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Ecological site R028AY014UT

Semiwet Fresh Streambank

Last updated: 5/02/2025
Accessed: 10/20/2025

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

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Figure 1. Mapped extent

Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.

MLRA notes

Major Land Resource Area (MLRA): 028A–Ancient Lake Bonneville

MLRA 28A occurs in Utah (82 percent), Nevada (16 percent), and Idaho (2 percent). It encompasses approximately 36,775 square miles (95,246 square kilometers). A large area west and southwest of Great Salt Lake is a salty playa. This area is the farthest eastern extent of the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. It is an area of nearly level basins between widely separated mountain ranges trending north to south. The basins are bordered by long, gently sloping alluvial fans. The mountains are uplifted fault blocks with steep side slopes. Most of the valleys are closed basins containing sinks or playa lakes. Elevation ranges from 3,950 to 6,560 feet (1,204 to 2000 meters) in the basins and from 6,560 to 11,150 feet (1996 to 3398 meters) in the mountains. Much of the MLRA has alluvial valley fill and playa lakebed deposits at the surface from pluvial Lake Bonneville, which dominated this MLRA 13,000 years ago. A level line of remnant lake terraces on some mountain slopes indicates the former extent of this glacial lake. The Great Salt Lake is what remains of the pluvial lake.

Mountains in the interior of this MLRA consist of tilted blocks of marine sediments from Cambrian to Mississippian age with scattered outcrops of Tertiary continental sediments and volcanic rocks. The average annual precipitation is 5 to 12 inches (13 to 30 cm) in the valleys and ranges up to 49 inches (124 cm) in the mountains. Most of the rainfall in the southern LRU occurs as high-intensity, convective thunderstorms during the growing season (April through September). The driest period is from midsummer to early autumn in the northern LRU. Precipitation in winter typically occurs as snow. The average annual temperature is 39 to 53 °F (4 to 12 °C). The freeze-free period averages 165 days and ranges from 110 to 215 days, decreasing in length with increasing elevation. The dominant soil orders in this MLRA are Aridisols, Entisols, and Mollisols. Soils are dominantly in the mesic or frigid soil temperature regime, aridic or xeric soil moisture regime, and mixed mineralogy. The soils are generally well drained, loamy or loamy-skeletal, and very deep.

LRU notes

The Salt Desert/Wetland LRU consists of all the run-in ecological sites. Run-in sites occur in landform positions that receive additional moisture either through overland flow or subsurface water flow. Typical landforms are basin floors, lake plains, low lake terraces, depressional areas, drainageways, and flood plains. Sites within this LRU typically have water table depths of less than 60 inches (152 cm). Wetland plants, pickleweed (Salicornia sp.) and/or greasewood (Sarcorbatus vermiculatus) are dominant in the plant communities.

Ecological site concept

The Semiwet Fresh Streambank site occurs on flood plains and floodplain steps on slopes less than 4 percent. It can be found at elevations between 4,500 to 5,900 feet. The water table is typically between 18 and 72 inches below the soil surface. The Semiwet Fresh Streambank site is not directly adjacent to to the stream, but on the fluvial surface further out from the channel. The Semiwet Fresh Streambank will have a deeper water table than the Wet Fresh Streambank site and will not be flooded regularly. Flooding occurs occasionally to rarely and briefly to very briefly. The dominant plants are Fremont cottonwood (Populus fremontii), coyote willow (Salix exigua), and a herbaceous understory. The plant community will typically only develop under a certain set of circumstances. Cottonwoods need bare, moist soil to establish. The plant community has to be positioned far enough away from the stream channel to not experience frequent flooding but close enough to have a water table within 60 inches of the soil surface during the growing season.

Associated sites

R028AY022UT	Wet Fresh Streambank This site will be found closer to the stream channel and is typically wetter.
R028AY020UT	Wet Fresh Meadow This site may be found in low lying areas within the flood plain or floodplain-step
R028AY012UT	Semiwet Fresh Meadow This site may be found in low lying areas within the flood plain or floodplain-step.

R028AY022UT

Wet Fresh Streambank

This site will be found closer to the stream channel and is typically wetter.

R028AY020UT

Wet Fresh Meadow

This site may be found in low lying areas within the flood plain or floodplain-step

R028AY012UT

Semiwet Fresh Meadow

This site may be found in low lying areas within the flood plain or floodplain-step.

Similar sites

R028AY022UT	Wet Fresh Streambank This site will have more obligate wetland species in the plant community and will be found closer to the stream channel.

R028AY022UT

Wet Fresh Streambank

This site will have more obligate wetland species in the plant community and will be found closer to the stream channel.

