This interactive GIS map presents a graphic display of biological categories and groundwater withdrawal levels (formerly flow levels) developed through the SWMI process for the Massachusetts Water Indicators (MWI) 1400-scale subbasins. Clicking on the map image below will open the map viewer in another browser window, so you can follow the information provided on this page and also view the map. Below are links to the relevant USGS scientific investigation reports and supporting documents presented and summarized in these maps. This page and the map are works in progress, which will evolve to support stakeholders. SWMI materials are provided by SWMI staff from Executive Office of Energy & Environmental Affairs (EEA), Department of Conservation & Recreation (DCR), Department of Fish & Game (DFG)/ Division of Fish & Wildlife (DFW), and MassDEP.
More information is available below.
To use this interactive map: Beyond ease of access, the primary reason this is being presented as an interactive map is that there is simply too much information to present in a static map. Navagation tools are embedded in the left-hand side of the map. Click on the "About SWMI Data Viewer" located in the top right; then click on "Map Help" for further details. Here are some other key concepts to help navigate and find the information you are looking for.
- There are five significant layers of SWMI information presented; subbasins, biologic categories, groundwater withdrawal levels (GWL), water use points, and DFW's coldwater fishery resources. You can turn them on and off by clicking the check box by the layer title. Groundwater withdrawal levels and biologic categories cannot be viewed at the same time.
- The level of detail changes as you zoom in and out. It is impossible to have all data bearing labels at the state wide scale or anything close to it. Even as you zoom in, the map strives to place labels containing data so they do not overlap. If it cannot do that, it withholds some labels. You may have to zoom in very close to resolve conflicts due to the wealth of closely packed data.
- Finally, most of the information presented in a subbasin, or at a point is interpreted for the ENTIRE UPSTREAM WATERSHED. The user has to interpret the extent of that entire upstream watershed. Rivers and ponds are included in the map to help put this larger picture together.
Map Legend
Map Attributes
Major Basins
Refers to the major watersheds for 27 administrative basins in Massachusetts. All administrative units are labeled.
MWI subbasins
For nearly 1400 subbasins indicates the level of scale for the fish and flow analysis. White colored subbasins reflect "No Data" subbasins for the Connecticut and Merrimack River mainstems, the coasts and southeastern Massachusetts were excluded from the analysis due to substantially different hydrological conditions from the rest of the state. The MWI subbasins are described in USGS SIR 2009-5272.
Water use points
The water use points are derived from the Sustainable Yield Estimator (SYE) for the period 2000-2004. The water use points include public water supply (PWS)/water management (WMA) withdrawals, small public water supplies, water management (non-PWS) withdrawals, groundwater discharges (GWD), and surface water discharges (NPDES).
Coldwater Fishery Resource
The Coldwater Fishery Resource (CFR) source data is provided by the Department of Fish and Game's Division of Fish and Wildlife (DFW) and are presented as line segments over stream reaches.
Biological Category (BC)
Percent Alteration Color coded to reflect 5 categories of biological percent alteration of fluvial fish. BC categories of alteration ranges: 1 (0-5%); 2 (5-15%); 3 (15-35%); 4 (35-65%); 5 (>65%). Data revised 2012.
Groundwater Withdrawal Level (GWL) Percent Alteration
Color coded to reflect 5 groupings of percent of August median flow alteration. This is August flow alteration as related to groundwater withdrawals. The ranges for the percent of flow alteration are: 1 (0-3%); 2 (3-10%); 3 (10-25%); 4 (25-55%); 5 (>55%). Data revised 2012.
Fish Sampling Data Points
Fish Sample Data Points are shown as an orange circle accompanied by an ID number followed by the number of fluvial fish observed over the number of fluvial fish expected at that point. The numbers for both the "observed" and "expected" are defined as the catch-per-unit effort extended to one hour in time. Sample points are labeled as you zoom in. In order to resolve the data for points very close together, the user will have to zoom in quite a bit. Fish data is further described in USGS SIR 2011-5193.
Qualifier for the Fish Sampling Data Points
The fish data sampling point locations, along with the observed and expected values, were the result of a statewide statistical analysis reported in a recent USGS publication (SIR 2011-5193). This analysis illustrated a significant relationship between flow alteration, impervious cover, two natural basin characteristics, and fish community characteristics. The analysis used impervious cover and flow alteration calculated upstream of all fish sampling locations used in the report. Through the SWMI stakeholder process, it was determined that, in order to achieve the goal of establishing a statewide framework, the statistical relationship would be applied to the 1400-scale basin nodes (as if each basin node were a fish sample point). Analysis of the fish sampling points illustrated that increasing flow alteration and increasing impervious cover result in reductions in riverine fish numbers. The basin categorization then only illustrates which basins have higher impervious cover and flow alteration. Therefore caution is advised against misinterpreting fish sampling data points with subbasin color schemes.
Interactive Map Notes
The fish and habitat study, Factors Influencing Riverine Fish Assemblages in Massachusetts (2011) (USGS SIR 2011-5193 ), established a relationship between August flow alteration and biological integrity.
Biological Categories (BC) for the 1400-scale subbasins in the MA Water Indicators Project (USGS SIR 2009-5272) are based on a regression equation found in the USGS Report SIR 2011-5193 that included groundwater withdrawals.
Groundwater Withdrawal Levels (GWL) (formerly flow levels) for MA Water Indicators Project (USGS SIR 2009-5272) for the 1400-scale subbasins are based on groundwater withdrawals.
