mg/l | 3,528 | 51.7 | 141.74 | 172 | 219.7 | 280 | 352.65 | 800 | 9/14/2020 | 0.00 |
| Total Phosphorus, mixed forms | mg/l | 4,019 | <0.003 | 0.024 | 0.042 | 0.0729 | 0.1267 | 0.212 | 1.992 | 9/15/2021 | 3.06 |
| Total Suspended Solids | mg/l | 4,017 | <0.8 | <3 | 5.5 | 10 | 18 | 28 | 413 | 5/31/2022 | 11.30 |
| Turbidity | NTU | 3,359 | <0 | 0.9 | 3.4 | 8.2 | 15.715 | 29.042 | 427 | 8/23/2017 | 6.07 |
| Volatile Suspended Solids | mg/l | 1,725 | <1.1 | <3 | <4.3 | 5 | 10 | 16 | 357.5 | 5/31/2022 | 34.43 |
Project Codes in this Program
| Code | Description |
|---|
Additional Summary Calculations
| Parameter | Value |
|---|---|
| TSI (Secchi) | 59 |
| TSI (TP) | 71 |