Table 1. Dominant plant species

Tree	(1) Populus fremontii
Shrub	(1) Salix exigua
Herbaceous	Not specified

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Physiographic features

The Semiwet Fresh Streambank site occurs on gently sloping flood plains, alluvial fans, and flood-plain steps in canyons and small valley bottoms. It is found at elevations between 4,500 and 5,900 feet on slopes no greater than 4 percent in most cases. Brief flooding events may occur on this site occasionally, but ponding is not an issue. The water table fluctuates throughout the year, but stays mostly between 18 and 72 inches from the soil surface.

Table 2. Representative physiographic features

Landforms	(1) Flood plain (2) Alluvial fan (3) Flood-plain step
Flooding duration	Very brief (4 to 48 hours) to brief (2 to 7 days)
Flooding frequency	None to occasional
Ponding frequency	None
Elevation	4,500 – 5,490 ft
Slope	4%
Water table depth	18 – 72 in
Aspect	Aspect is not a significant factor

Climatic features

The climate is characterized by cold, snowy winters and warm dry summers. Annual precipitation typically ranges between 12 and 20 inches, though a high water table is the most important water resource for plant growth. The water table can be elevated as early as March and as late as August in some areas. June through September are the driest months, accounting for only 20 percent of the annual precipitation. October through May are the wet months, and account for the other 80 percent of the annual precipitation.

Table 3. Representative climatic features

Frost-free period (characteristic range)	85-128 days
Freeze-free period (characteristic range)	119-165 days
Precipitation total (characteristic range)	12-19 in
Frost-free period (actual range)	74-139 days
Freeze-free period (actual range)	107-177 days
Precipitation total (actual range)	10-21 in
Frost-free period (average)	107 days
Freeze-free period (average)	142 days
Precipitation total (average)	16 in

Characteristic range

Actual range

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Figure 2. Monthly precipitation range

Characteristic range

Actual range

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Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 4. Monthly maximum temperature range

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Figure 5. Monthly average minimum and maximum temperature

Figure 6. Annual precipitation pattern

Figure 7. Annual average temperature pattern

Climate stations used

(1) SPANISH FORK PWR HOUSE [USC00428119], Spanish Fork, UT
(2) CIRCLEVILLE [USC00421432], Kingston, UT

Soil features

The soils are deep, gravelly sandy loams that formed in alluvium derived from mixed parent materials. Rock fragments are abundant throughout the profile and are usually present on the soil surface. Textures are variable throughout the profile and are often highly stratified. These soils are poorly-drained to well-drained and have moderately rapid to very rapid permeability. The soils are often highly calcareous and have pH ranging from 7.4 to 8.4. Available water-holding capacity ranges from 1 to 3 inches of water in the upper 40 inches of soil. The soil moisture regime is aquic and the soil temperature regime is mesic.

This site is found in the Utah County Soil Survey Area (UT621), and is correlated to the Provo (Pw) and Steed (Sd, Se) soil components. It is also found in surveys UT628 and UT629 on Numana (174, 112, 142, 177) and Provo (Px, 103) soil components.

Table 4. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Gravelly sandy loam (2) Gravelly fine sandy loam (3) Sand
Family particle size	(1) Sandy
Drainage class	Poorly drained to well drained
Permeability class	Moderately rapid to very rapid
Soil depth	60 in
Surface fragment cover <=3"	5 – 27%
Surface fragment cover >3"	5%
Available water capacity (0-40in)	0.9 – 2.7 in
Calcium carbonate equivalent (0-40in)	1 – 40%
Electrical conductivity (0-40in)	8 mmhos/cm
Sodium adsorption ratio (0-40in)	5
Soil reaction (1:1 water) (0-40in)	7.4 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	35 – 39%
Subsurface fragment volume >3" (Depth not specified)	6 – 30%

Ecological dynamics

Semiwet Fresh Streambank is found on the flood plains and floodplain-steps of stream channels originating in the Wasatch Mountains. The dominant species in reference condition are cottonwood (Fremont or Narrowleaf), coyote willow, and grasses and sedges. Narrowleaf cottonwood will be found closer to the foothills coming out from the mountain canyons, while Fremont Cottonwood will typically be found on the broader floodplains in the valley bottoms. Cottonwoods will typically only survive to mature trees on the slightly elevated fluvial surfaces of flood plains and floodplain-steps because those landforms are not flooded frequently while the soil remains wet enough for germination of cottonwood seedlings. Coyote willow is a rhizomatous shrub that can grow in very wet conditions and the stems can withstand seasonal floodwaters and inundation. The typical understory for this site is unknown and was not documented before disturbance, but was most likely dominated by sedges, rushes, and grasses that are tolerant to wet conditions.

