Tag Archives: forecasting

MCWRS’s Workshop Discusses the Future of New England’s Rivers

On March 21, MCWRS hosted a free workshop on the future of New England’s rivers at the Springfield Water and Sewer Commission. Coalition members and non-members were invited to learn about these timely topics. Ed Capone, Service Coordination Hydrologist at the National Oceanic and Atmospheric Administration’s (NOAA) Northeast River Forecast Center (NERFC) presented his work forecasting river flows. The NERFC, one of 13 river forecast centers in the U.S., monitors Massachusetts’s six major river watersheds and works to protect life and property. At NERFC, Mr. Capone and the team calibrate and implement hydrologic and hydraulic models and produce temperature and precipitation forecasts to provide (1) river flow and stage forecasts, (2) guidance on the rainfall needed to produce flash flooding, (3) streamflow predictions, (4) ice jam and dam break support, and (5) water supply and reservoir inflow forecasts.

NOAA studies whole watersheds, and understands that its stakeholders, like the Coalition, are interested in an integrated approach to flooding, water quality, water availability, drought, and climate change, to understand both near- and long-term risks. Mr. Capone reported on observed trends in climate change, such as the increase in amounts and intensity of annual precipitation, warming annual temperatures, and extreme seasonal variations in snowfall that are trending, overall, downward in total amounts. Most notably, intense precipitation events (the heaviest 1%) have increased by 74% in the Northeast, the highest increase in the country. This is reflected in the rise in flooding frequency, especially minor flooding, for smaller watersheds and highly urbanized areas, as well as magnitude. Significant snow storms in the Northeast have also dramatically increased, particularly in the past decade. He explained that the amount of moisture in snow determines the amount of runoff, so a large storm of “dry” snow may have little impact. In terms of Massachusetts’s drought, Mr. Capone explained that drought periods are not uncommon and can happen despite an increase in rainfall.  One of the challenges in managing drought is that the definition can vary by state. He observed that a precipitation deficit may trigger water conservation measures when ground and surface water supplies are actually unaffected.

For Massachusetts and New England, the increase in flooding is related to more slow-moving storms, multiple events in close succession, and a tropical connection. New England’s proximity to Gulf and Atlantic moisture streams and the blocking effects of weather systems to the north play a role, as does even modest changes in ocean and air temperatures that allow the atmosphere to hold more water. The region has been a hotspot for record floods and rainfall over the past 10 years, along with increased yearly rainfall and annual temperatures.

Steven Wolosoff, Senior Environmental Scientist at CDM Smith, discussed the U.S. Environmental Protection Agency’s (EPA) Long Island Sound Nitrogen Reduction Strategy and its impacts in Massachusetts. Mr. Wolosoff explained that the issue is hypoxia, or low dissolved oxygen (DO), in the western portions of Long Island Sound (LIS) in the summer months, which affects bottom dwelling organisms that cannot move away from the area. A 1985 LIS study attributed hypoxia to increases in human wastewater, which led the agency to create a use impairment indicator and hierarchy evaluation system. The 2000 Total Maximum Daily Load (TMDL) study required specific actions, including a 58.5% reduction in nitrogen from in-basin (New York and Connecticut) sources from publicly-owned wastewater treatment plants (WWTP), and created a trading program. It also required that out-of-basin sources from Massachusetts, Vermont, and Canada reduce treatment plant contributions by 25%, nonpoint sources by 10%, and atmospheric deposition by 18%.

Since then, there has been a dramatic reduction of 51.5% in nitrogen contributions from Connecticut and New York WWTPs and the number of days with hypoxia has been reduced. Despite this, in 2015, the Connecticut Fund for the Environment petitioned EPA Regions 1 and 2 to develop a new or amended TMDL, stating that planned actions are not sufficient, climate change will worsen impairments in western LIS, nonpoint source treatment is insufficient, and there is new evidence of embayment impairments. EPA has moved forward with changes, focusing on additional nitrogen removal and addressing embayments Mr. Wolosoff noted that the changes to allowable nitrogen loads amount to a revised TMDL, not a reduction strategy.

Nitrogen sources include atmospheric deposition, wastewater treatment plant effluent, stormwater runoff, septic systems, agricultural runoff, and natural background (or ambient) amounts. EPA’s goal is to reach the natural, pre-colonial levels of nitrogen in LIS, which is not feasible or practical. All out-of-basin sources, including all Massachusetts sources, are already below pre-colonial levels. And, when attenuation is factored in, little benefit is derived from requiring additional controls. He added that the western LIS is most affected by hypoxia, yet Massachusetts’s contribution is to the eastern end. Also, links to local embayments are unclear.  The science indicates that sources in New York and Connecticut immediately adjacent to LIS are the dominant sources of nitrogen and dwarf inputs from other areas of New England. Mr. Wolosoff reviewed lower-cost options for reduction at treatment plants, but noted that stormwater Best Management Practices (BMPs) are more cost-effective than changes to WWTPs. The most effective BMPs appear to be yard waste pick up, street sweeping, and catch basin cleaning, which address the largest sources. When monitoring for DO, it’s important to note where samples are taken, as levels vary by depth, and should be conducted before and after measures are implemented. As the Coalition has noted previously, EPA has not engaged with Massachusetts stakeholders on what amounts to a TMDL revision that will significantly impact them.

You can learn about Nitrogen Trading at the Coalition’s 8th Annual Water Resources Strategies Symposium on May 17 in Marlborough. Stay tuned for future free workshops on other timely and regional topics.