Call a Plumber!!! I Think Our Watershed is Broken.

A general definition of a watershed is the region of land within which every drop of rain and surface water flows into a common drainage. Think of it as a big basin.  The Chesapeake Bay Watershed is a large and well-studied area that covers 64,000 km² and includes parts of Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia.  It is also home to about 17 million people and 185 million livestock animals.  In addition to the typical pollutants we tend to associate with populated areas—industrial chemicals, heavy metals, vehicle exhaust, road salt—we generate a lot of nitrogen (N) and phosphorus (P) that eventually makes its way to the Bay.  But wait, those are good, important nutrients, right?  Nitrogen and phosphorus are natural parts of aquatic ecosystems. Nitrogen is also the most abundant element in the air we breathe. Nitrogen and phosphorus support the growth of algae and aquatic plants, which provide food and habitat for fish, shellfish and smaller organisms in water.  However, too much nitrogen and phosphorus in the water cause algae to grow faster than ecosystems can handle. Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that aquatic life needs to survive. 

Large growths of algae, called algal blooms, can severely reduce or eliminate oxygen in the water, leading to illnesses or even death in fish populations. Some algal blooms are also harmful to people because they produce elevated toxins and bacterial growth that can cause water contamination. 

So what are we doing about this in the Chesapeake Bay Watershed?  A LOT!  Policies are in place to reduce nutrient loads entering our rivers from farms and cities.  Education efforts from elementary schools to town hall meetings teach people about the problems and some of the solutions.  Throughout the region, parts of many streams have been “restored” to stabilize their banks to reduce erosion, add engineered structures to slow down the water, or reconnect streams with their floodplains through the creation of wetlands.  The goal is to reduce the volume of N and P being transported, and allow more time for nutrients to be transformed to inert states before they reach the Bay.   But a number of the questions remain regarding how well some of these restoration practices work:

·         Are they successfully changing the chemistry of the water?

·         How much improvement in N and P removal can we expect ?

·         What are the best practices?

·         Where are they most effective?

We begin to answer these questions through long-term monitoring and frequent sampling of the water upstream and downstream of where a restoration strategy has been put it in place.  We measure the water chemistry to look for seasonal differences, changes between normal flow conditions and during storm events, and any entry of nutrients from sources we can’t see.  Until now you might have thought that a watershed was two-dimensional (2-D), only at the surface.  We have to learn to think in FOUR dimensions; in addition to the area above ground, there is a complicated, dynamic system underground (3-D), and things change through time (4-D).  This is especially true when we think about urban areas.  All of those leaky pipes and sewer systems are part of the problem!

Credit:  Rich Puoyat

Rapid land development that brought rise to large cities and agricultural areas has altered our watershed permanently.  We have a long way to go to identify how much damage has been done and how we can make improvements.  People aren’t moving away from our nation’s waterways anytime soon, so we have to learn how to coexist and create sustainable cities.  For now, save your call to the plumber (but put a scientist on speed dial!) and surf your watershed to find out what’s going on in your own area, and how you might help work toward solutions.