Iowa DNR
AQuIA
Water Quality Monitoring
Surface Waters - Groundwater
Physical - Chemical - Fish Tissue

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 (2000 to 2021) 155,166
# of Sites

Current Ambient Lake Sites

SiteID Site County

Lake Water Quality Summary 2000 to 2021

Summary statistics last calculated 1/18/2022 7:13:47 AM
Analyte Units # Results Min 10th Percentile 25th Percentile Median 75th Percentile 90th Percentile Max Max Sample Date % Non-detection
Ammonia mg/l 6,972 <0 <0 <0.00093952615 0.01 0.014 0.017 0.433 7/17/2017 49.30
Ammonia-nitrogen mg/l 8,175 <0 <0.00742 <0.016 0.05 0.13 0.2117 1.734 8/11/2004 46.72
Calcium carbonate mg/l 3,853 9 81 96.69 124 157 192 485 8/6/2018 0.00
Chlorophyll a ug/l 7,944 <0 3.5 8 22.8 46.655 88 743 8/3/2005 6.65
Depth, Secchi disk depth m 8,747 0.05 0.3 0.5 0.8 1.4 2.6 10 7/21/2015 0.00
Dissolved oxygen (DO) mg/l 8,533 0.3 5.9 7.3 8.8 10.5 12.7 30.2 5/23/2011 0.00
Dissolved oxygen saturation % 6,505 4 70 87 105 126.9 155.96 322 8/3/2005 0.00
Escherichia coli MPN/100ml 792 <1 <1 <1 3 10 20 6130 5/27/2020 46.46
Fixed suspended solids mg/l 9,594 <0 <1 2.2 4 8.4 17 378 5/31/2011 24.70
Inorganic nitrogen (nitrate and nitrite) mg/l 9,743 <0 <0.04 <0.06 0.16 0.7 3.9 24.53 5/14/2013 49.30
Kjeldahl nitrogen mg/l 6,348 <0.1 0.52 0.82 1.17 1.7 2.35 12.92 8/8/2011 7.21
Microcystin ug/l 1,708 Not calculated when non-detections exceed 50% 64.81
Orthophosphate mg/l 8,787 Not calculated when non-detections exceed 50% 63.50
pH None 8,608 6.5 7.9 8.2 8.4 8.7 9.1 10.8 7/14/2005 0.00
Phosphate-phosphorus mg/l 9,351 <0 0.0273 0.0447 0.076 0.13 0.2178 2.8 7/25/2007 2.06
Phycocyanin ug/l 1,882 <1.8 <4.369 13 38 75.375 142.9 4733.81 6/11/2019 14.45
Specific conductance uS/cm 8,634 0.202 221 273 361 463 571 1361 7/11/2000 0.00
Temperature, water deg C 8,655 7 17.7 21.2 24.1 26.3 27.8 33.8 7/9/2002 0.00
Total dissolved solids mg/l 4,865 0.3 140 175 220 300 350 754 9/9/2019 0.00
Total suspended solids mg/l 9,736 <0 4 6 11.2 20 34 452 5/31/2011 5.71
Turbidity NTU 8,436 <0 3 6.755 14.2 29 57 2333 8/7/2000 0.49
Volatile Suspended Solids mg/l 7,298 <0 <2 4 8 11 19.3 196 7/25/2006 14.14
Project Codes in this Program

Code Description

Additional Summary Calculations

Parameter Value
TSI (ChlA) 66
TSI (Secchi) 58
TSI (TP) 72