The Semiwet Fresh Streambank site has been altered by farming practices and urbanization. Some portion of water in the streams has been diverted out of many, if not all, of the streams along the Wasatch Front, which will alter the stream and flood plain hydrology, typically creating drier conditions in the flood plains. Channelization of streams in this area also affect the extent and hydrology of this site. Restricting moving water into a channel and not allowing floodwaters to inundate flood plains can reduce appropriate germination sites for cottonwood. Over time cottonwoods will have less recruitment and the trees will eventually leave the site. The Semiwet Fresh Streambank site is also susceptible to Russian olive (Eleagnus angustifolia) and tamarisk (Tamarix sp.) invasion.

State and transition model

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State

SWAPAEH

2. Current Potential State

SWAPAEH

3. Channelized/Degraded State

SWAPAEH

State 1
Reference State

The Reference State concept has two main community phases influenced by time since disturbance (flooding, fire, etc.). Cottonwood seeds will be left behind after a seasonal flood event. The cottonwood seedlings will germinate if the soil conditions are right (moist and bare). These seedlings, if left undisturbed, will mature to trees. Understory plants, like rhizmomatous willow and graminoids are less influenced by seasonal flooding and may remain intact after seasonal flooding. Extreme flooding or fire may remove the tree overstory and the understory, allowing the graminoids and willows to dominate the site until the conditions are appropriate for cottonwood establishment.

Community 1.1
Cottonwood/willow/graminoids

Community Phase 1.1 is dominated by mature cottonwood trees and may have a diverse understory of willows and graminoids. Community Phase 1.1 develops during the time between disturbances. The dominant aspect of the plant community is cottonwood trees, willows, and grasses or grasslike plants. The composition by air-dry weight is approximately 45 percent perennial grasses, 15 percent forbs, and 40 percent shrubs.

Figure 8. Annual production by plant type (representative values) or group (midpoint values)

Table 5. Annual production by plant type

Plant type	Low (lb/acre)	Representative value (lb/acre)	High (lb/acre)
Grass/Grasslike	405	653	900
Shrub/Vine	360	580	800
Forb	135	218	300
Total	900	1451	2000

Table 6. Ground cover

Tree foliar cover	10-15%
Shrub/vine/liana foliar cover	15-30%
Grass/grasslike foliar cover	4-5%
Forb foliar cover	1-5%
Non-vascular plants	0%
Biological crusts	0%
Litter	0%
Surface fragments >0.25" and <=3"	0%
Surface fragments >3"	0%
Bedrock	0%
Water	0%
Bare ground	0%

Table 7. Canopy structure (% cover)

Height Above Ground (ft)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.5	–	–	–	–
>0.5 <= 1	–	–	–	0-10%
>1 <= 2	–	–	0-10%	–
>2 <= 4.5	–	–	–	–
>4.5 <= 13	–	25-35%	–	–
>13 <= 40	10-20%	–	–	–
>40 <= 80	–	–	–	–
>80 <= 120	–	–	–	–
>120	–	–	–	–

Figure 9. Plant community growth curve (percent production by month). UT0141, PNC. Excellent Condition.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	5	15	40	30	5	5	0	0	0	0

Community 1.2
Willows/graminoids

Community Phase 1.2 occurs after a disturbance that removed the tree canopy. This can occur after a fire or large flood.

Pathway 1.1a
Community 1.1 to 1.2

Flooding, fire, or other disturbance that removes the tree canopy.

Pathway 1.2a
Community 1.2 to 1.1

Sufficient time to allow the cottonwood trees to again establish on the site.

State 2
Current Potential State

The Current Potential State occurs after non-native plant species introduction. The species can range from trees, shrubs, to herbaceous. Russian olive, tamarisk, Kentucky bluegrass, and thistles are common non-native plants.

Community 2.1
Native and Non-native trees/shrubs/graminoids

Non-native trees, like Russian olive are present and may dominate the tree canopy. Tamarisk may also occur and take the place of native willows. Kentucky bluegrass is effective at invading wet to semiwet sites and may dominate the understory.

State 3
Channelized/Degraded State

The Channelized/Degraded state is characterized by a adjacent stream that has been channelized. Most seasonal floodwaters remain the in channel and do not inundate the flood plain. This reduces cottonwood recruitment and may reduce soil moisture on the site allowing species that are more tolerant to dry conditions to establish.

Community 3.1
Degraded Community Phase

Plant Community Phase 3.1 may look like a drier ecological site with sagebrush or rabbitbrush. This phase may also be converted to a agricultural field or urban development.

Transition T1A
State 1 to 2

Introduction of non-native species.

Transition T1B
State 1 to 3

Channelization of adjacent stream channel.

Transition T2A
State 2 to 3

Reduced soil moisture and altered hydrology of the site. Urbanization and agriculture uses may be present.

