Classification for Landscape Level Wetland Functional Assessments in the Rocky Mountains

May 2015

CNHP’s mission is to preserve the natural diversity of life by contributing the essential scientific foundation that leads to lasting conservation of Colorado's biological wealth.

Colorado Natural Heritage Program Warner College of Natural Resources Colorado State University 1475 Campus Delivery Fort Collins, CO 80523 (970) 491-7331

Recommended Citation: Sueltenfuss, J. and J. Lemly. 2015. Classification for Landscape Level Wetland Functional Assessments in the Rocky Mountains. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.

Front Cover: Routte National Forest fen dominated by Salix wolfii and Eleocharis quinqueflora. © Colorado Natural Heritage Program

Southern Rockies Classification for Landscape Level Wetland Functional Assessments

A revised LLWW Classification for the Southern Rockies Landscape

Jeremy Sueltenfuss Joanna Lemly Colorado Natural Heritage Program Warner College of Natural Resources

Colorado State University Fort Collins, Colorado 80523

April 2015

ACKNOWLEDGEMENTS

The authors would like to acknowledge the U.S. Environmental Protection Agency (EPA) Region 8 and Colorado Department of Transportation (CDOT)’s Wetlands Program for their financial support and encouragement of this project. Of course, we are building off of an existing classification, so many thanks for the groundbreaking work by Ralph Tiner and the US Fish and Wildlife Service’s National Wetlands Inventory.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments i TABLE OF CONTENTS

Acknowledgements ...... i Introduction ...... 1 Need for LLWW Classification Specific to the West ...... 1 Notable Differences from LLWW Version 3.0 (Tiner 2014) ...... 2 Southern Rockies LLWW Coding System ...... 2 Coding for Wetlands ...... 4 Lentic Wetlands ...... 5 Lotic Wetlands ...... 5 Terrene Wetlands ...... 5 Flow Paths ...... 5 Modifiers ...... 6 Coding for Waterbodies ...... 7 Lakes and Ponds ...... 7 Rivers ...... 8 Modifiers ...... 8 Using the Southern Rockies LLWW Key ...... 9 Examples of LLWW Attributed Wetlands ...... 9 Lotic Fringe/Lotic Island ...... 9 Lotic Floodplain ...... 10 Lotic Basin ...... 10 Lotic Slope ...... 12 Terrene Slope Outflow (headwater wetlands discharging to stream) ...... 13 Terrene Basin ...... 14 Lentic Fringe ...... 15 Examples of LLWW Attributed Waterbodies ...... 16 Terrene Outflow Lake ...... 16 Terrene Vertical Flow Pond ...... 17 Lotic Through flow Lake ...... 18 Key to the Southern Rockies LLWW ...... 19 References ...... 25

TABLE OF FIGURES

Figure 1. Lotic Fringe and Lotic Island wetlands...... 9 Figure 2. Lotic Floodplain wetlands...... 10 Figure 3. Lotic Basin wetland as a fully vegetated channel with no flowing water...... 11 Figure 4. Lotic Basin wetland as a channel with very slow moving water ...... 11 Figure 5. Lotic slopes as an irrigated field...... 12 Figure 6. Lotic Slope wetlands created from seepage from canals ...... 12 Figure 7. Terrene Slope Outflow headwater wetlands...... 13 Figure 8. Terrene Basin wetlands ...... 14 Figure 9. Lentic Fringe Wetlands ...... 15 Figure 10. Terrene Outflow Lake ...... 16 Figure 11. Terrene Vertical Flow Pond ...... 17 Figure 12. Terrene Vertical Flow pond in dry channels...... 17 Figure 13. Lotic Through flow Lake ...... 18

TABLE OF TABLES

Table 1. LLWW Landscape Position codes and interpretation...... 3 Table 2. LLWW Landform codes and interpretation...... 3 Table 3. LLWW Water Flow Path codes and interpretation...... 3 Table 4. LLWW Waterbody codes and interpretation...... 4 Table 5. LLWW Classification for Wetlands ...... 4 Table 6. LLWWClassification for Waterbodies ...... 7

Southern Rockies Classification for Landscape Level Wetland Functional Assessments iii

