Maine wetlands and waters: results of the National Wetland Inventory

              Cover photo by Ralph Tiner, U.S. Fish & Wildlife Service.

Maine Wetlands and Waters:

Results of the National Wetlands Inventory

June 2007

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Maine Wetlands and Waters:

Results of the National Wetlands Inventory

Ralph W. Tiner

U.S. Fish & Wildlife Service

National Wetlands Inventory Program

Northeast Region

300 Westgate Center Drive

Hadley, MA 01035

June 2007

This report should be cited as: Tiner, R.W. 2007. Maine Wetlands and Waters: Results

of the National Wetlands Inventory. U.S. Fish and Wildlife Service, Northeast Region,

Hadley, MA. NWI Technical Report. 22 pp.

Note: The findings and conclusions in the report are those of the author and do not

necessarily represent the views of the U.S. Fish and Wildlife Service.

TABLE OF CONTENTS

Page

Introduction 1

Study Area 1

Methods 4

Results 8

Wetland Maps 8

State Totals 10

County Totals 10

Discussion 18

Map Accuracy Assessment 18

Comparison with Hydric Soils Acreage 18

Conclusion 20

Acknowledgments 21

References 22

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1

INTRODUCTION

The U.S. Fish and Wildlife Service (FWS) has been conducting a nationwide survey of

wetlands and deepwater habitats since the mid-1970s through its National Wetlands

Inventory Program (NWI). This survey is accomplished using traditional

photointerpretation techniques to produces map and digital geospatial data on the status

of wetlands. The U.S. Geological Survey topographic maps serve as the base data upon

which boundaries of wetlands and deepwater habitats are delineated. Wetlands are

classified according to the FWS’s official wetland classification system (Cowardin et al.

1979) which has been adopted as the national standard for reporting on the status and

trends of U.S. wetlands by the Federal Geographic Data Committee

(http://www.fws.gov/stand/standards/wetlands.txt). Wetland mapping has been

completed for over 90% of the coterminous U.S., all of Hawaii, and 35% of Alaska. For

the Northeast, wetland mapping has been completed for 12 of the 13 states in the region;

all but New York have been completely mapped. As time permits, the FWS summarizes

the results of its NWI for geographic areas. Detailed state reports have been prepared for

several states (Connecticut, Delaware, Maryland, and New Jersey), while data summary

reports have been prepared for several other states in the northeastern U.S.:

Massachusetts, Vermont, Pennsylvania, and West Virginia.

Wetland mapping for Maine was completed several years ago. Updated mapping is being

done for the coastal region. This report provides a summary of the findings of the

previous work.

Study Area

The state of Maine encompasses over 35,000 square miles in the northeastern United

States. It ranks 39th among states in size and 40th in population. The state contains

30,862 square miles of land and 4,523 square miles of water (http://infoplease.com).

From a natural landscape standpoint, the state falls within three of Bailey’s ecoregions:

Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province,

Eastern Broadleaf Forest (Oceanic) Province, and Laurentian Mixed Forest Province

(Bailey 1995). Due to its glacial history, the state contains thousands of lakes and ponds

with Moosehead Lake and Sebago Lake being the most well-known. Among the more

prominent rivers are the Penobscot, Kennebec, Androscoggin, Saco, St. John, Allagash,

St. Croix (forming part of the state’s eastern border with Canada), and Piscataqua

(separating the state from New Hampshire). Maine’s coastal region in noted for its

irregular rocky shoreline which is 4,568 miles long or 7,039 miles long if the shorelines

of its 4,617 islands are included in the calculation (Conkling 1999). Politically, the state

is divided into 16 counties (Figure 1, Table 1).

2

Figure 1. Maine counties.

3

Table 1. Maine counties and their land and water area in square miles.

