Maine Stream Habitat Viewer

Some layers have so many data points that displaying them while zoomed-out would cause the Viewer to load very slowly. These layer names will be in gray text and unable to display until you zoom-in enough.

First, check that you have a good internet connection. Second, try opening the Viewer in a different web browser. If that doesn’t work, please email the Habitat Viewer Project Manager using the Viewer’s list of contacts. Please provide in the email the name and version number of your web browser.

Unless they are severely degraded, all streams support some fish and/or wildlife species and may also have other important functions. The Viewer provides information for only a handful of Maine’s stream species. Also, many streams have not been surveyed, so even the data for our featured species is likely incomplete. We encourage you to use the list of expert contacts to learn more about the habitat values in their area of interest.

Privately owned crossings are counted along with public crossings when determining the total numbers of barriers upstream or downstream of a feature. However, private crossings are not displayed on the map unless the owner has given express permission for their crossing data to be displayed. The number of upstream and downstream barriers reported includes dams, natural barriers and impassable waterfalls. Also, in rivers or streams with tributaries, all mainstem dams will be included in the number of downstream barriers. For these reasons, there’s sometimes a mismatch between the number of barriers reported vs displayed upstream or downstream.

The Habitat Viewer includes both Potential Barriers and Barriers when calculating the total number of "Upstream Barriers" or "Downstream Barriers" reported in the pop-up box. Most Potential Barriers are often undersized, so, like designated "Barriers", Potential Barriers often should be replaced if the aim is to restore fish passage and stream health.

There may be several possible reasons. The first is that, with over 25,000 crossings in Maine, we haven't yet completed surveys of the entire state. Also, we don’t display data for private crossings unless granted permission by the landowner. And survey crews are not able to reach every site. Feel free to contact our training contacts if you would like to help with a survey.

Sometimes the streams are so small they don't show up on the basemap you are using. Try using the Imagery or USA Topo basemap. There is also the possibility that the displayed crossing has the wrong coordinates, in which case, please inform the GIS and Database Manager.

Natural barriers include waterfalls, beaver dams and wood debris jams. These are all natural impediments to the movements of fish and other aquatic wildlife. At each natural barrier, we measure how much of a vertical drop there is and assign a severity category. Waterfalls differ based on their height, steepness and structural diversity. Some beaver dams can also block fish movement; others are more porous and allow various degrees of passage. Wood debris jams also differ in how they affect aquatic passage, with loose jams of trees and branches usually being very passable. We conducted surveys of all possible natural barriers on some streams, but it is very time consuming. For most streams we only surveyed natural barriers that were near a crossing or dam that we were already surveying.

Not always. For instance, if maintenance costs and public safety are your primary concern, a severely undersized culvert that can’t adequately accommodate stream flows might be a top priority, even though it’s designated as a Potential Barrier versus a Barrier. We encourage you to use our contacts list to learn more about your area of interest and what options might best meet your needs.

Contacts:
Road Crossing Replacement: Casey Clark - Department of Marine Resources
Road Crossing Data: alexoabbott@hotmail.com - Gulf of Maine Coastal Program, U.S. Fish and Wildlife Service

These data were collected at public road, trail and railroad crossings in select watersheds starting in 2007. Data for crossings on private roads are not provided by the Stream Habitat Viewer without the express approval of the landowner. A wide range of cooperating organizations used survey methods developed by the U.S. Fish and Wildlife Service Gulf of Maine Coastal Program and its partners and were supported by funding from state, federal and nongovernment organizations. Descriptions of the legend categories are:

• Barrier: The crossing has physical factors that significantly restrict upstream passage of aquatic organisms and fishes, such as perching above the stream surface, as well as downstream movement of materials that create and maintain habitat.
• Potential Barrier: The barrier has physical factors that likely limit upstream passage of various aquatic organisms and downstream movement of materials that create and maintain habitat. The crossing shows signs of excessive current velocities, like scour. Excessive velocities can block fish and wildlife passage and are frequently caused or exacerbated by undersized culverts.
• No Barrier: neither of the above conditions was observed at the crossing.
• Unknown: survey crew could not access these sites.