INTRODUCTION

The U.S Fish and Wildlife Service’s National Wetland Inventory (NWI) program originally mapped Colorado’s wetlands and waterbodies in the 1970s and 1980s. The Colorado Natural Heritage Program (CNHP) has been digitizing original NWI maps since 2008, with the entire state completed in 2014. Widespread land use changes in the last 30+ years, along with substantial increases in the quality of aerial images and mapping methods necessitates an update to the NWI maps. As such, CNHP has completed wetland mapping for various portions of the state using recent aerial photography, and is continually looking for new areas and project partners to complete new mapping. As part of new mapping, CNHP has begun attributing wetlands with both the NWI Cowardin Classification (Cowardin et al. 1979), as well as with the Landscape, Landform, Water Flow Path, and Waterbody (LLWW) classification developed by the US Fish and Wildlife Service (Tiner 2003) to provide information on possible wetland functions similar to the Hydrogeomorphic classification (Brinson 1993). This report provides an introduction, description, and set of dichotomous keys to a revised LLWW classification developed by CNHP to be used specifically within the Southern Rockies Landscape.

Need for LLWW Classification Specific to the West

The LLWW classification has been continually revised since its creation to address the new types of wetlands encountered in landscapes where LLWW is employed. A significant difference exists in wetland types across the country, necessitating a certain level of regionalization of the LLWW framework. CNHP decided to develop an LLWW classification specific to the Southern Rockies Landscape, to be of particular use in Colorado and up through Montana, in an effort to simplify and specify the classification for our needs.

Because the original LLWW was created for use in the north east portions of the Unites States, the application of the original classification in the west was difficult due to a few prominent differences in wetland hydrology, ecology, and geography, justifying the development of a regional LLWW classification for the Southern Rockies1. First, and most straightforward, there are no marine or tidal systems within the Southern Rockies Landscape, allowing for a more streamlined system. Second, the dramatic elevation gradient of the landscape, from alpine systems above the development of any stream channel network, to lower elevation valleys with broad floodplain development, requires a flexible classification that can be applied across this gradient. Third, the hydrology of our watersheds are snowmelt driven, with significant groundwater discharge leading to the formation of wetlands in headwater locations as well as at the base of high elevation slopes. Though many wetlands are geographically contiguous with a riverine system, they are groundwater fed and should thus be classified as “slope” wetlands, though would often be called riverine floodplains in other versions of the LLWW.

1 Though it should be noted that Version 3.0 (Tiner 2014) addresses many of these concerns.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 1 The dependence on snow melt also creates strong season fluctuations in the water table of wetlands and the flow of channels. Many ephemeral or intermittent channels flow in the spring due to snow melt or immediately following late summer storms. Wetlands can be formed within these otherwise dry channels, but do not have an obvious code in the national LLWW key. Fourth, the role of irrigation on wetlands across the west is dramatically different than in other parts of the US. Because of the regional aridity, agriculture largely depends on the diversion of streams or rivers for the delivery of irrigation water to otherwise dry land. The application of irrigation water often results in the incidental creation of wetland ecosystems where previously there existed dry prairie. This novel type of wetland does not lend itself to easy placement within existing classifications.

Notable Differences from LLWW Version 3.0 (Tiner 2014)

The publication of LLWW Version 3.0 addressed many of the concerns outlined above regarding wetland types across the west. As a result of this, Version 3.0 is a more complex classification prone to significant subjectivity between users. We generally follow all the changes suggested in Version 3.0 from the previous iterations, particularly including the recognition of slope wetlands in settings not seen in the east, the emphasis on surface water flow for the coding of Through flow wetlands, the use of Vertical Flow (rather than isolated) for geographically isolated wetlands where the direction of water discharge is downward into the soil, as well as the addition of a landscape position to ponds, lakes, and reservoirs.

The primary difference between the Southern Rockies key, and that described in Tiner (2014) is the specification of landforms and flow paths that only occur with specific landscape positions. This involved, at times, a simplification of the key described by Tiner (2014), as well as the creation of keys specific to each landscape position. This was done in an effort to standardize the use of the keys and to decrease the number of potential code combinations. (example: the Southern Rockies LLWW key does not allow for the coding of a Terrene Fringe wetland, as fringe wetlands should always be either lentic of lotic).

The other notable difference from LLWW Version 3.0 is the collapse of Lotic River and Lotic Stream into one Lotic code. Though we agree there are real ecological and functional differences between streams and rivers, the specific line where a stream becomes a river is highly subjective and, consequently, does not allow for the level of precision needed to meaningfully distinguish between functions.

SOUTHERN ROCKIES LLWW CODING SYSTEM

The classification system for the Southern Rockies LLWW will largely follow the classification laid out in Tiner (2014). Wetlands will be attributed with three main categories: Landscape Position (Table 1), Land form (Table 2), and Water Flow Path (Table 3), with some additional modifier attributes to further describe them. Waterbodies will be attributed with Waterbody Type (Table 4), Landscape Position (Table 1), and Water Flow Path (Table 3), along with some addition modifier attributes to describe them.