(http://en.wikipedia.org)

Land Area Water Area Total Area in

County (% of total) (% of total) Square Miles

Androscoggin 470 (94.6) 27 (5.4) 497

Aroostook 6,672 (97.7) 157 (2.3) 6,829

Cumberland 836 (68.7) 381 (31.3) 1,217

Franklin 1,698 (97.4) 46 (2.6) 1,744

Hancock 1,588 (67.5) 763 (32.5) 2,351

Kennebec 868 (91.2) 84 (8.8) 952

Knox 366 (32.0) 776 (68.0) 1,142

Lincoln 456 (65.1) 244 (34.9) 700

Oxford 2,078 (95.5) 97 (4.5) 2,175

Penobscot 3,396 (95.5) 160 (4.5) 3,556

Piscataquis 3,966 (90.6) 411 (9.4) 4,377

Sagadahoc 254 (68.6) 116 (31.4) 370

Somerset 3,926 (95.9) 169 (4.1) 4,095

Washington 2,569 (78.9) 686 (21.1) 3,255

Waldo 730 (85.6) 123 (14.4) 853

York 991 (78.0) 280 (22.0) 1,271

Total 30,864 (87.2) 4,520 (12.8) 35,384

4

METHODS

The NWI relies on photointerpretation of aerial photographs to locate and map wetlands

and deepwater habitats. For Maine, most of the aerial photography used was 1:58,000

color infrared captured in the spring of 1985 and 1986, with some photos acquired in

1983 and 1984. With this imagery, the target mapping unit for wetlands ranges between

1-3 acres. This means that most wetlands larger than three acres should be mapped and

that all wetlands are not mapped. Even with this target mapping unit established, it must

be recognized that aerial photointerpretation has limitations in terms of the types of

wetlands that can be readily identified (Tiner 1990, 1999) and that larger wetlands of

certain types will escape detection and be missing from the maps. These limitations are

generally outlined in Table 1, with other observations from recent updated mapping listed

in Table 2.

Wetlands were classified according to the FWS’s official wetland classification system

(Cowardin et al. 1979). The following categories were identified for wetlands and

deepwater habitats: system, subsystem, class, subclass, water regime, and a few special

modifiers (e.g., partly drained, dike/impounded, excavated, and farmed). The organic

soil modifier “g” was applied to Atlantic white cedar swamps (e.g., PFO4Bg) to highlight

them; the acid modifier “a” was applied to bogs (e.g., PSS3Ba). The “h” (impounded)

modifier was applied to many wetlands fragmented by roads as well as to diked wetlands.

Wetland maps were prepared following standard NWI mapping conventions (U.S. Fish

and Wildlife Service 1994, 1995). Data were digitized to create a geospatial database.

NWI data are posted on the web at NWI home page: http://www.fws.gov/nwi/. Data

were summarized by the NWI Mapping Support Center at Madison, Wisconsin. The

following conventions were employed:

• State and county boundaries were determined using the Geographic Data

Technology’s 1:100K states and counties layers. These were used due to

the lack of a consistent nationwide layer of boundaries at the 1:24,000

scale.

• All marine deepwater habitats (M1___) were removed from the analysis.

The decision to remove them from the analysis was made due to the lack

of validity of this acreage value. The marine system extends far beyond

the mapped area and is ended at 1:250K quad boundaries rendering the

acreage meaningless.

• Areas where county or state boundaries consisted of two-line waterbodies,

(i.e. rivers, streams) the boundary was identified and digitized directly

from a USGS 1:24,000 DRG.

The data was summarized by county and aggregated by state in two categories: 1)

system, subsystem, class, and subclass and 2) system and water regime. Any differences

in state and county totals are due to round-off procedures.

5

Table 1. Major NWI map limitations. (Adapted from Tiner 1999).

1. Target mapping unit – minimum size wetland that NWI is attempting to map which is

generally related to the scale of the imagery: 1-3 acres for 1:58,000 photography used in

the study area.

2. Spring photography – aquatic beds and nonpersistent emergent wetlands may be

undermapped since these types are usually obscured by high water. In some cases,

flooded emergents may be misclassified as scrub-shrub wetlands.

