A Tale of Two Streams

A textbook example of how land-use determines the quality of our waters. 

Below is a scientific comparison of two streams that begin in the town of Bryans Road.
One drains land that is somewhat urbanized. The other drains mostly forested
land.

The comparison finds that the more urbanized stream:

-is muddier.

-has higher levels of pollutants.

-has fewer species of fish.

-no longer supports migratory fish spawning.

-has fewer types of other water critters.

The story of these two streams explains:

  • why a Stormwater Utility Fee is a wise investment to protect our waters and the Chesapeake Bay. The fee pays for retrofitting past development with controls that moderate the stormwater flowing from lawns and rushing from roofs, roads, parking lots, and other hard surfaces during rainstorms. 
  • why a revised Comprehensive Plan--the blueprint for where development occurs--is needed in Charles County to protect its many waterways from poorly located and spread-out new development. Without smarter growth, we will be paying in the future for more damage to our beautiful streams, rivers, and estuaries.


Introduction to the two streams

During the Campaign to Save Chapman Forest from a mega-development, two sister streams flowing through what is now Mattawoman Wildlands were examined with unusual intensity by scientific agencies, a developer's consultant, and MWS. After the site was saved, volunteers continued monitoring through Maryland's StreamWaders program. The end result is a remarkably complete picture of the nature of the two streams.

The map below shows the two streams and the surrounding land that drains, or "sheds", water into the streams. The boundaries of these "watersheds" are shown with grey outlines.

The red-colored crosses mark sites that were continuously monitored for pollutants and sediments by the Smithsonian Environmental Research Center (SERC) for over two years in the late 1990's. The pie charts report land-use profiles upstream of each site (see key). Note the greater development in the northern stream.

The two streams are particularly important because they lie in a larger "Stronghold Watershed."  Stronghold watersheds are deemed "the most important areas for the protection of Maryland’s aquatic biodiversity," that is, the sum total of the diversity of life residing in the water.



Comparing pollution in the two streams

The chart below summarizes the Smithsonian's measurements. These show that the relative amounts of nutrient pollution and sediment pollution increased several fold in the more urbanized stream.


*Sediment (or solids) refers to mud suspended in the water. Muddy water shades out the
growth of beneficial submerged plants, thus depriving our waters of life-giving habitat for everything from snails to fish. Sediment also clogs the gills of salamanders, fish, snails, mussels, and aquatic insect larvae, and suffocates their eggs.
  
**Nutrient pollution refers to nitrogen and phosphorus, the same ingredients in lawn and
garden fertilizers.  Lawn owners are familiar with the problem of too much fertilizer harming grass. Problems also occur when these nutrients wash into our waterways, where they fertilize algae. Almost all of our waters chronically have too much algae due to nutrient pollution.

Like mud, algae clouds water, stealing light from water plants and obscuring the vision of fish, turtles, and other aquatic hunters. And when algae dies, decomposition depletes the water of the oxygen that is needed by all aquatic organisms. This stresses aquatic life. In warmer months, the algae can "bloom" leading to fish kills and poisoning the water for people.


Biological response to land development: fewer fish species

The charts below tell that the number of fish species declines significantly when a watershed is developed.

In the early part of the 21st century, Mattawoman's river and estuary had a healthy total of 54 species of fish, in the top 6% of comparably sized Maryland watersheds.  This number may be declining, as the number of species in the estuary began to drop dramatically around 2005 from over-development of the watershed. A smarter-growth land-use plan, and protection of the stream valley, is needed to stem the fall and to set the stage to reverse the trend.



Biological response to land development:  migratory fish are shut out


The streams and rivers feeding the Chesapeake Bay and its tributaries once teamed with mighty spawning runs of River Herring, American Shad, and Hickory Shad. These fish live in the Atlantic ocean, but spawn each spring in freshwater before returning to the sea.  Other fish, like Yellow Perch, migrate less far, but still earn the term anadromous, from Greek roots meaning upward running

Mattawoman Creek has been heralded by fisheries scientists as the most productive nursery in the Bay in large part for its anadromous Alewife and Blueback Herring (collectively, River Herring) and White Perch.

But this stature is in jeopardy: as the Tale of Two Streams tells, spawning by River Herring, as detected by their eggs captured in a net, is completely absent in the more urbanized stream. 



Research by the Maryland Department of Natural Resources, using data supplied by MWS, indicates that one reason urbanization pushes out migratory fish is road salt, which could confuse fish parents swimming toward fresh water.


Biological response to land development:  bottom critters decline

Biologists have discovered that the mix of stream dwellers indicates the quality of a stream, because critters vary in their tolerance to pollution.

Important critters for this purpose are the bottom dwellers, such as aquatic worms, crayfish, pill clams, and especially insect larvae. These organisms, called benthic macro-invertebrates (defined in the figure below) are also important in their own right for their role in the food web.  Nearly all feed larger creatures from fish to birds to racoons. But some also shred organic matter like leaves so that even tinier, microscopic creatures can feed, that will in turn feed tadpoles and fish and salamander larvae.

By examining the mix of bottom-dwelling species, biologists arrive at an index of biotic integrity for the stream, which can be summarized as good, fair, or poor. Volunteer collection of these bottom dwellers by MWS for
Maryland's StreamWaders program consistently shows the forested stream
to exhibit a markedly higher quality than the more urbanized stream.





Summary

  • Of the two Mattawoman tributaries draining Bryans Road, the more urbanized stream exhibited several-fold increases in:

-sediment

-excess nutrients 

  • The "index of biotic integrity" for bottom-dwelling
    invertebrates declined in the more urbanized stream. The site nearest the center of urbanization rated “poor.” The same stream, after flowing through forest, rated fair. The south tributary, with a primarily forested watershed, rated good at all sites.
  • There are fewer fish species (by 35%) in the more urbanized stream.

  • Migratory River Herring were completely absent in the more urbanized stream.

Is there a solution to land-development degrading our waters?

Two decades of effort to clean up the Chesapeake Bay have made significant progress by focusing attention on the "low hanging fruit," like improved sewage treatment plants.

However, we continually fall short of the ultimate goals, and pollution from development is actually increasing!  A large part of the problem is sprawl development, which is contributing to the loss in the Bay watershed of 100 acres of forest per day.  Said another way, the amount of hard surfaces that are impervious to rainwater is increasing five times faster than population. 

Mattawoman Creek is the perfect example of the problem. It is sprawl development that caused Mattawoman to begin declining in the 1st decade of the 21st century. While technological fixes help, they are no substitute for sound land-use practices that follow smart-growth principles: protect forest, avoid sensitive areas, protect stream valleys and employ wide buffers around wetlands and streams, and offer housing opportunities in walkable communities serviced by mass transit to help accommodate population growth.



References used in this report

[1]  T.E. Jordan, D.L. Correll, D.E. Weller, “Mattawoman Creek Watershed: Nutrient and Sediment Dynamics”, Smithsonian Environmental Research Center (2000).

[2] Searchable StreamWaders data

[3] J.P. Long, “Icthoyplankton Sampling of Anadromous Fish Usage in Mattawoman Creek,” reports filed with Maryland Department of Natural Resources (2000).

[4]  J. O’Dell, J. Gabor, R. Dintaman, “Survey of Anadromous Fish Spawning Areas-Completion Report,” Maryland Department.

[5]  E.A. Engineering, Science, and Technology, Inc., “Anadromous Fish Survey of Two Un-named Tributaries to Mattawoman Creek,” (1995).