Landscape Code Interpretation

Wetlands along a river or stream, or waterbodies within a Lotic River or Stream LR river/stream network. Lentic LE Wetlands in or along a lake or reservoir Wetlands and waterbodies not connected to rivers, streams, or Terrene TE lakes, OR wetlands and waterbodies connected to these features but acting as a source for them

Table 2. LLWW Landform codes and interpretation.

Landform Code Interpretation

Basin BA Wetland exists in a distinct depression Wetland occurs within the banks of a river or stream, or along the shores Fringe FR of a pond or lake Island IS Wetland forms an island within a river, stream, lake, or reservoir Floodplain FP Wetland occurs on a floodplain Slope SL Wetlands occur on a noticeable slope

Table 3. LLWW Water Flow Path codes and interpretation.

Water Flow Path Code Interpretation

Wetland or waterbody receives water from a wetland or waterbody at a Inflow IN higher elevation, but has no observable outflow to a wetland or waterbody at lower elevations Wetland or waterbody discharges water to a wetland or waterbody at a Outflow OU lower elevation, but has no observable inflow from a wetland or waterbody at higher elevations Wetland or waterbody receives water from another wetland or Through flow TH waterbody, and delivers water to another wetland or waterbody at a lower elevation Wetland or waterbody has no inflow from a wetland or waterbody nor Vertical Flow VF delivers water to a wetland or waterbody at a lower elevation. Wetland is geographically isolated Bidirectional BI Water levels fluctuate due to lake influences

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 3 Table 4. LLWW Waterbody codes and interpretation.

Waterbody Code Interpretation Type River/Stream RV Linear features with flowing water when water is present Lake LK Large basin of standing water >20 acres Pond PD Small basin of standing water <20 acres

Coding for Wetlands

Wetlands are attributed with a Landscape Position, Landform, and Water Flow Path at a minimum (Table 5). Lotic wetlands are further described with their Strahler Stream Order, and all wetlands can potentially have some modifier attributes included. Because the total number of possible attribute combinations in the classification is more than what actually exists on the landscape, the Southern Rockies LLWW Classification defines the specific landforms and flow paths that are available for each Landscape Position.

Table 5. LLWW Classification for Wetlands

Wetland = Landscape + Stream Order (LO only) + Landform + Flow path + Modifier Landscape Stream Order Landform Flow path Modifier Position (Lotic Only) Headwaters (hw) Fringe (FR) Bidirectional (BI) Beaver (b) Lentic Island (IS) Through flow (TH) Excavated (x) Impounded (h) Headwaters (hw) Beaver (b) Excavated (x) Fringe (FR) Impounded (h) Island (IS) Though flow (TH) Farmed (f) Lotic Strahler Order Basin (BA) Drained (d) Inflow (IN)* Floodplain (FP) Intermittent (int) Slope (SL)* Unconfined Valley (uv) Intentionally Irrigated (ii) Unintentionally Irrigated (ui) Pond Fringe (pd) Headwaters (hw) Beaver (b) Vertical Flow (VF) Excavated (x) Slope (SL) Inflow (IN) Impounded (h) Terrene (TE) Basin (BA) Outflow (OU) Farmed (f) Through flow (TH) Drained (d) Pond Fringe (pd) Peat Accumulating (pt) * Lotic Slope and Lotic Inflow are only used for wetlands created from irrigation

4 Colorado Natural Heritage Program © 2015 Lentic Wetlands Lentic wetlands are systems that exist because of an adjacent lake or reservoir. The only two landforms available for Lentic wetlands are a fringe and an island. Fringe wetlands will be on the outer perimeter of a lake, while islands will be completely surrounded by the lake. Because lentic wetland hydrology is a function of the varying surface water elevation within the lake, most lentic wetlands will have a flow path of “Bidirectional”, consistent with the rising and lowering of lake levels. Lentic wetlands located where a river bisects the wetland entering the lake are given the flow path of “Through flow” to specifically identify its location at the entrance to the lake.

The boundary between Lentic and Lotic wetlands at the entrance to the lake can be generally identified as the location where the backup of water from the lake influences, and creates, the wetland (Figure 8).