Contacts:
Dam removal or fish passage: Casey Clark - Department of Marine Resources
Dam Data: alexoabbott@hotmail.com - Gulf of Maine Coastal Program, U.S. Fish and Wildlife Service

These data were compiled by the US Fish and Wildlife Service Gulf of Maine Coastal Program from field surveys and from the Maine Department of Environmental Protection’s dam database. Note that many dams have not yet been mapped and do not appear in this database. For some dams, not all attribute data (e.g. alewife acres blocked) are available. Descriptions of the legend categories are:

• Barrier: the dam blocks most if not all passage of fish and wildlife and their access to habitat that supports key phases of their life cycle.
• Potential Barrier: the dam blocks some species while others may achieve passage during some flows where fishways have been installed or where the dam is partially breached. Fishways are designed for passage of a narrow range of species and often do not allow passage at all flows.

Contact: alexoabbott@hotmail.com - Gulf of Maine Coastal Program, U.S. Fish and Wildlife Service

These data were compiled by the US Fish and Wildlife Service Gulf of Maine Coastal Program from field surveys and from the Maine Department of Environmental Protection’s dam database. Note that many dams have not yet been mapped and do not appear in this database. For some dams, not all attribute data (e.g. alewife acres blocked) are available. Descriptions of the legend categories are:

• Barrier: the dam blocks most if not all passage of fish and wildlife and their access to habitat that supports key phases of their life cycle.
• Potential Barrier: the dam blocks some species while others may achieve passage during some flows where fishways have been installed or where the dam is partially breached. Fishways are designed for passage of a narrow range of species and often do not allow passage at all flows.

Contact: alexoabbott@hotmail.com - Gulf of Maine Coastal Program, U.S. Fish and Wildlife Service

Data describing locations of waterfalls that block most if not all passage of fish and aquatic wildlife and where no records indicate passage was historically possible. Data were collected during field surveys or compiled by fisheries biologists of the Maine Department of Inland Fisheries and Wildlife and Maine Department of Marine Resources. This dataset is not complete, but represents the opinion of state biologists.

This dataset provides Atlantic salmon spawning habitat locations from surveys conducted by field biologists within and outside of the Gulf of Maine Atlantic salmon Distinct Population Segment. The surveys were intended to document the presence of adequate habitat, not the presence of Atlantic salmon using the habitat. Categories in the legend are Limited Spawning and Spawning.

This dataset provides Atlantic salmon rearing habitat locations from surveys conducted by field biologists within and outside of the Gulf of Maine Atlantic salmon Distinct Population Segment. The surveys were intended to document the presence of adequate habitat, not the presence of Atlantic salmon using the habitat.

This habitat layer predicts the proportion of stream reaches containing Atlantic salmon rearing habitat within the Gulf of Maine Atlantic salmon Distinct Population Segment. The model uses 1) slope for stream reaches that are derived from contour and digital elevation model datasets, 2) cumulative drainage area, and 3) physiographic province, to identify stream reaches that have similar characteristics to areas where field crews have identified Atlantic salmon rearing habitat. Given the predicted values, the legend categories are not distributed across the entire 1-100% range. Categories in the legend are:

• Class 1: Prediction that >50% of modeled reach is suitable habitat.
• Class 2: Prediction that 26-50% of modeled reach is suitable habitat.
• Class 3: Prediction that 10-26% of modeled reach is suitable habitat.

More information on the model can be found in the report: Wright, J., Sweka, J., Abbott, A., & Trinko, T. (2008). GIS-based Atlantic salmon habitat model. A PDF of the report is available here.

