Most summers, my family rents a house near Little Sebago Lake in Maine for a week. It’s a fantastic escape from the daily grind – we kayak, we swim, we go tubing, we fish, and I get out and go birding. (This area is home to lots of cool birds, including the common loon. IMHO, it is absolutely impossible to get bored no matter how long you stare at such a bird, and no matter how little it does during that time.)
But most of all, we decompress. Lakes are good for that – they’re often calm and quiet, and they let you be the same.
Unfortunately, there’s some disquieting news about the nation’s lakes. Today, EPA released its draft National Lakes Assessment, an attempt to document the physical, chemical, and biological state of our lake resources, by conducting in-depth sampling at roughly 900 lakes. While I will try to resist lake-based puns about EPA’s conclusions (“not every pond is golden,” “not every lake is great,” you get the idea), my read of the report leads me to conclude that the mental image I have when someone mentions the word “lake” – a clear, pristine water body – might often be wrong.
The agency and its partners (a host of state and tribal resource agencies) deserve our thanks for completing this survey. After all, knowing what our problems are will help us identify solutions. And the report does this well – a couple of important stressors to lakes emerge from the information presented, and fortunately there are ready solutions to these problems.
Too Much of a Good Thing – Nutrient Pollution
First, the data show a serious problem with nutrient pollution into lakes, with important implications for public health and for wildlife. Across the country, 42 percent of lakes are in “fair” or “poor” condition based on phosphorus concentrations, and 46 percent are “fair” or “poor” for nitrogen. Although it may sound like the diet you wish your kids would follow, too many nutrients are no good for aquatic ecosystems As EPA says, “[l]akes with excess nutrients are two-and-a-half-times more likely to have poor biological health.”
Nutrient pollution causes algal blooms which are ugly, can produce harmful toxins, and can rob the water body of oxygen when they die and decompose. So, it should be a bad sign that nearly half the lakes sampled have less than “good” nutrient conditions, and an even worse sign that certain regions have much more serious problems. For example, in the temperate plains region (including parts of IA, ND, SD, MN, MO, KS, NE, OH, IN, IL, and WI), 62 percent of the lakes were rated “fair” or “poor” for phosphorus, and 73 percent for nitrogen. In the northern plains (including parts of ND, SD, MT, WY, and NE), 78 and 91 percent of lakes were “fair” or “poor” for phosphorus and nitrogen, respectively. Not surprisingly, lakes in these areas also posed higher-than-national exposure risks for cyanobacteria, a particular kind of algae that can produce toxins; in the temperate plains, 52 percent of lakes posed a moderate or high exposure risk, while 59 percent of lakes in the northern plains had such risks.
Controlling nutrient pollution would reduce these risks to lakes and also clean up other aquatic ecosystems that are suffering the ill effects of nutrient-induced algal growth and oxygen depletion, such as the Chesapeake Bay and the Gulf of Mexico. There are lots of technologies in use by responsible wastewater treatment plants, stormwater managers, and farmers across the country that effectively reduce nutrient pollution, but those approaches are not being applied consistently enough to protect our waterways. Examples are biological nutrient removal by wastewater treatment plants, use of native plants and other landscaping that needs less fertilization by municipalities, and use of cover crops and stream buffers by farmers.
Maybe Clear-cutting the Lakefront Lot for that Cottage Isn’t the Best Idea – Shoreline Disturbance
Nutrients are actually only the second-worst problem for lakes, according to the EPA draft report. The thing that adversely affects the greatest percentage of lakes nationwide, it says, is degraded lakeshore habitat. When EPA looked at the amount and type of vegetation on the shoreline of the country’s lakes, it found that 54 percent of lakes had “fair” or “poor” lakeshore habitat condition. Relatedly, the agency reported that 65 percent of lakes were moderately or highly disturbed by human activity.
Disturbing natural vegetation and landscapes has well-known harmful effects. The EPA report, for instance, references a Wisconsin Department of Natural Resources estimate that “unbuffered developed sites contribute five times more runoff, seven times more phosphorus and 18 times more sediment to a lake than the naturally forested sites.”
Again, however, there are solutions at hand. The key strategy to dealing with the harms that development can cause to water resources is green infrastructure – the use of techniques like rain gardens, porous pavement, water reuse, green roofs, and more to mimic the natural hydrology of developed sites. EPA’s report even makes specific mention of this idea, saying that green infrastructure, or low impact development, “will contribute to groundwater recharge, improve water quality, reduce flooding, preserve habitat, and protect lake quality.”
Today’s report shows that the health of our lakes depends on taking smart action when we use the land around them and when we allow pollution to be discharged into them. It also shows that we’re not yet doing a good enough job.