Lotic Wetlands Lotic wetlands associated with a stream or river and exist because of the adjacent body of moving water. These wetlands can be small wetlands adjacent to smaller streams, or large alluvial floodplains adjacent to large rivers. Lotic wetlands are further attributed with the Strahler Order of the adjacent stream or river. This can easily be done, though manually, within GIS by finding the nearest NHD flow line. If a wetland is described as Lotic but is not near a flow line, it is generally because it is a high elevation wetland where no flow line was created. These can be given the stream order of “1”. Lotic wetland landforms can be fringes, islands, floodplains, basins, or slopes. Fringe and island wetlands are located within the channel banks (Figure 1), often the result of a sand bar formation along the edges of the river (fringe) or in the middle of the channel (island). Floodplain wetlands encompass the broadest type of lotic wetland and are used for all wetlands adjacent to, but outside of, the banks of a river or stream (Figure 2).

Different from the national key, lotic basins are only used to described fully vegetated sections of a channel. This is generally used for wetlands within intermittent and ephemeral channels that infrequently have flowing water (Figure 3), as well as channels with slow moving water, such as a slough (Figure 4). The slope landform is only used for Lotic landscape positions to describe wetlands that are formed as the result of irrigation water delivery. The wetland can be formed either from the intentional delivery to a sloping meadow (Figure 5), or the leakage of irrigation water from irrigation canals resulting in the formation of wetlands on slopes or in dry gulleys (Figure 6). All naturally occurring Lotic wetlands are given the flow path of “Through flow”, except irrigated wetlands which can also have a flow path of “Inflow.”

Terrene Wetlands Terrene wetlands are not formed as a result of a waterbody (river, stream, lake, or reservoir). Terrene wetlands can have the landform of slope or basin, and the flow path of “Inflow”, “Outflow”, “Through flow”, or “Vertical Flow”.

Flow Paths Flow paths include Bidirectional, Through flow, Inflow, Outflow, and Vertical Flow. To accurately attribute flow paths, it is important to know how water actually moves through the system. In

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 5 theory, this would entail only looking at the mapping. Unfortunately, many features on the landscape are often not mapped because they are difficult to detect or smaller than the minimum mapping unit. This is particularly true in high elevations, where river channels are thin and run under a thick canopy of trees. It is important to use other data sources to effectively attribute Flow Paths. USGS Topo Maps and NHD flow lines should be used to identify if a wetland is truly isolated, or if it is along a perennial flow path that may not have been mapped.

“Vertical Flow” is used to describe geographically isolated wetlands that have water flowing into them from overland flow or groundwater discharge, and that do not have an outflow to any other wetland or waterbody. Water generally leaves the wetland through the ground. In many places, few wetlands exist in isolation outside of a drainage network. Though theoretically connected to wetlands and waterbodies lower down the drainage network, if a wetland is located in an otherwise dry portion of the network (dry channel above and below), where the channel likely remains dry except immediately following precipitation events, the wetland is considered geographically isolated for this classification.

Modifiers Available modifiers for wetlands include:

• excavated • impounded • drained • farmed • beaver influenced • headwaters • unconfined valley • associated with an ephemeral channel • associated with a pond • intentional delivery of irrigation water • unintentional delivery of irrigation water.

All of these are attributed manually, except the designation of unconfined valleys which uses the Valley Confinement Algorithm (VCA) developed by the USGS to identify unconfined valleys (Nagel, et al., 2014). All wetlands coincident with the polygons created by the VCA are attributed with the unconfined valley modifier. As wetland polygons are often attributed first with their NWI attributes, the attribution of excavated, impounded, and beaver influenced is the same in both classifications and can be automated.

Consistent with Version 3.0 of the LLWW (Tiner 2014), along with a waterbody code and a water flow path, ponds, lakes, and reservoirs also receive a Landscape Position (Table 6).

Table 6. LLWWClassification for Waterbodies

Waterbody = Type + Landscape (LK/PD only) + Flow path + Modifier Waterbody Landscape Flow path Modifier Type Position Headwaters (hw) Lake (LK) Vertical Flow (VF) Beaver (b) Lentic (LE) Inflow (IN) Excavated (x) Lotic (LO) Outflow (OU) Impounded (h) Terrene (TE) Pond (PD) Through flow (TH) Intentionally Irrigated (ii) Unintentionally Irrigated (ui) Headwaters (hw) Through flow (TH) Beaver (b) River (RV) Outflow (OU) Excavated (x) Inflow* Impounded (h) Intermittent (int) * River Inflow is generally used to describe excavated irrigation canals

Lakes and Ponds The attribution of lakes and ponds is the same as in the NWI Cowardin classification. Should the polygons be attributed with the Cowardin code first, all NWI polygons having the code of L1 or L2 should be called a lake, and all codes with a PUB or PAB should be called a pond. Lakes and ponds are further attributed with their landscape position, which will generally be either “Lotic” or “Terrene”. Terrene lakes or ponds include those in the upper most reaches of a watershed, with no channel, lake, or pond above them, but leading into a river network below (Figure 10), as well as geographically isolated lakes and ponds (Figure 11and Figure 12). Lotic lakes and ponds are those that are part of a river network, with flowing channels both above and below them (Figure 13). It is also possible, though generally not the case in Colorado, to have Lakes and Ponds in a Lentic position. This would include smaller lakes or ponds that are located within the confines or a larger lake system.