Contact: Dan Tierney (dan.tierney@noaa.gov) – National Oceanographic and Atmospheric Administration Fisheries Service

This layer shows the HUC 10 watersheds that have been classified as Critical Habitat under the Endangered Species Act for the Gulf of Maine Atlantic salmon Distinct Population Segment. The National Marine Fisheries Service defines critical habitat as “the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and outside the geographical area occupied by the species if the agency determines that the area itself is essential for conservation”.

Contact:  Dan Tierney (dan.tierney@noaa.gov) – National Oceanographic and Atmospheric Administration Fisheries Service

This layer depicts the boundary of the Gulf of Maine Atlantic salmon Distinct Population Segment (DPS) and the three recovery units (Penobscot, Merrymeeting, and Downeast) within the DPS.

This dataset provides historical and current information on habitat that was documented by the Department of Marine Resources. Legend categories describe run status as:

• Accessible: the latest data indicate the run is active, with a self-sustaining population that is able to reach their spawning grounds without assistance.
• Accessible – DMR stocked: the latest data indicate the run is active, with a self-sustaining population that is supplemented by alewives stocked by DMR. These locations may not have been stocked in the most recent year but have been stocked one or more years since 2010.
• Inaccessible – DMR Stocked: there is evidence that a run existed historically, but passage is currently blocked. The run is active only because of efforts to truck fish around the impediment or stock from a permitted source by DMR in one or more years since 2010. If the obstruction that presently blocks passage is removed a self-sustaining run is possible.
• Inaccessible - Not Stocked: there is evidence that a run existed historically, but no longer exists because of a passage obstruction, and if the obstruction that presently blocks passage is removed, a rejuvenated run is possible.
• Stream: shows the upstream and downstream passageways of alewife to and from their spawning locations and marine waters.

Note: clicking the displayed stream or pond (spawning) habitat will provide status, harvest information, stream or pond name and pond acreage. All lakes and pond upstream of a harvest location will be listed as “Commercially Harvested” because the mainstem run is subject to harvest.

This dataset indicates the likelihood of an active run in waters where no previous documentation of a self-sustaining alewife run is available. Legend categories describe the likelihood of potential habitat as:

• Accessible: no passage obstructions would prevent alewife passage to spawning lakes and ponds, but there is no conclusive evidence that a current run exists.
• Accessible – DMR Stocked: these are waters that have the capacity for alewife runs, but where a self-sustaining run has not been conclusively documented. These waters have been stocked by DMR in one or more years since 2010.
• Uncertain: for waters thought to have the capacity for alewife runs in the past, but where passage is presently obstructed or a self-sustaining run has not been conclusively documented.
• Stream: shows the upstream and downstream passageways of alewife to and from their spawning locations and marine waters.

Note: clicking the displayed stream or pond (spawning) habitat will provide status, harvest information, stream or pond name and pond acreage. All lakes and pond upstream of a harvest location will be listed as “Commercially Harvested” because the mainstem run is subject to harvest. In many of these cases, the harvest is located on a mainstem river.

The Smelt Productivity layer describes the run status at streams where the presence of sea-run (anadromous) rainbow smelt was observed. For each run, the upstream extent of the stream section displayed represents the expected upstream extent of spawning. Legend categories follow:

• High: spawning was confirmed by the presence of adult smelt or smelt eggs in large numbers and multiple years during the 2005-2009 period, and some observations during 2012-2014, with no known decline from historical numbers.
• Limited: includes runs where either 1) spawning was confirmed by the presence of adult smelt or smelt eggs in one or more years 2005-2009, and some observations during 2012-2014, but not in great numbers or not in every year or 2) runs confirmed by the presence of adult smelt or smelt eggs in one or more years 2005-2009, and some observations during 2012-2014, but in numbers markedly reduced from historical numbers, based on DMR records or local knowledge.
• Declining: observations of these runs during spawning events in one or more years 2005-2014 found fewer smelt egg density or fewer adults than was observed in surveys performed in 1971.
• Uncertain: known spawning site in 1971 or modeled spawning site in 1984, but current status was not confirmed.
• Smelt access route: these lines are provided to draw attention to stream reaches and water bodies that are vital to smelt accessing upstream spawning habitat.