3. Forested wetlands – forested wetlands on glacial till are difficult to photointerpret as

are temporarily flooded or seasonally saturated types, especially on the coastal plain and

on glaciolacustrine plains; they may be underrepresented by the current NWI mapping.

Such areas may be identified by examining U.S. Department of Agriculture soil survey

maps for hydric soil map units that are undeveloped (i.e., areas of undeveloped hydric

soil map units that were not mapped by NWI represent areas that may contain wetlands).

4. Estuarine and tidal waters – delineation of the break between estuarine and riverine

(tidal) systems should be considered approximate; the irregular rocky shore of the coast

of Maine has complicated the delineation of the boundary between estuarine and marine

systems and such boundaries are also approximate.

5. Tidal flats – since imagery was not tide synchronized, tidal flat boundaries were based

on aerial photointerpretation in consultation with collateral data such as U.S. Geological

Survey topographic maps and Maine coastal geologic maps (Timson 1976).

6. Coastal wetlands – identification of high marsh (irregularly flooded) vs. low marsh

(regularly flooded) in tidal marshes is conservative; photo-signatures are not distinctive

in many instances.

7. Water regimes – water regime classification is based on photo-signatures coupled with

limited field verification; they should be considered approximate.

8. Linear wetlands (long, narrow) – they follow drainageways and stream corridors and

may or may not be mapped depending on project objectives. Most NWI maps identify at

least some of these features, but no attempt was made to map all of them.

9. Partly drained wetlands – they are conservatively mapped; many are not shown on

NWI maps.

10. Aerial photography – imagery reflects wetness during the specific year and season it

was acquired. Some photos for northern Maine were very dark making it difficult to

detect forested wetlands.

6

11. Drier-end wetlands (temporarily flooded and seasonally saturated types) – they are

difficult to photointerpret; many have been mapped by consulting hydric soil data from

the U.S.D.A. Natural Resources Conservation Service.

12. Mapped boundaries – they may be somewhat different than if based on detailed field

observations, especially in areas with subtle changes in topography.

7

Table 2. Some recent observations regarding limitations of prior Maine NWI mapping

for Downeast Maine (Huber 2006). These changes will be made to the updated NWI

maps; they were not made to the data referenced in this report.

1. Many wetlands mapped as PFO1 (palustrine broad-leaved deciduous forested wetland)

are actually dominated by larch (Larix laricina) and should be classified as PFO2 (2 =

needle-leaved deciduous).

2. Numerous smaller wetlands that occur in dips between rolling hills were not mapped.

3. Areas mapped as M2AB1N (algae-dominated rocky shores) appear to have less algae

than before and are better classified as M2RS1N and M2RS2N or mixes.

4. Significant tidal flow was observed through culverts connecting wetlands upstream

with marine wetlands downstream and many wetlands previously classified as palustrine

tidal wetlands should be reclassified as marine or estuarine types.

8

RESULTS

Wetland Maps

NWI maps for Maine were prepared for various location from the late 1970s to the

present. These maps were produced at a scale of 1:24,000 using the U.S. Geological

Survey topographic maps as base maps. Hardcopy maps are available for purchase

through the Maine Geological Survey (Publications), Augusta, ME 04333-0033 (Robert

Tucker, 207-287-2801).

After publication of the hardcopy maps, the NWI maps were converted to digital form for

computer access and geographic information system (GIS) applications. Since the 1990s,

the NWI Program has stopped production of hardcopy maps, replacing them with digital

wetland geospatial data. All NWI data are now available online at the NWI website:

http://www.fws.gov/nwi/. While the entire state was mapped by the late 1980s, some

areas (coastal region – New Hampshire border to Machias) have been updated with more

recent imagery. These newer data are only available online. To access NWI data, visit

the NWI website, click on the “Wetlands Mapper”, then click on the map of the lower 48

states, and finally zoom into the location of interest to see the wetland data for a specific

area. Digital NWI data can also be downloaded for GIS use at this website.

Figure 2 shows the distribution of wetlands and waters of Maine, excluding marine

waters. This figure is a reduction of the original map that was prepared at a scale of

1:450,000.