The flow path options of lakes and ponds include “Vertical Flow”, “Inflow”, “Outflow”, and “Through flow”. Lakes and Ponds that are geographically isolated are attributed with “Vertical Flow” to identify water entry and exit generally from groundwater movement, with no connection a perennial channel or other mapped waterbody (Figure 11and Figure 12). Inflow describes lakes and ponds that receive water, but have no outflow. These are often man made features on the landscape. Outflow lakes and ponds are generally situated at high elevations where water pools in a depression, and then outflows to a channel (Figure 10). Through flow systems have water entering and exiting them from another waterbody (Figure 13).

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 7 Rivers The original LLWW versions separate rivers from streams based on USGS topo maps, where streams are identified as a line and rivers as a polygon. While we do not disagree that ecological functions between rivers and streams are different, we believe there is no meaningful ecological distinction between lines and polygons features on a USGS topo map. We have therefor combined rivers and streams, and call everything a river. Generally, rivers are designated with a “Through flow” attribute. The few exceptions to this are river segments originating where the channel network begins (outflow), or where water from a river is diverted into an excavated irrigation canal or lateral (inflow).

Modifiers The available modifiers for waterbodies include: • excavated • impounded • beaver influenced • headwaters • intermittent channel.

For any wetland, whether studied in the field or drawn in a GIS, the first task is to identify the Landscape Position of the wetland. This is generally accomplished by identifying the water source for the wetland. If water comes from a river or stream, the landscape position is Lotic. If water comes from a lake, the landscape position is Lentic. If it doesn’t come from either of these, the wetland is classified as Terrene. Each of the three landscape positions have their own path within the key, so simply follow the keys directions to identify the landform and flow path of the wetland.

Examples of LLWW Attributed Wetlands

This section is meant to provide examples and clarification of common attributes used, as well as some tricky examples.

Lotic Fringe/Lotic Island Lotic fringe wetlands and lotic island wetlands both exist within the banks of a channel. They can be vegetated (NWI code PSS) or unvegetated (NWI code R3US) and are commonly known as point bars, sand bars, and mid-channel bars (Figure 1).

Figure 1. Lotic Fringe and Lotic Island wetlands within the banks of the Arkansas River.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 9 Lotic Floodplain Lotic Floodplain wetlands are generally the most intuitive to identify, but the Lotic Floodplain attribute describes a wider variety of wetlands in the Southern Rockies LLWW classification than in the national version. We found there to be some redundancies and mixed messages within the floodplain group. To simplify this key, if a wetland is adjacent to a stream or a river, and is hydrologically connected to, and specifically exists because of that stream or river, it is called a floodplain (Figure 1).

Figure 2. Lotic Floodplain wetlands (outlined in light blue). Lotic Floodplain wetlands are formed by the overbank flooding action of rivers or streams. Note: Location next to a channel does not automatically infer Lotic or Floodplain. Wetlands adjacent to rivers or streams but fed by groundwater discharge should be classified as Terrene.

Lotic Basin Lotic Basin defines a different type of wetland than the national level LLWW classification. Within the Southern Rockies LLWW, Lotic Basins represent fully vegetated channels. This is often an ephemeral or intermittent channel that only has flowing water following precipitation events (Figure 2). Topographic variation within the channel holds enough water to create a vegetated wetland when flowing water is absent. Another example of a Lotic Basin could be a warm water slough along the plains. These systems form channels of very slow moving water that are more similar to marshes than they are to other lotic systems (Figure 3).

Figure 3. Lotic Basin wetland as a fully vegetated channel with no flowing water. Wetland is formed inside a channel where overland flow from precipitation events concentrates, forming the wetland in the channel bottom.

Figure 4. Lotic Basin wetland as a channel with very slow moving water, leading to the formation of wetland vegetation throughout the entire channel. The water is moving and therefor Lotic, but the wetland is formed within the channel rather than on a floodplain.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 11 Lotic Slope Lotic slopes are an artificially, though generally unintentionally, created wetland on the landscape. Water is diverted from rivers and streams into canals that deliver water to fields. Enough water can sometimes be applied to create a wet meadow (Figure 4). These systems are generally on sloping lands, but the water is delivered through flowing canals. Without irrigation, these areas would not be wetlands. Another type of Lotic Slope my occur from the seepage of water from an irrigation canal or the overland flow of water from an irrigated field (Figure 5).

