Ambient Stream Monitoring
Since October 1999, the Iowa Department of Natural Resources has maintained a network of stations to monitor ambient water quality in the state. Currently, a total of stream sites are sampled. However, the total number of stations monitored each year has varied. The most stations sampled were a total of 84 stream sites and 1 spring from 2003 to 2006.
Sites in this statewide ambient stream network have been sampled on a monthly basis since October 1999 for a variety of parameters. These data are used for a number of purposes, such as determining status and trends, to determine if Iowa’s rivers support beneficial uses for which they are designated, to calculate nutrient loads, and to support development of new or revised water quality standards.
Program Details
| Sampling Results (2016 to 2025) | 147,886 |
| # of Sites |
Current Ambient Stream Sites
Stream Water Quality Summary 2016 to 2025
| Analyte | Units | # Results | Min | 10th Percentile | 25th Percentile | Median | 75th Percentile | 90th Percentile | Max | Max Sample Date | % Non-detection |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Alkalinity, total | mg/l CaCO3 | 4,014 | 62 | 150 | 180 | 220 | 260 | 300 | 420 | 3/2/2020 | 0.00 |
| Ammonia-nitrogen | mg/l | 7,199 | Not calculated when non-detections exceed 50% | 6.6 | 12/11/2023 | 79.32 | |||||
| Calcium | mg/l | 3,959 | 15 | 52 | 63 | 75 | 88 | 100 | 150 | 2/9/2021 | 0.00 |
| Carbonaceous biochemical oxygen demand, standard conditions | mg/l | 7,182 | Not calculated when non-detections exceed 50% | 37 | 3/7/2016 | 80.69 | |||||
| Chloride | mg/l | 7,199 | 4.2 | 12 | 16 | 21 | 27 | 37 | 200 | 1/8/2024 | 0.00 |
| Chlorophyll a, free of pheophytin | ug/l | 7,198 | <1 | 2 | 4 | 9 | 23 | 62 | 570 | 11/8/2023 | 2.76 |
| Dissolved oxygen (DO) | mg/l | 7,188 | 3 | 7.8 | 8.7 | 10.6 | 12.4 | 13.5 | 20.1 | 8/11/2021 | 0.00 |
| Hardness, carbonate | mg/l | 7,199 | 10 | 200 | 240 | 290 | 340 | 390 | 600 | 1/12/2022 | 0.00 |
| Kjeldahl nitrogen | mg/l | 7,199 | <0.1 | 0.31 | 0.5 | 0.67 | 1 | 1.6 | 11 | 6/6/2019 | 8.49 |
| Magnesium | mg/l | 3,959 | 4.9 | 15 | 20 | 25 | 31 | 36 | 56 | 1/5/2022 | 0.00 |
| Nitrate + Nitrite | mg/l | 7,198 | <0.1 | 0.42 | 2.2 | 5 | 7.4 | 9.9 | 25 | 1/7/2025 | 6.47 |
| Organic Carbon | mg/l | 5,768 | <0.5 | 1.6 | 2.1 | 2.9 | 3.9 | 5.2 | 25 | 3/6/2018 | 0.19 |
| Orthophosphate | mg/l | 7,192 | <0.02 | <0.02 | 0.04 | 0.07 | 0.13 | 0.23 | 4.5 | 1/11/2023 | 12.81 |
| pH | None | 7,134 | 6.2 | 7.7 | 8 | 8.2 | 8.3 | 8.5 | 9.7 | 8/11/2021 | 0.00 |
| Potassium | mg/l | 3,959 | <1 | 1.7 | 2.2 | 3 | 4.4 | 6.2 | 23 | 3/6/2018 | 0.56 |
| Sodium | mg/l | 3,959 | 1.8 | 6.4 | 8.1 | 10 | 15 | 23 | 240 | 10/6/2021 | 0.00 |
| Sulfate | mg/l | 7,198 | <3.1 | 16 | 20 | 28 | 46 | 80.3 | 550 | 10/5/2023 | 0.13 |
| Temperature, water | deg C | 7,198 | 0 | 0.4 | 2.8 | 12.1 | 20.7 | 24.3 | 32.3 | 7/5/2022 | 0.00 |
| Total Dissolved Solids | mg/l | 7,197 | 70 | 270 | 310 | 360 | 430 | 500 | 2580 | 5/3/2021 | 0.00 |
| Total Phosphorus, mixed forms | mg/l | 7,199 | <0.02 | 0.06 | 0.11 | 0.19 | 0.32 | 0.53 | 4.4 | 1/11/2023 | 0.51 |
| Total Suspended Solids | mg/l | 7,200 | <1 | 4 | 10 | 33 | 86 | 220 | 3870 | 4/3/2017 | 0.29 |
| Turbidity | NTU | 7,188 | <0.1 | 2.8 | 6 | 16 | 40 | 98.3 | 2600 | 9/4/2018 | 0.72 |
| Volatile Suspended Solids | mg/l | 7,200 | <1 | 2 | 3 | 7 | 16 | 34 | 420 | 7/2/2019 | 0.51 |
Project Codes in this Program
| Code | Description |
|---|
Inactive Ambient Monitoring Sites
Sites may no longer be monitored due to a variety of reasons. They may be temporarily or permanently moved to a new site, or abandoned completely. Reasons for inactivity include construction on nearby roads/bridges, traffic safety concerns, or changes to stream morphology and/or accessibility.
| SiteID | Site | County |
|---|