9

Figure 2. Map showing the distribution of wetlands and waters of Maine excluding

waters of coastal embayments and the Gulf of Maine. (Note: This is a reduced version of

original figure.)

10

State Totals

Wetlands. The NWI identified more than two million acres of wetlands, covering 10.3%

of the state’s land area (Table 3). Palustrine wetlands are the main type, totaling 1.9

million acres and representing 94% of the state’s wetland area. Fifty-nine percent of the

palustrine wetlands (or 56% of all wetlands) were forested types, with scrub-shrub

wetlands making up slightly more than one-quarter (28%) of the freshwater wetlands,

emergent wetlands representing 9% of these wetlands, and ponds (unconsolidated bottom

and shores) account for nearly 3%. Estuarine wetlands are second-ranked in area,

occupying roughly 69,000 acres which amount to slightly more than 3% of the wetland

area. Tidal flats (unconsolidated shores) were the most common estuarine wetlands,

accounting for 62% of the estuarine wetlands. Emergent wetlands (salt and brackish

marshes) made up 28% of the estuarine wetlands. Marine wetlands represented 2% of

the state’s wetlands. Rocky shores (including aquatic beds which are mostly algae-covered

rocky shores) accounted for 55% of these wetlands, while tidal flats

(unconsolidated shores) comprised nearly all of the remainder.

Deepwater Habitats. Over one million acres of deepwater habitats were inventoried,

excluding marine waters and waters of linear streams. Lacustrine waters accounted for

86% of the state’s water area (912,282 acres). Riverine waters were next in area with

87,293 acres mapped (6,722 tidal acres, 65,041 lower perennial acres, and 15,530 upper

perennial acres), followed by 53,491 acres of estuarine waters (including 11 acres of

eelgrass beds). It must be recognized, however, that marine waters dominate the state’s

waters but were not tabulated.

County Totals

Wetlands. The acreage of wetlands by type is given for each county in Table 4.

Aroostook County had the most wetland acreage with nearly 430,000 acres inventoried.

Five counties had over 200,000 acres: Aroostook, Penobscot, Washington, Piscataquis,

and Somerset. The wetlands in these counties accounted for 70% of the state wetlands

(the counties represent 67% of the state’s land area). The highest density of wetlands

was found in Sagadahoc County with nearly 21% of its land area occupied by wetlands

(Table 5). Eight other counties had more than 10% of their land area represented by

wetlands.

Deepwater Habitats. When marine waters are excluded, Piscataquis County had the

highest acreage of deepwater habitat (Table 6). This acreage was almost twice that of the

second-ranked county – Washington, which had nearly 130,000 acres of these

waterbodies. Nine percent of Piscataquis County was represented by water; this was the

highest percentage among counties. Kennebec closely followed with 8.7% of the county

being water, but this was attributed to only 53,000 acres of waterbodies. If marine

waters are counted, Knox County becomes top-ranked, closely followed by Hancock

County (Table 7). Washington County is the only other county with more than 500

square miles of water. Penobscot County dropped to ninth place in the ranking when

marine waters were included in the calculation.

11

Table 3. Wetland acreage summaries for the state of Maine. State totals differ from sum

of county totals due to round-off procedures. (Note: Marine and estuarine aquatic beds

are nearly all algae-covered rocky shores.)

Ecological System Wetland Class Acreage

Marine Aquatic Bed 18,950

Reef 15

Rocky Shore 3,200

Unconsolidated Shore 18,217

------------------------------ ------

Subtotal Nonvegetated 21,432

Total Marine 40,382

Estuarine Aquatic Bed 6,641

Emergent 19,653

Scrub-Shrub 9

------------------------------ ----------

Subtotal Vegetated 26,303

Rocky Shore 607

Unconsolidated Shore 42,933

------------------------------ ----------

Subtotal Nonvegetated 43,540

Total Estuarine 69,843

Palustrine Aquatic Bed 220

Emergent 179,496

Forested 1,133,591

Scrub-Shrub 541,108

----------------------------- -------------

Subtotal Vegetated 1,854,415

Unconsolidated Bottom 53,737

Unconsolidated Shore 736

------------------------------ -------------

Subtotal Nonvegetated 54,473

Total Palustrine 1,908,888

12

Table 3 (continued).