Figure 5. Lotic slopes are fields irrigated with enough water to create a sloping wetland. Wetlands here are incidental to the irrigation process, but water is delivered intentionally in this case. The wetlands in the lower half of the image are Lotic Slope Through flow. The wetland in the upper right is a Lotic Slope Inflow.

Figure 6. Lotic Slope wetlands can also be the result of unintentional delivery of irrigation water. In this case, wetlands are due to seepage from irrigation canals. These can be classified as Lotic Slope Inflow, or Lotic Slope Through flow depending on how water moves through the system.

12 Colorado Natural Heritage Program © 2015 Terrene Slope Outflow (headwater wetlands discharging to stream) Terrene Slope Outflow wetlands are formed as the results of groundwater discharge to a slope wetland, which then flows into the channel. These wetlands often exist where channel formation begins, but can also exist on the sides of existing channels where slope breaks lead to groundwater discharge. In the example below, the channel forms within the wetland in the lower left, and bisects the other two wetlands in the upper right (Figure 6). Though all three wetlands are contiguous with the channel, none of them are created from the channel. Water flows from each wetland into the channel.

Figure 7. Terrene Slope Outflow headwater wetlands.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 13 Terrene Basin Terrene Basin are not connected to a waterbody, and are formed due to a depression in the landscape that collects enough water, either overland flow or groundwater discharge, to create a wetland (Figure 7).

Figure 8. Terrene Basin wetlands. Water flow path in this instance is vertical flow.

14 Colorado Natural Heritage Program © 2015 Lentic Fringe Lentic fringe wetlands are generally easy to identify, as they exist along the margins of Lakes and Reservoirs. The difficult decision is often when a river with an expansive floodplain joins a river or reservoir. Where the lotic wetlands become lentic wetlands can generally be thought of as where the influences of the backed up water no longer drive the hydrology in the wetland. In other words, if the lake or reservoir were removed, any wetland that no longer would exist should be classified as Lentic. Wetlands on the outside of lakes or reservoirs most commonly have the bidirectional flow path descriptor, except when the incoming river bisects the wetland. These should be given the flow path attribute of Through flow.

Figure 9. Lentic Fringe Wetlands. In cases such as this where a river is entering the lake or reservoir, lentic wetlands are separated from Lotic wetlands based on where the lake’s influence likely reaches. Though subjective, asking which wetlands would disappear if the lake were removed is a good way to delineate lentic from lotic.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 15 Examples of LLWW Attributed Waterbodies

Terrene Outflow Lake High elevation lakes that empty into the start of a river network are classified as Terrene Outflow. Similar to slope wetlands are the headwaters of a river, if the lake is not fed by a channel above it, is is classified as Terrene.

Figure 10. Terrene Outflow Lake. Lakes with no waterbodies above them that drain into a river are classified as Terrene Outflow.

16 Colorado Natural Heritage Program © 2015 Terrene Vertical Flow Pond Ponds (or lakes) that are geographically isolated have a Terrene landscape position. Many such ponds are connected to a physical channel, though the channel is dry for most times of the year. In high elevation cirques, many ponds and lakes are largely isolated as there is not enough water flowing into them for them to empty into the channel (Figure 11). In arid regions, many dry channels formed in precipitation events have impounded depressions meant to capture precipitation runoff. Though existing within a drainage, they are otherwise hydrologically isolated from other waterbodies and wetlands, and should be given the Vertical Flow flow path (Figure 12).

Figure 11. Terrene Vertical Flow Pond. Though a channel exists where water may flow out of the pond at very wet

Figure 12. Terrene Vertical Flow pond as impounded ponds in dry channels.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 17 Lotic Through flow Lake Although some lakes may be in the headwater portions of a river network, if they are fed by a channel they are classified as Lotic. If there is both an inflowing channel and an outflowing channel, the lake is Lotic Through flow (Figure 13).

