1	Lake Monitoring
2	Introduction to Lakes The Iowa DNR has cataloged 5,432 “standing waters” in Iowa Lakes and ponds 115 Significant publicly owned lakes 67 “meandered” lakes Reservoirs and Impoundments 4 Flood control reservoirs Wetlands Total acres: 161,366
3	Uses of Lakes Recreation Ecological Resources Drinking water Agricultural water supply Industrial water supply “Traps” for sediment and nutrients
4	Impaired Lakes
5	Impaired Reservoirs
6	Impaired Wetlands
7	Percent of water bodies impaired Lakes 36% Impaired (partially supporting or not supporting designated uses) 41% Fully supporting but threatened Wetlands 57% Impaired 37% Fully supporting but threatened
8	“Traps” or “Sinks” Standing waters are direct reflections of the watersheds that surround them Lentic waters (standing waters) serve as sinks or storage areas The natural function of lentic waters is to collect, clean, and release water Pollutants can become concentrated
9	Formation of lakes and ponds Naturally formed lakes Glacial lakes (kettle lakes)
10	Reservoirs and Impoundments
11	Wetlands Term used to describe all other lentic waters Fens – Spring-fed wetlands, accumulation of peat Bogs – Precipitation-fed wetlands, stagnant water Swamps – Forested wetlands Marshes – Wet prairie wetlands Formed by glacial processes like lakes
12	Lake Ecology Lake Turnover – surface water sinks and forces water at the bottom to rise, mixing nutrients and oxygen throughout the water column Stratification – formation of layers/zones due to difference in temperature Many of Iowa’s lakes are too shallow to stratify Light availability determines the distribution of aquatic communities
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17	Site selection Most representative location Deepest point In circular natural lakes – the center In man-made reservoirs – near the dam If I don’t have a boat what do I do? Sample from a dock Sample from the shore Indicate dock/shore sampling on the datasheet
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19	Sampling from a dock
20	Point sampling and sampling frequency Sampling from a specific depth Elbow depth (Approx. ½ meter) Bi-monthly sampling is recommended From ice-out to freeze-over, between 10 AM and 3 PM Be consistent – If you can only sample monthly or quarterly then stick with it! Remember – SAMPLE SAFELY!!
21	Habitat Assessment Describe Lake Banks Include distances and landmarks in your description Adjacent Land Use Include distances and landmarks in your description
22	Habitat Assessment continued Weather Same as stream monitoring Air Temperature Precipitation Obtain from local radio, TV, newspaper or rain gauge (if one is located in the watershed) Wind direction and speed
23	Physical Assessment Site Location Open Water or Shore/Dock Secchi Disc Depth Water temperature Water Level Above Normal, Normal, Below Normal If you can, measure the amount above or below normal please do so on the datasheet Water Odor
24	Chemical Assessment - pH Average pH in Iowa lakes is 8.0 High pH levels can cause problems By increasing the ability of the water to dissolve metals Lakes with high pH often contain little or no algae (a food chain base)
25	Chemical Assessment – Nitrite + Nitrate Problems caused by forms of nitrogen are hard to detect in lakes Sources include commercial fertilizers, failing septic systems, or animal waste Increases plant and algae growth
26	Chemical Assessment - Phosphate Limiting factor for algal growth in most Iowa lakes However, if phosphate levels are high enough Nitrogen will become the limiting factor Largest cause of nutrient enrichment in lakes Can come from runoff from agriculture, failing septic systems, detergents, and animal inputs Orthophosphate – usually found in low concentrations because it is quickly taken up by plants
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28	Chemical Assessment – Dissolved Oxygen The amount of oxygen in the lake is an indication of what types of wildlife can live there Hypoxic conditions affect lakes just like they do streams
29	Biological Assessment Water Color Chart Experimental chart that may indicate which communities of plankton (algae, diatoms, phytoplankton) are present You may also record a “plant list” or any exotic species found in the Other Observations text box May do a benthic macroinvertebrate sampling using the stream field form if you wish
30	Biological Monitoring A more accurate way to assess the biological life of a lake or wetland would be to look at the frog and toad populations If you are interested in this please see information on the NatureMapping program on page 16-6 of your manual They are joining forces with the DNR Frog and Toad survey to monitor populations of these critters
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