This is the second of a series of annual reports that present the most current figures about the status of nutrient and sediment reduction efforts toward meeting the Bay Program’s water quality goals.
This pullout shows how various river basins, states—and various nutrient and sediment sources—are progressing toward meeting nutrient and sediment reduction goals that have been set for 2010.
Most of the information in this report comes from computer modeling conducted by the Chesapeake Bay Program. The 2003 model estimates, the most recent available, were released in February.
The model is used like an accounting program to keep track of nutrient control practices being implemented by the states, and their predicted impact on the Bay under long-term average rainfall conditions. (High rainfall years cause more nutrient runoff.)
Why use a model? Discharges from wastewater treatment plants and other “point sources” are monitored, but it is much harder to measure the effectiveness of thousands of individual runoff control practices—forest buffers, cover crops, nutrient management, stormwater and so forth—distributed across the landscape, especially when each is affected by local weather conditions.
Jurisdictions need annual assessments from computer models to help understand where they are—and how far they have to go—without the influence of hydrology. At the same time, actual water quality monitoring shows what is happening in the real world.
The 2003 figures show that nitrogen and phosphorus levels were each reduced by less than 1 percent from 2002.
Part of that is a bit of an apples and oranges comparison. The computer model estimates nutrient reductions from runoff (nonpoint sources) based on “average” rainfall conditions.
But the model also incorporates real monitoring data from wastewater treatment plants and other dischargers (point sources). Because 2003 was a wetter than normal year, many plants handled greater flows—because of stormwater runoff and infiltration into old pipes—and therefore operated less efficiently. As a result, watershedwide point source discharges increased slightly in 2003 over 2002 levels.
The bottom line: The model reflects normal rainfall conditions for nonpoint sources, but not for point sources. Hence the apples and oranges.
But that doesn’t change by much the take home point. In 2002, the model estimated that about 277.7 million pounds of nitrogen reached the Bay from its watershed. In 2003, that dropped to 275.1 million pounds. This is less than a 1 percent drop.
The goal needed to restore a healthy Bay is 175 million pounds of nitrogen.
Even if the point source increase were factored out, the 2003 figures would not have substantially changed. The rate of progress would have remained far below what’s needed to meet the 2010 cleanup goal. As a result, the hill to be climbed is getting steeper each year.
Last year, when the Bay Journal reported the 2002 figures, the region needed to cut the amount of nitrogen reaching the Bay by 13 million pounds annually to reach its goal. A year later, the 2003 figures show that reductions of 14.3 million pounds a year (from 2004 through the end of 2010) are needed to meet the goal.