Figure 13. Lotic Through flow Lake

Key A: Wetland and Waterbody Landscape Position

1. Wetland is connected to a waterbody (lake, reservoir, river or stream) ...... 2 1. Wetland is not connected to a waterbody ...... Terrene (TE) Go to Key B-1 for Terrene Landforms and C-1 for Terrene Flow Paths

2. Wetland is located in or along a lake or reservoir (permanent waterbody where standing water is typically deeper than 6.6 feet or larger than 20 acres), including streamside wetlands in a lake basin ...... 3 2. Wetland is located along a river or stream (including in-stream ponds), within its banks, or on its floodplain ...... 4

3. Wetland is located in or along a lake or reservoir but does not receive water from it, instead discharging water into the lake or reservoir ...... Terrene (TE) Go to Key B-1 for Terrene Landforms and C-1 for Terrene Flow Paths 3. Wetland is located in or along a lake or reservoir and is hydrologically controlled by the waterbody ...... Lentic (LE) Go to Key B-2 for Lentic Landforms and C-2 for Lentic Flow Paths

Note: Lentic wetlands consist of all wetlands in a lake basin (i.e., the depression containing the lake), including lakeside wetlands intersected by streams emptying into the lake. The upstream limit of lentic wetlands is defined by the upstream influence of the lake, usually approximated by the limits of the lake basin.

4. Wetland is adjacent to a river or stream, but discharges water into the river; wetland is likely controlled more by groundwater discharge than by river processes ...... Terrene (TE) Go to Key B-1 for Terrene Landforms and C-1 for Terrene Flow Paths 4. Wetland is located in a river or stream, within its banks, or on its active floodplain and is hydrologically controlled by the river or stream ...... Lotic (LO) Go to Key B-3 for Lotic Landforms and C-3 for Lotic Flow Paths

Note: Immediately following the Lotic code, wetlands should be further attributed with a number that directly corresponds to the Strahler Order of the associated river or stream.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 19 Key B: Wetland Landforms

Key B-1: Terrene Landforms Wetland occurs on a slope and hydrology is largely influenced by groundwater discharge to the surface or surface runoff accumulation into a dry gulley ...... Slope (SL) Wetland exists in a distinct depression that backs up or slows down water ...... Basin (BA)

Key B-2: Lentic Landforms Wetland occurs on an island within a lake or reservoir ...... Island (IS) Wetland occurs along the shores of a lake or reservoir ...... Fringe (FR)

Key B-3: Lotic Landforms 1. Wetland occurs within the banks of a river or stream ...... 2 1. Wetland does not occur within the banks of a river or stream ...... 4

2. Wetland exists as a fully vegetated section of channel ...... Basin (BA) 2. Wetland occurs along the banks or on an island within a river or stream ...... 3

3. Wetland occurs along the banks of a river or stream ...... Fringe (FR) 3. Wetland occurs on an island within a river or stream ...... Island (IS)

4. Wetland occurs on the alluvial floodplain of a river ...... Floodplain 4. Wetland is formed, either intentionally or unintentionally, from the delivery of irrigation water or the seeping of water from an irrigation canal ...... Slope

Key C-1: Terrene Wetland Flow Paths 1. Wetland receives surface water from a waterbody or wetland at a higher elevation and surface water passes through it to a waterbody or wetland at a lower elevation; a flow through system ...... Through flow (TH) 1. Water does not pass through the wetland to other wetlands or waters ...... 2

2. There is no observed or known perennial surface water inflow from a stream or wetland and no observed or known perennial outflow of surface water to other wetlands or waters; wetland exists in geographic isolation ...... Vertical Flow (VF) 2. Waterbody or wetland is not hydrologically or geographically isolated ...... 3

3. Wetland receives surface water inflow from a wetland or waterbody at a higher elevation but no observable surface water outlet exists ...... Inflow (IN) 3. Wetland does not receive surface water inflow from a wetland or waterbody at a higher elevation but water is discharged from the wetland to a waterbody, or other wetland at a lower elevation ...... Outflow (OU)

Key C-2: Lentic Flow Paths Wetland is bisected or adjacent to a stream or river entering the lake or reservoir, though water levels in the wetland are primarily controlled by lake processes ...... Through flow (TH) Water levels fluctuate due to lake influences or variable water levels ...... Bidirectional (BI)

Key C-3: Lotic Flow Paths 1. Wetland landscape position is lotic and is not the result of irrigation ...... Through flow (TH) 1. Wetland landscape position is lotic and is the result of irrigation ...... 2

2. Water enters the wetland from an irrigation canal and exits the wetland to another wetland or excavated channel ...... Through flow (TH) 2. Water enters the wetland from an irrigation canal and does not exit the wetland to another wetland or excavated channel ...... Inflow (IN)

