Cleaning Up The Bush River
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An oily looking, foul smelling blue-green mass coated beaches and large portions of the Bush River this summer. On July 23rd, the Maryland Department of Natural Resources confirmed that the cause of this phenomena was Microcystis aeruginosa, a cyanobacteria when wind-rowed along the shore looks more like a blue-green paint spill than living organisms.
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Once considered a blue-green alga, Microcystis aeruginosa, is now known to be a bacteria that can cause health problems such as allergic reactions and intestinal irritation in people and can kill pets or livestock if large amounts are swallowed. Excessive growth of both Microcystis and green algae are caused by excessive nutrients entering the water, but the problems they cause are different.
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photo: Glenn R. Dudderar
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Green algae are microscopic plants that are an essential and healthy part of the Bush River and the Bay, but become a problem for aquatic life when excessive nutrients, especially nitrogen and phosphorus, over-fertilize the water. When this happens green algae become so abundant that they block sunlight needed by submerged vegetation. They also consume oxygen during the night that is needed by fish and other aquatic organisms or when the algae die and decompose. This process is called eutrophication, but green algae do not pose the health hazard Microcystis does.
Excessive green algal growth in the Bush River and the Bay is a problem that we have been trying to solve for over 30 years. The abundance of Microcystis in the Bush and other rivers of Maryland, however, is a warning that we have to do a better job of reducing nutrients entering our waters. Microcystis becomes excessive only when the water is highly over- enriched with nutrients. In the northern Bush River the nutrient causing most of the problem is phosphorus.
Phosphorus is a fertilizer and is represented by the middle number of the 3 numbers on a container of fertilizer, such as 20-10-5. In this example the fertilizer is 20% nitrogen (N), 10% phosphorus (P), and 5% potassium (K). Although nitrogen is a problem in the saltier waters of the Bay, it rarely causes problems in fresh water like the northern Bush due to differences in salt and fresh water chemistry. Because nitrogen enters the water from both the air and the land, it is normally abundant and thus rarely the cause of over-enrichment in fresh water. The nutrient that is naturally scarce in fresh water is phosphorous, and when it becomes abundant, eutrophication occurs. Highly eutrophic freshwater produces Microcystis.
Phosphorus becomes excessive in our waters when it is washed from the land or dumped into the water in the form of livestock waste or inadequately treated sewage. The water in the Bush was once clear because luxuriant vegetation on the land and wetlands absorbed and stored most of the phosphorus and prevented soil from washing into the river, even during years of heavy precipitation. Waste from livestock and humans was not a problem and what little phosphorus entered the water was quickly taken up by submerged aquatic vegetation and green algae. The remaining algae were consumed by clams, oysters and fish such as alewives and menhaden.
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Today, however, our activities on the land release abnormally large amounts of phosphorus into the water, and the organisms other than algae that once removed it are far fewer in number. The dissolved phosphorus becomes concentrated enough to promote large algal blooms and especially high concentrations produce masses of Microcystis. Even higher concentrations of nutrients can produce even more objectionable organisms such as Pfiesteria in saltier waters.
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photo: Glenn R. Dudderar
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To keep Bush River clean and clear, the citizens and government of Harford County need to keep phosphorus on the land where it is helpful and out of the river where it is harmful. In doing so we will also prevent nitrogen from running off of the land. Although that will not be of great benefit to the upper Bush, it will benefit the Bay where excess nitrogen is the major cause of excessive algal growth.
Fortunately, however, the citizens of Harford County can solve most of these problems, sometimes by methods that save time and money. Here's how.
Homeowners can reduce the amount of fertilizer they apply to their lawns by using lime to adjust the soil pH to 6.5-7.0 and by applying the right amount and kind of fertilizer at the right time. The Maryland Cooperative Extension Service and commercial nurseries have excellent information and services on how to do this. Fertilizer applicators such as drop spreaders apply fertilizer only to the lawn if used properly and not to adjacent walkways, driveways and roads as do spreaders that scatter fertilizer. Rain gardens and luxuriant border vegetation also help by reducing nutrients in run-off. Homeowners with septic systems should keep them in good working order and pump out the septic tank at least every other year.
Farmers can help by using soil and water conservation techniques such as conservation tillage, sod waterways, buffer strips, good manure management and the fencing of livestock from streams. Organizations such as the US Natural Resource Conservation Service, the County Soil Conservation District and Harford County offer financial incentives, technical assistance and/or services for a wide variety of soil and water conservation practices.
The citizens of Harford County must insist that county government do a better job of protecting wetlands and the lands adjoining our watercourses from development or at least high density development. The effects of any development must be minimized by the best erosion and storm water run-off control possible. We must also insist that our county do a better job of managing roadside drainage ditches so that they are not sources of erosion and sedimentation. Past mistakes must be corrected to reduce the effect of run-off from older developments, parking areas and roadways. Citizens can also support organizations such as Harford Land Trust that help landowners wanting to protect their land from further development.
Obviously none of the above can be accomplished without effort, even those that will immediately save us time and money. We have to be willing to learn, to stop repeating old mistakes, and to become better neighbors and informed active citizens. Some of the new ways will cost more in the short run, but failure to correct old mistakes as we can will ultimately cost more in expenses, lost profits and opportunities and less healthy, enjoyable living conditions.
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Photo: HLT