Mattawoman Creek: A Threatened Treasure by Bonnie Bick Migratory fish have, in general, experienced precipitous declines along the Atlantic seaboard in the twentieth century. The million-pound harvests of yellow perch seen at the turn of century dipped to 15,000 pounds in 1982, a feeble 1 to 2% of historical levels, and now fluctuate around 50,000 pounds, in part through increased fishing effort. On their way to spawning streams throughout the 18th and 19th centuries, shad and herring had to negotiate a gauntlet of commercial fisheries erected each spring up and down the Potomac.. So prodigious were these runs that George Washington found it convenient to measure his fishery's sales in shillings per 100 shad and per 1000 herring. A commercial fishery once operated right from the Potomac shoreline of the Chapman's site and recorded yearly catches of American shad during the March-April spawning runs often exceeding 100,000 in the early 19th century. Today, remnant anadromous fish runs present but a thin shadow of their previous surges. ithin the Maryland portion of the Chesapeake Bay watershed, there are few streams with water quality relatively undegraded by runoff from farms, suburban and urban areas. When we find and look at such a stream, we see what we have lost through our neglect and, more importantly, what we must protect from rapidly encroaching destruction. The Mattawoman Creek in Charles and Prince Georges counties is such a stream. Build it and they won't come. Each spring, the dwindling remnants of once-mighty migratory fish populations seek out again the Chesapeake's fresh water streams in which they were born in. In their quest, species such American shad, blueback and alewife herring, and yellow and white perch have in the last century been increasingly thwarted, first as dams barred their way to ancestral spawning grounds, and then as their increasingly confined habitat was degraded by the effluent of human occupation. Retaining and protecting the quality of remaining freshwater estuarine and fluvial stream habitat for spawning and nursery grounds is crucial to the continued viability of these important fish stocks. The Mattawoman Creek has been identified by Maryland and the federal government as one of the most productive bass nurseries for in the northern Chesapeake Bay. Its headwaters rising just east of Route 301, Mattawoman Creek forms the border between Prince Georges and Charles counties for much of its length. West of Maryland Route 224, the creek becomes an estuary for the last seven miles of its length before flowing into the Potomac River just South of Indian Head. It is by now widely conceded that the health of the Chesapeake's aquatic ecosystem relies heavily on the quality of flow from feeder streams like the Mattawoman that, like roots, anchor the Bay to its watershed. A diverse array of aquatic life including both freshwater species, such as the migratory yellow perch and nonmigratory largemouth bass, and marine species, such as herring, shad, and stripped bass, use the Mattawoman for part or all of their life cycle. In the Chesapeake region, migratory species spawn from February through May, with exact timing dependent on species and stock and on other parameters, principally water temperature and stream flow. As with other migratory fish whose juveniles will summer in the tidal Mattawoman, eggs spawned in fluvial streams hatch into yolk-sac larvae with in two weeks to a month after fertilization (depending on temperature and species) and larvae consume their yolk sacs within a similar period. During this time, mortality is naturally high but can be profoundly exacerbated by human activity since eggs and larvae are especially susceptible to pollutants. Proposed destruction. The threat to the Mattawoman's water quality comes from a proposal to build a city of 15,000 on a 2250 tidewater wilderness site, called Chapman's forest, that nearly spans a pensula from the Potomac River to the creek. The site's deeply forested floodplains, wetlands, and perennial streams maintain the quality of both on-site and downstream waters important to a diverse array of aquatic life, At the same time, the site is riddled with steep slopes and is characterized by highly erodible soils, making it an especially potent source of downstream siltation if disturbed. Development of this tract on the planned scale would present a double-edged attack on aquatic life because not only would the current water-quality enhancing attributes be decimated, but they would be replaced with quality degrading factors, with severe consequences on spawning streams on the site itself and the tidal portion of the Mattawoman. According to studies by the EPA, North and South Carolina, and Delaware cited in a report commissioned by the Potomac River Association, at least five estuarine characteristics control tidal exchange between an estuary and the larger body of water with which it interacts: bottom slope, entrance configuration, tributary inflow, waterway shape, and range of tidal water levels. Mattawoman scores low on four of the five characteristics and only moderate on the fifth, tidal range. The tidal portion is fully 7 miles long, is narrow for much of this length, meanders dramatically, possesses very constricting bottlenecks, and exhibits shallow stretches that inhibit flow. Sediment runoff could dramatically impact fish populations in the Mattawoman estuary by increasing egg and larvae mortality by threatening the submerged aquatic vegetation. In addition to sediment from construction erosion, chronic increases in sediment would also occur from streambank erosion caused by increased volumes of stormwater runoff. Stormwater runoff is increased when forests, which through evapotranspiration return 60% of rainwater to the atmosphere, are clearcut. The problem is exacerbated when the clearcut is replaced by paved surfaces calculated to approach 20% for the Chapman project which not only prevents infiltration of rainwater, but funnels it into streams in damaging surges. Nutrients Sedimentation is only one of the threats posed to aquatic communities. Increases in excess nutrients from urban stormwater runoff threatens all fish species on several accounts. Right now, phytoplankton, i.e., microscopic suspended photosynthetic algae, are so dense in regional waters that they threaten other aquatic life. Because phosphorus is presently the limiting resource for phytoplankton growth in tidal Potomac waters increases can be expected to yield increased phytoplankton densities. Calculations based on development plans find that phosphorus loads from the Chapman's site would increase after buildout by 250% to 600%. Similarly, the loading of nitrogen from the site another water-born nutrient, and at 5 ppm (nitrate) one that is problematically high in the Mattawoman, will be increased by 160% to 200%. The dramatic increase in these nutrients can be expected to foster the phytoplankton-induced cloudiness that prevents light from nourishing the submerged aquatic vegetation. Finally, if the Chapman forest were replaced with a new city, multiplicative increases have been predicted for loadings of pesticides, metals such as zinc, copper, and lead, petroleum products, antifreeze, and road salt. The destruction produced by development like the one proposed for the Chapman forest reaches far beyond the perimeters of the site to the waters necessary for protecting Maryland's bays. At a time when there is so much money and attention being devoted toward restoring our waterways and protecting our fish, the State of Maryland has a responsibility to protect this precious resource.