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 21 Codes for wetland modifiers (apply at end of code for given wetland) Terrene Modifiers x Modified by excavation h Modified by dam, dike, or impoundment d Modified by a ditch or has been partially drained f Wetland has been actively farmed b Modified by a beaver dam hw Wetlands that exist above an a priori determined elevation, above which the wetlands perform disproportionate water quality and quantity benefits to the watershed pd Wetland is formed along the fringe of a pond pt Wetland is a peat accumulating system (fen)

Lentic Modifiers x Modified by excavation h Modified by dam, dike, or impoundment b Modified by a beaver dam hw Wetlands that exist above an a priori determined elevation, above which the wetlands perform disproportionate water quality and quantity benefits to the watershed

Lotic Modifiers x Modified by excavation h Modified by dam, dike, or impoundment d Modified by a ditch or has been partially drained f Wetland has been actively farmed b Modified by a beaver dam hw Wetlands that exist above an a priori determined elevation, above which the wetlands perform disproportionate water quality and quantity benefits to the watershed ii Irrigation water is intentionally delivered to a field resulting in the creation of a wetland, typically forming a wet meadow ui Water is unintentionally delivered to a field, often the result of leakage from an irrigation ditch or canal, resulting in the creation of a wetland, typically forming a wet meadow uv Wetland is located within an unconfined valley, as identified by the USGS Valley Confinement Algorithm. Generally applied to lotic wetlands, though at high elevations some Terrene Slope wetlands may get included int Lotic wetland is associated with an intermittent or ephemeral stream pd Wetland is formed along the fringe of a pond

Key D-1: Waterbody Types 1. Waterbody is predominantly standing water ...... 2 1. Water, when present, is predominantly flowing ...... River (RV)

2. Waterbody is permanently flooded and deep (> 6.6 feet) ...... Lake (LK) Go to Key D-2 for Waterbody Landforms and D-3 for Waterbody Flow Paths 2. Waterbody is shallow (< 6.6 feet) ...... Pond (PD) Go to Key D-2 for Waterbody Landforms and D-3 for Waterbody Flow Paths

Key D-2: Waterbody Landscape Position (for lakes, reservoirs and ponds only) 1. Lake or pond is the source of a river or stream or is geographically isolated ...... Terrene (TE) 1. Lake or pond is connected to another waterbody (lake, reservoir, river or stream) but is not the water source of them ...... 2

2. Pond is located in or along another lake or reservoir ...... Lentic (LE) 2. Lake or pond is located in a river or stream network, but is not the river’s source ...... Lotic (LO) Note: Immediately following the Lotic code, waterbodies should be further attributed with a number that directly corresponds to the Strahler Order of the associated river or stream.

Key D-3: Waterbody Flow Paths 1. Waterbody receives surface water from a waterbody at a higher elevation and surface water passes through it to another waterbody at a lower elevation ...... Through flow (TH) 1. Water does not pass through the waterbody to other waters ...... 2

2. No observable perennial surface water connection to other waters exist; sources of water include precipitation, local runoff or groundwater discharge ...... Vertical Flow (VF) 2. Waterbody is not hydrologically or geographically isolated ...... 3

3. Water flows into the waterbody via a river, stream, or canal with no observable surface water outflow ...... Inflow (IN) 3. Water flows out of the waterbody via a river, stream, with no observable surface water inflow Outflow (OU)

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 23 Waterbody Modifiers

Lake and Pond Modifiers x Modified by excavation h Modified by dam, dike, or impoundment d Modified by a ditch or has been partially drained b Modified by a beaver dam hw Waterbodies that exist above an a priori determined elevation, above which the wetlands perform disproportionate water quality and quantity benefits to the watershed ii Intentional delivery of water to a waterbody, typically a pond or reservoir ui Water is unintentionally delivered to a waterbody, often as ditch or canal seepage being collected in a small pond in a gulley

River Modifiers x Modified by excavation h Modified by dam, dike, or impoundment b Modified by a beaver dam hw Waterbodies that exist above an a priori determined elevation, above which the wetlands perform disproportionate water quality and quantity benefits to the watershed int intermittent or ephemeral stream

Brinson, M.M. 1993. A Hydrogeomorphic Classification for Wetlands. U.S. Army Corps of Engineers, Washington, DC. Wetlands Research Program, Technical Report WRP-DE-4.

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.

Tiner, R.W. 2003. Keys to Waterbody Type and Hydrogeomorphic-Type Wetland Descriptors for U.S. Waters and Wetlands. U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA.

Tiner, R.W. 2014. Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors. Version 3.0. U.S. Fish and Wildlife Service, National Wetlands Inventory Program, Northeast Region, Hadley, MA.

Southern Rockies Classification for Landscape Level Wetland Functional Assessments 25