Lacustrine Aquatic Bed 94

Emergent (nonpersistent) 31

-------------------------------- -------------

Subtotal Vegetated 125

Rocky Shore 7,948

Unconsolidated Bottom 188

Unconsolidated Shore 7,446

--------------------------------- -------------

Subtotal Nonvegetated 15,582

Total Lacustrine 15,707

Riverine Aquatic Bed (tidal) 10

Rocky Shore (tidal) 4

Unconsolidated Shore (tidal) 475

Unconsolidated Shore 2,236

Rocky Shore 42

--------------------------------- -----------

Total Riverine 2,767

ALL WETLANDS 2,037,587

13

Table 4. NWI findings for each county. Numbers represent acres of wetlands.

County

NWI Type Androscoggin Aroostook Cumberland Franklin Hancock Kennebec Knox Lincoln

Palustrine Wetlands

Aquatic Bed -- 28 8 23 53 3 4 --

Emergent 2,874 24,517 3,862 5,092 11,695 7,911 2,343 5,332

Forested 15,227 303,000 20,856 27,196 48,735 24,999 9,616 18,691

Scrub-Shrub 5,850 90,739 9,323 15,837 33,870 14,923 4,638 8,513

Unconsol. Bottom 810 9,622 2,054 2,654 3,253 1,505 862 1,141

Lacustrine Wetlands

Aquatic Bed -- -- -- -- 70 -- 13 --

Unconsol. Shore 87 94 13 1 -- 25 -- --

Rocky Shore 1 -- -- -- 1 -- -- --

Riverine Wetlands

Unconsol. Shore -- 1,065 2 309 -- 125 12 128

Rocky Shore 25 3 -- -- -- 1 -- 1

Estuarine Wetlands

Aquatic Bed -- -- 61 -- 2,565 -- 485 889

Emergent -- -- 4,034 -- 1,015 -- 504 1,309

Unconsol. Shore -- -- 5,238 -- 8,675 -- 3,228 5,161

Rocky Shore -- -- 10 -- 321 -- 21 89

Marine Wetlands

Aquatic Bed -- -- 787 -- 7,687 -- 2,880 553

Unconsol. Shore -- -- 2,441 -- 3,164 -- 1,652 162

Rocky Shore -- -- 163 -- 1,446 -- 416 118

Reef -- -- -- -- 15 -- -- --

Total 24,874 429,068 48,852 51,112 122,565 49,492 26,674 42,087

14

Table 4 (continued). County

NWI Type Oxford Penobscot Piscataquis Sagadahoc Somerset Washington Waldo York

Palustrine Wetlands

Aquatic Bed 1 7 -- 39 33 1 3 15

Emergent 6,114 29,671 21,007 2,636 20,724 24,335 5,395 5,990

Forested 39,322 176,750 140,031 17,384 113,951 106,323 23,289 48,221

Scrub-Shrub 21,513 100,163 67,714 2,127 57,598 79,811 13,840 14,649

Unconsol. Bottom 2,699 6,976 6,543 555 5,908 5,182 1,652 3,059

Lacustrine Wetlands

Aquatic Bed -- -- -- -- -- -- -- 11

Emergent 31 -- -- -- -- -- -- --

Unconsol. Shore 18 5 3,829 -- 3,162 209 -- 3

Unconsol. Bottom 29 -- 1 -- 5 139 -- 14

Rocky Shore -- 531 6,295 -- 937 184 -- --

Riverine Wetlands

Unconsol. Shore 234 261 138 43 255 155 7 1

Rocky Shore -- 4 7 -- 3 -- -- --

Estuarine Wetlands

Aquatic Bed -- -- -- 143 -- 2,233 184 81

Emergent -- 4 -- 4,814 -- 3,471 422 4,089

Unconsol. Shore -- 180 -- 4,886 -- 11,882 718 2,965

Rocky Shore -- -- -- 49 -- 73 44 2

Marine Wetlands

Aquatic Bed -- -- -- 84 -- 4,463 1,827 669

Unconsol. Shore -- -- -- 578 -- 7,953 707 1,560

Rocky Shore -- -- -- 88 -- 833 103 35

Total 69,961 314,552 245,565 33,426 202,576 247,247 48,191 81,364

15

Table 5. Ranking of counties by wetland area. Percent of county comprised by wetlands

