Feast or Famine: Northeast Water Woes

Drought watches in Pennsylvania and New Jersey, flooding in New England, what's a river to do? No matter how much we try to alter natural conditions, Mother Nature always has the final word. 

June is National Rivers Month, a good time to contemplate the fates of our rivers and streams. Stream water quality can suffer when flows are either too high or too low. Freshwater streamflow to the Chesapeake Bay set a March record low in 2006, according to new data gathered by the U.S. Geological Survey. Streamflow to the Bay was about 65 percent below average. 

Low flows in small streams can negatively impact water quality when dilution is decreased and nutrient and pollutant levels become more concentrated. However, low flows mean fewer nutrients and sediments reaching larger water bodies, which can have a positive effect on the water quality in downstream lakes and reservoirs, as well as ocean bays. According to the Chesapeake Bay Program, "if the low-river flow conditions continue [during 2006], the reduced amount of freshwater flowing into the Bay can impact its water quality, habitats and aquatic life. Most noticeably, scientists associate “low flow conditions” with reduced amounts of nutrients and sediments entering the Bay as well as higher salinity levels in the Bay's waters. Reduced nutrient and sediment loads could result in improved water-quality conditions for fish, crabs, and underwater grasses this summer. Higher salinities could result in making oysters more susceptible to disease and impact fresh-water species of underwater grasses. And for swimmers, higher salinities allow sea nettles to show up earlier in the summer and move further north in the Bay." Based on an analysis of spring weather conditions and twenty years of Chesapeake Bay monitoring data, the ecological forecast for the Bay anticipates the annual return of oxygen-deprived “dead zones” in the Bay’s deeper waters, slight increases in beneficial underwater grasses and a moderately-high likelihood of harmful algal blooms on the tidal Potomac River. http://www.depweb.state.pa.us/news/cwp/view.asp?Q=507111&A=3 

On the opposite end of the spectrum, some areas of the northeast have experienced record rainfall this spring, leading to flooding in many New England and Northern New York rivers. At a recent New England Interstate Pollution Control Commission conference in Burlington, Vermont, flooding was a major topic of discussion. At the VT DEC, the water quality, engineering, and fish and wildlife departments related to streams have all merged into one department, the River Management Program, in order to maximize their cooperation and communication potential and improve effectiveness. In a presentation on the VT DEC's Fluvial Erosion Hazard Program, conference attendees learned that Vermont's goal is to move away from the National Flood Insurance Program (NFIP) mapping as the only means of determining flood hazard potential. Most flood damage in Vermont, and in many other states, isn't necessarily caused by floodplain inundation, but rather by eroded roads, bridges, and dams. Since the NFIP maps predict the flood hazard potential by innundation, certain areas that are at risk of flood damage due to rivers changing course and streambank erosion  are not being detected under the current system. VT DEC's new program encourages floodplain protection, reducing stream encroachments, and river corridor preservation as a means of reducing flood damage. They are developing a package of incentives for towns in the form of grants and loans to encourage cooperation with the program. A new agenda of the program is to map and restore floodplains to allow stream channels to self-stabilize. In the event of high flows, this will allow the energy in floodwaters to dissipate within the floodplan rather than causing major downstream damage. For more information on the Vermont DEC River Management Program, visit http://www.anr.state.vt.us/dec/waterq/rivers/docs/rv_programoverview.pdf  or contact a member of the River Management Section.

For more information on the design of floodplain restoration, streambank stabilization, or stream fluvial geomorphology assessment projects, contact F. X. Browne, Inc. at info@fxbrowne.com.