This layer corresponds to sites that have the potential for spawning because of habitat type or because they supported historical runs. Legend categories follow:

• Potential: not listed in 1971 DMR records and not modeled in 1984, but checked in one or more years 2005-2009, with no spawning activity observed.
• Historical: the site supported smelt spawning in surveys in 1971 and prior, but was no longer found to support spawning during 2005-2009 surveys, and some observations during 2012-2014.
• Smelt access route: draws attention to stream reaches and water bodies that are vital to smelt accessing upstream spawning habitat.

Contact: merry.gallagher@maine.gov - Maine Department of Inland Fisheries and Wildlife

This habitat layer represents all lakes and ponds designated by the Maine Department of Inland Fisheries & Wildlife and approved by the Maine Legislature as Maine Heritage Fish Waters. These waters contain Maine Heritage Fish, wild Eastern Brook Trout or Arctic Charr, that have never been stocked or have not been stocked for at least 25 years.

Contact: merry.gallagher@maine.gov - Maine Department of Inland Fisheries and Wildlife

For regional freshwater fishery management questions, including those related to barrier removals, contact:
Region A - Sebago Lake area - James Pellerin, james.pellerin@maine.gov
Region B - Belgrade Lakes area - Jason Seiders, dwayne.j.seiders@maine.gov
Region C - Downeast area - Greg Burr, gregory.burr@maine.gov
Region D - Rangeley Lakes area – Liz Latti, elizabeth.latti@maine.gov
Region E - Moosehead Lake area - Tim Obrey, tim.obrey@maine.gov
Region F - Penobscot River area – Kevin Dunham, kevin.dunham@maine.gov
Region G - Aroostook Fish River area - Frank Frost, frank.frost@maine.gov

This layer was derived from an updated Eastern Brook Trout Joint Venture model based on U.S. Geological Survey catchments. A catchment is the surface area contributing drainage directly to a given section of stream known as a “reach”. Catchments displayed in this layer are based on known occurrences through MDIFW survey efforts of wild eastern brook trout (WEBT) and assumptions about access, passability and distance. Areas where MDIFW actively manages for WEBT priorities are also included. Blank areas indicate that WEBT status is either unknown or is not a current MDIFW management priority.

Contacts: Kristen Puryear, kristen.puryear@maine.gov - Maine Department of Agriculture, Conservation and Forestry, Maine Natural Areas Program

The tidal marsh dataset includes wetlands classified by the National Wetlands Inventory as Estuarine and Riverine Emergent Wetlands, which can range from saline to fresh. This layer is incomplete in some cases, especially in large tidal systems like Merrymeeting Bay in the Kennebec River Estuary. Maine’s tidal marshes represent a small fraction of the total wetland acreage in Maine. Yet they provide habitat for diverse fish and wildlife species and a wide range of benefits to people, like coastal storm protection, carbon capture, fishery support, and harvesting opportunities. Where road crossings or dams are built on tidal marshes, health of the upstream wetland is almost always impacted, regardless of the structure's designated barrier status in the Stream Habitat Viewer. Maine Coastal Program’s Tidal Restriction Atlas provides the most current and complete information on structures in Maine tidal environments: https://www.arcgis.com/apps/webappviewer/index.html?id=8f7fc922c464482d8fe946ca5b17c7ea

This layer provides known and assumed locations of non-native fish species. Non-native fish species, sometimes called "invasive", can outcompete native species that are highly valued in Maine. Non-native species include black crappie, largemouth bass, smallmouth bass, muskellunge, northern pike, and walleye. Barriers like dams and road crossings can block the spread of non-native fish, so barrier removals should be considered in light of adjacent non-native species concerns. However, concerns about the spread of invasives are often subordinate to restoration goals. Legend categories are "Documented" and "Potential".