is also given.

Wetland Percent of County

Rank County Acreage Land Area

1 Aroostook 429,068 10.0

2 Penobscot 314,552 14.5

3 Washington 247,247 15.0

4 Piscataquis 245,565 9.7

5 Somerset 202,576 8.1

6 Hancock 122,565 12.1

7 York 81,364 12.8

8 Oxford 69,961 5.3

9 Franklin 51,112 4.7

10 Kennebec 49,492 8.9

11 Cumberland 48,852 9.1

12 Waldo 48,191 10.3

13 Lincoln 42,087 14.4

14 Sagadahoc 33,426 20.6

15 Knox 26,674 11.4

16 Androscoggin 24,874 8.3

16

Table 6. Acreage of deepwater habitats in Maine counties. Riverine waters are separated

into lower perennial, upper perennial, and tidal types. Percent of county occupied by

deepwater habitats (both excluding and including marine waters) is given.

Lacustrine Riverine Waters Estuarine Total % of County

County Waters Lower Upper Tidal Waters Waters (% w/Marine*)

Androscoggin 13,041 3,746 -- -- -- 16,787 5.3 (5.3)

Aroostook 78,724 14,789 6,758 -- -- 100,271 2.3 (2.3)

Cumberland 51,001 1,571 12 438 8,329 61,351 7.8 (31.3)

Franklin 28,838 1,479 436 -- -- 30,752 (2.8) (2.8)

Hancock 64,756 995 153 5 12,643 78,552 5.2 (32.5)

Kennebec 48,107 3,725 5 1,435 13 53,285 8.7 (8.8)

Knox 6,777 157 6 84 3,608 10,632 1.5 (68.0)

Lincoln 11,462 389 113 1,023 8,384 21,371 4.8 (34.9)

Oxford 56,395 5,311 338 -- -- 62,044 4.5 (4.5)

Penobscot 80,888 14,356 2,910 635 564 99,353 4.3 (4.5)

Piscataquis 245,315 5,283 1,717 -- -- 252,315 9.0 (9.0)

Sagadahoc 1,018 116 -- 2,958 2,958 7,050 3.0 (31.4)

Somerset 87,193 6,611 1,490 -- -- 95,294 3.6 (3.6)

Washington 113,557 3,406 1,445 143 10,913 129,464 6.2 (21.1)

Waldo 12,578 809 146 -- 2,731 16,264 3.0 (14.4)

York 10,630 2,300 1 -- 3,347 16,278 2.0 (22.0)

*Estimated.

17

Table 7. Ranking of counties by deepwater habitat area. Area is square miles.

County Nontidal Tidal Total

Waters Waters* Waters Rank

Androscoggin 26.2 -- 26.2 16

Aroostook 156.7 -- 156.7 10

Cumberland 82.2 298.8 381.0 5

Franklin 48.1 -- 48.1 15

Hancock 103.0 660.0 763.0 2

Kennebec 81.0 3.0 84.0 14

Knox 10.8 765.2 776.0 1

Lincoln 18.7 225.3 244.0 7

Oxford 97.0 -- 97.0 13

Penobscot 153.4 6.6 160.0 9

Piscataquis 394.2 -- 394.2 4

Sagadahoc 1.8 114.2 116.0 12

Somerset 148.9 -- 148.9 8

Washington 185.0 501.0 686.0 3

Waldo 21.1 101.9 123.0 11

York 20.2 259.8 280.0 6

*Area of marine waters was estimated.

