Hydrologic Monitoring Program Highlights
Streamflows in the second half of December were mostly above normal, with some normal conditions, because of above-normal precipitation statewide. January streamflow was generally normal for the month. February through mid-March streamflows ranged from normal to below normal, because of below-normal precipitation for the period. Groundwater levels were generally normal throughout the winter. January levels were mostly normal, and some were above normal. February levels were mostly normal, and some were below normal.
Ice conditions were minimal in December and January; some anchor ice caused short-term backwater conditions in some locations. February ice conditions were significant, as temperatures were below normal for much of the month, leading to more anchor ice formation around the State than in recent years. By early March, all rivers and streams were clear of ice.
Massachusetts and Rhode Island
Surface-water conditions statewide in both Massachusetts and Rhode Island were normal to above normal in January, but by early March, conditions at western Massachusetts stations were below normal. These conditions prompted the State of Massachusetts to declare a level 1 mild drought in that part of the state on March 12, 2021. In Rhode Island, the U.S. Drought Monitor currently (March 25, 2021) indicates mild drought (level D0) conditions statewide.
The Maine Cooperative Snow Survey is a statewide, coordinated effort to measure the snowpack depth, water content, and density throughout the winter for flood forecasting. Go here for current Maine snow map.
Snow measurements are made with specialized snow equipment by citizen scientists, private companies, government agencies, clubs, and schools. The equipment is a tube called a Federal sampler that measures the depth and collects a core which is then weighed by using a snow scale calibrated to read in inches of water. The effort is jointly led by the U.S. Geological Survey (USGS) Maine office, the Maine Geological Survey, and the National Weather Service. Surveys are done monthly in January and February, then weekly from March until the snow is gone. While the primary purpose is flood forecasting, the data are also useful for monitoring long-term trends or for planning trips by field staff. For more information, go to: https://www.maine.gov/rfac/rfac_snow.shtml.
In winter months, river ice in Maine and other parts of New England can alter the relation that we develop between the level of the river and the discharge at that level. During this condition, known as backwater, we make discharge measurements through the ice to help us estimate the actual flow as we account for the influence of the ice. To do this, our staff drill up to 25-30 holes at each station, usually visiting 3-5 stations a day, which can make for a large number of holes.
New Hampshire and Vermont
According to the U.S. Drought Monitor, abnormally dry to moderate drought conditions persist through much of the New Hampshire part of the Connecticut River Valley, whereas the south-central and seacoast regions are abnormally dry. Streamflow conditions (as of March 16, 2021) were generally normal except for the seacoast region, which is below normal. Groundwater levels, as indicated by two long-term, real-time wells, showed period-of-record low water levels for March at well NH-SJW 2 in Shelburne, N.H. and normal water levels for March at well NH-WCW 1 in Warner, N.H.
In Vermont, the U.S. Drought Monitor currently (March 25, 2021) indicates conditions ranging from abnormally dry (D0) to moderate drought (D1) across the State. As of March 16, USGS streamflow conditions were found to be generally normal. Groundwater levels, as determined by three long-term USGS real-time wells during this period, showed conditions ranging from below normal to much below normal in the Vermont part of the Connecticut River Basin. Normal conditions were found for central Vermont, as determined by USGS well VT-PFW 8 in Pittsford.