Contact: merry.gallagher@maine.gov - Maine Department of Inland Fisheries and Wildlife

For regional freshwater fishery management questions, including those related to barrier removals and non-native species, contact:
Region A - Sebago Lake area - James Pellerin, james.pellerin@maine.gov
Region B - Belgrade Lakes area - Jason Seiders, dwayne.j.seiders@maine.gov
Region C - Downeast area - Greg Burr, gregory.burr@maine.gov
Region D - Rangeley Lakes area – Liz Latti, Elizabeth.Latti@maine.gov
Region E - Moosehead Lake area - Tim Obrey, tim.obrey@maine.gov
Region F - Penobscot River area – Kevin Dunham, kevin.dunham@maine.gov
Region G - Aroostook Fish River area - Frank Frost, frank.frost@maine.gov

Contact: donald.katnik@maine.gov - Maine Department of Inland Fisheries and Wildlife

Waterfowl (ducks, geese, swans) and wading birds (herons, egrets, bitterns, ibises, coots, moorhens and rails) require certain types of tidal wetland habitat for feeding, roosting, nesting and brood rearing. Both high and moderate value Tidal Waterfowl and Wading Bird Habitat are defined as Significant Wildlife Habitat under Maine's Natural Resources Protection Act. Maine Department of Inland Fisheries and Wildlife has identified and rated intertidal areas along the coast as high or moderate value to waterfowl and wading birds. Tidal waterfowl and wading bird habitat includes only the mapped habitat within the coastal wetland, which is already regulated as a protected natural resource under the NRPA.

Contact: donald.katnik@maine.gov - Maine Department of Inland Fisheries and Wildlife

This layer represents high and moderate value Inland Waterfowl and Wading Bird Habitat, both defined as Significant Wildlife Habitat defined under Maine's Natural Resources Protection Act. Maine Department of Inland Fisheries and Wildlife has identified significant inland habitats for ducks, geese, herons, and associated species of waterfowl and wading birds throughout the state, rating them as having high to moderate value. A high to moderate value inland bird habitat is a complex of freshwater wetland and open water areas plus a 250-foot wide area surrounding the complex itself where some species nest. On “great ponds” (over 10 acres), only the upland area that is within 250 feet of the freshwater wetland is included as part of this bird habitat.

Layer: Beginning with Habitat Focus Areas

Contact: Steve.Walker@maine.gov - Maine Department of Inland Fisheries and Wildlife

For questions regarding the data and cartography, contact: Steve.Walker@maine.gov - Maine Department of Inland Fisheries and Wildlife

Beginning with Habitat Focus Areas are natural areas of statewide ecological significance that contain unusually rich concentrations of at-risk species and habitats. These areas are identified by biologists from the Maine Natural Areas Program, Maine Department of Inland Fisheries and Wildlife, Maine Department of Marine Resources, U.S. Fish and Wildlife Service, The Nature Conservancy, Maine Audubon and Maine Coast Heritage Trust. Focus Areas support rare plants, animals, and natural communities; high quality common natural communities; Significant Wildlife Habitats; and their intersections with large blocks of undeveloped habitat. Beginning with Habitat Focus Area boundaries are drawn based on the species and natural communities that occur within them and the supporting landscape conditions that contribute to the long-term viability of the species, habitats and community types.

One or more of the following must be present before an area is considered a Candidate Focus Area (in most cases, two or more are present):

• Globally rare plant or animal
• 3 or more healthy populations of a rare plant species
• Any healthy population of a rare animal species
• Rare natural community
• Excellent example of a common natural community
• Good example of a common natural community and one or more high value wildlife habitats
• Large undeveloped block and at least one of the following: a good example of a common natural community OR high value wildlife habitat OR two or more healthy populations of a rare plant species