18

DISCUSSION

Map Accuracy Assessment

A map accuracy investigation was performed for the area under jurisdiction of the Maine

Land Use Regulation Commission (LURC) in 1994 (Nichols 1994). The study involved

examining 1740 points along 90 transects in northwestern, northern, and eastern Maine.

All areas designated by NWI as wetlands or deepwater habitats were mapped correctly as

one or the other resource type. NWI maps identified over 90% of the wetlands greater

than 3 acres in size along the sample transects. For areas mapped as upland, 93-97% of

such areas were actually upland, with the rest largely being unmapped wetlands. The

total percent of sample points that were correctly mapped to resource type was 95.4%.

Some wetlands were included as uplands due to mapping conventions (e.g., minimum

mapping units) or misidentification. For areas mapped as wetlands, cover type

classification was correct for over 90% of the points examined, with most of the

discrepancies attributed to changes (e.g., beaver activity and human-induced impacts)

since the date of the aerial photographs used for the mapping.

If 7% of the area designated by NWI as upland is considered wetland, 1.24 million acres

should be added to the NWI wetland acreage for Maine. This would give Maine a total

of 3.28 million acres of wetlands, occupying an estimated 16.7% of the state.

Comparison with Hydric Soil Acreage

The U.S.D.A. National Resources Conservation Service has provided hydric soil acreage

summaries for surveyed areas in Maine which represent about 75% of the state (Table 8).

Hydric soils may cover 19% of the state, while the NWI mapping identified only 10% of

the state as wetland or nearly 17% if wetlands predicted on NWI uplands (based on the

Nichols study) are added to the mapped NWI wetlands. The difference is likely due to

both limitations of wetland photointerpretation and wetland alterations.

Photointerpretation has problems detecting certain evergreen forested wetlands in an

evergreen forest landscape matrix and identifying drier-end wetlands (those on soils with

seasonal high water tables, but not subject to flooding). The soil survey data also include

former wetlands such as drained hydric soils or hydric soils that are now developed (e.g.,

filled for commercial, industrial, or residential property). Overall, the NWI mapping is

conservative, while the hydric soil estimates are more liberal and don’t reflect recent

wetland losses (i.e., conversion of hydric soils to nonwetlands), so Maine’s current

wetland acreage may encompass about 17% of the state.

19

Table 8. Hydric soil data for Maine. Percent of survey area predicted to be covered by

hydric soil is also given. (Source: USDA Natural Resources Conservation Service)

County Area Acreage of % of

Surveyed (Acres) Hydric Soils Survey Area

Cumberland and part of Oxford

(689,331) 82,765 12.0

Kennebec (609,197) 98,077 16.1

Waldo (492,723) 84,323 17.0

York (656,844) 158,529 24.1

Knox and Lincoln (654,701) 98,790 15.1

Somerset-Southern Part (691,174) 185,994 26.9

Androscoggin and Sagadahoc

(512,275) 70,993 13.9

Aroostook – Northeast (1,554,443) 374,351 24.0

Aroostook – South (1,006,646) 320,175 31.8

Franklin and part of Somerset

(773,146) 94,916 12.3

Oxford (934,873) 86,825 9.3

Hancock (881,668) 123,202 14.0

Penobscot (1,501,216) 403,119 26.9

Piscataquis – South (687,000) 140,043 20.4

Washington (1,129,038) 225,911 20.0

Somerset and parts of Franklin and

Oxford (2,114,821) 289,911 13.7

Total Survey Area (14,889,206) 2,837,144 19.1

20

CONCLUSION

The NWI Program mapped about 2.04 million acres of wetlands and over 1 million acres

of deepwater habitats, excluding marine waters. The wetland mapping is conservative

due to limitations of the photointerpretation techniques employed. Considering NRCS

hydric soil data and the results of a wetland map assessment done for the LURC region,

the actual extent of wetlands in Maine is likely somewhere between 3.28 and 3.75 million

acres, representing 17-19% of the state’s land area.