Additional community tables

Table 8. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Tree
1	Trees			0
	boxelder	ACNE2	Acer negundo	0	–
	narrowleaf cottonwood	POAN3	Populus angustifolia	0	–
	Fremont cottonwood	POFR2	Populus fremontii	0	–
Shrub/Vine
2	Primary Shrubs			315–450
	narrowleaf willow	SAEX	Salix exigua	225–300	–
	silver buffaloberry	SHAR	Shepherdia argentea	45–75	–
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	45–75	–
3	Secondary Shrubs			75–150
	Utah serviceberry	AMUT	Amelanchier utahensis	15–45	–
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	15–45	–
	western white clematis	CLLI2	Clematis ligusticifolia	15–45	–
	rubber rabbitbrush	ERNA10	Ericameria nauseosa	15–45	–
	skunkbush sumac	RHTRT	Rhus trilobata var. trilobata	15–45	–
	Woods' rose	ROWO	Rosa woodsii	15–45	–
	coralberry	SYOR	Symphoricarpos orbiculatus	15–45	–
Grass/Grasslike
3	Primary Grasses			465–675
	Kentucky bluegrass	POPR	Poa pratensis	300–375	–
	clustered field sedge	CAPR5	Carex praegracilis	75–150	–
	arctic rush	JUAR2	Juncus arcticus	45–75	–
	western wheatgrass	PASM	Pascopyrum smithii	45–75	–
1	Seconary Grasses			75–150
	creeping bentgrass	AGST2	Agrostis stolonifera	15–45	–
	saltgrass	DISP	Distichlis spicata	15–45	–
	timothy	PHPR3	Phleum pratense	15–45	–
	basin wildrye	LECI4	Leymus cinereus	15–45	–
	squirreltail	ELEL5	Elymus elymoides	15–45	–
Forb
4	Primary Grasses			45–75
	silverweed cinquefoil	ARAN7	Argentina anserina	45–75	–
2	Seconary Forbs			75–150
	white sagebrush	ARLU	Artemisia ludoviciana	15–45	–
	field horsetail	EQAR	Equisetum arvense	15–45	–
	redwool plantain	PLER	Plantago eriopoda	15–45	–
	gooseberryleaf globemallow	SPGR2	Sphaeralcea grossulariifolia	15–45	–
	common dandelion	TAOF	Taraxacum officinale	15–45	–
	strawberry clover	TRFR2	Trifolium fragiferum	15–45	–

Interpretations

Animal community

Semiwet Fresh Streambank is one of Utah’s highest yielding range sites. The plants are predominantly grasses and grasslike plants with a few forbs and practically no shrubs. To control soil erosion and degradation of the plant community, this site may be properly grazed early with animals being removed early to allow key plants to go ungrazed during the last part of the growing season. A stubble height of 4 to 5 inches should be adhered to.

Wildlife using this site include rabbit, coyote, raccoon, owl, bald eagle, and mule deer.

This is a short list of the more common species found. Many other species are present as well and migratory birds are present at times.

Hydrological functions

Soils are grouped mainly into C hydrologic group. They have moderately high runoff potential. When the vegetation is in climax (potential), the hydrologic curves are 75 to 72. Refer to SCS National Engineering Handbook, Section 4, to determine runoff quantities by use of these curves. Where range condition has declined from climax, field investigation is needed to determine hydrologic curve numbers.

Recreational uses

The Semiwet Fresh Streambank site has good values for aesthetics and natural beauty. It has a large number of forbs and shrubs which have flowers in bloom from early spring throughout the summer and into the fall. It has a combination of grasses, forbs, small shrubs, large shrubs, and trees which offer excellent possibilities for screening and high value as camping and picnicking areas. Hunting for upland game birds, cottontail rabbits, elk, and mule deer is good to excellent on this site. Fishing is opportune on streams through this site. Summer homes are a possibility on this site, but detailed on-site investigation should be made to determine feasibility of the soils for septic tanks and sewage disposal facilities when specific location are tentatively planned for summer homes or other building sites. Due to the high water table, sewage disposal is extremely difficult.

Wood products

The tree species, except for cottonwood, do not grow large enough to make them valuable for lumber. Occasionally, cottonwood and rocky mountain juniper have been used for saw timber. No site index determinations have been made to date on these species. Some values exist for fence posts and fuel for fireplaces and campfires. Some species furnish raw material for knick-knacks, or ornamental uses.

Other information

Threatened and endangered species include plants and animals.

Rangeland health reference sheet

Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.

Author(s)/participant(s)
Contact for lead author
Date	05/05/2025
Approved by	Jamin Johanson
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):

Dominant:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Perennial plant reproductive capability:

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Natural ResourcesConservation Service

Ecological site R028AY014UT

Semiwet Fresh Streambank

Last updated: 5/02/2025 Accessed: 10/20/2025

General information

Figure 1. Mapped extent

MLRA notes

LRU notes

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Ecosystem states

State 1 submodel, plant communities

State 2 submodel, plant communities

State 3 submodel, plant communities

Natural Resources
Conservation Service

Last updated: 5/02/2025
Accessed: 10/20/2025