21

ACKNOWLEDGMENTS

Numerous individuals contributed to the mapping of Maine’s wetlands. The Maine Land

Use Regulatory Commission (LURC) provided funding to inventory the lands under their

jurisdiction. Fred Todd (LURC) was instrumental in getting this area of the state mapped

by the NWI. The U.S.D.A. Natural Resources Conservation Service provided some

funding for work in the southwestern part of the state. Bob Wengynck assisted with this

support. Ralph Tiner coordinated this inventory for the U.S. Fish and Wildlife Service

(FWS).

Wetland photointerpretation for the mid-1980s survey was performed by staff at Geonex-

Martel Inc. (St. Petersburg, FL) including Joanne Weber, Charles Messenkopf, Tom

Kunneke, L. Cornell, and Toni Alese. The coastal areas and neighboring inland regions

were originally photointerpreted by the University of Massachusetts, Forestry and

Wildlife Department by John Organ, Frank Shumway, Tim Moore, and Anthony Davis,

with a few areas done by Jonathan Hall (Martel Laboratories). These late 1970s data

were updated.

Field review of draft maps was done by summer assistants including Susan Ziegler, E.

Davis, Bob Houston, Chris Hamilton, Chris Nichols, Matt Burne, and Irene Huber.

FWS personnel assisting in field review included Wende (Rosier) Mahaney, Gordon

Russell, Porter Reed, Norm Mangrum, Maurry Mills, Rene Whitehead, Glenn Smith, and

Ralph Tiner. Chris Nichols conducted an accuracy assessment of the maps which was

funded by LURC.

Glenn Smith (FWS) was responsible for providing regional quality control of the

inventory products, while Norm Mangrum and Rene Whitehead (FWS) provided national

quality control. Cartographic work was performed under the direction of the FWS’s

National Wetlands Inventory Center, St. Petersburg, Florida. GIS analysis of the data for

this report was done by Mitch Bergeson (U.S. Geological Survey) working for the NWI

Mapping Support Center at Madison, Wisconsin.

Paul R. Finnell, USDA Natural Resources Conservation Service, National Soil Survey

Center, Lincoln, Nebraska provided summaries of hydric soil data for Maine used to

prepare Table 9.

22

REFERENCES

Bailey, R.G. 1995. Description of the Ecoregions of the United States. U.S.D.A. Forest

Service, Washington, DC. http://www.fs.fed.us/land/ecosysmgmt/ecoreg1_home.html

Conkling, P.W. 1999. Islands in Time: A Natural and Cultural History of the Islands of

the Gulf of Maine. Island Institute, Rockland, ME.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of

Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service,

Washington, DC. FWS/OBS-79/31.

Huber, I. 2006. Field trip summary report for coastal Maine tier 2. University of

Massachusetts, Natural Resources Group, Amherst, MA.

Nichols, C. 1994. Map Accuracy of National Wetlands Inventory Maps for Areas

Subject to Land Use Regulation Commission Jurisdiction. U.S. Fish and Wildlife

Service, Hadley, MA. Ecological Services report R5-94/6.

Timson, B.S. 1976. Coastal marine geologic environment maps. Maine Geological

Survey. Open-file maps. 76-121.

Tiner, R.W., Jr. 1990. Use of high-altitude aerial photography for inventorying forested

wetlands in the United States. For. Ecol. Manage. 33/34: 593-604.

Tiner, R.W. 1999. Wetland Indicators: A Guide to Wetland Identification, Delineation,

Classification, and Mapping. Lewis Publishers, CRC Press, Boca Raton, FL.

U.S. Fish and Wildlife Service. 1995. Photo Interpretation Conventions for the National

Wetlands Inventory. NWI Project, St. Petersburg, FL.

U.S. Fish and Wildlife Service. 1994. Cartographic Conventions for the National

Wetlands Inventory. NWI Project, St. Petersburg, FL.

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U.S. Department of the Interior

Fish and Wildlife Service

http://www.fws.gov

June 2007