Wetlands

&

Organic Soils

Bellevue & Issaquah

Soils and Land Use

ESRM 311- SEFS 507

Wetlands

• Areas where water covers the soil, or is present

either at or near the surface of the soil all year or

for varying periods of time during the year,

including during the growing season. (US EPA) http://water.epa.gov/type/wetlands/what.cfm

Wetlands • productive and diverse waters that stand between upland

and open water.

• important to water quality, flood storage, and biodiversity

• economists estimate that one acre of wetlands provides

about $10,000 worth of ecosystem services which

include:

• filtering and recharging drinking water,

• preventing flooding,

• protecting our coasts from hurricanes and storms, and

• providing habitat for diverse wildlife populations.

http://www.nwf.org/What-We-Do/Protect-Habitat/Waters/Wetlands-and-Watersheds.aspx 3

4

How wetlands work!!

Delineating Wetlands using:

1) Hydrology

2) Hydrophytic vegetation

3) Hydric soils

5

marsh

type of wetland ecosystem characterized by poorly drained

mineral soils and by plant life dominated by grasses

swamp

wetland ecosystem characterized by mineral soils with poor

drainage and by plant life dominated by trees

bog

type of wetland ecosystem characterized by wet, spongy,

poorly drained peaty soil with trees, shrubs, mosses

fen

similar to bogs but with less acidic soil, due to more ground

and surface water. Low shrubs prevail, with some orchids and

insect-eating plants.

Definitions of some Wetlands

6

Marsh

8

Swamps

Siberian peat bog

9

10

Walnut tip-over in wetlands

• Shallow soils

• High water table = shallow rooting 11

12

Organic soils can be fun too!!!

13 Histosols

14

A soil association common in the Puget Sound area

showing soil type relative to different glacial deposits

15

Histosol

(organic soils)

peat and mucks

Land Uses for Wetlands?

• Natural, wildlife refuges,

aesthetics, recreation

• Building on wetlands

–Drain – what happens?

• Mineral – oxidizes

• Organic – decomposes

• Agriculuture

Horizon Name Decomposition

stage

Oi Litter

(fibric) Low

Oe Peat

(hemic) Medium

Oa Muck

(sapric) High

Characterization of Organic Horizons

17

Seattle Soil Series

Oap 0 to 11 inches;

Oe 11 to 17 inches;

Oa1 17 to 21 inches;

Oa2 21 to 35 inches;

O'e 35 to 60 inches;

Agriculture on wetlands

19

20 http://en.wikipedia.org/wiki/File:Verschiedene_Typen_von_Pflanzenkl%C3%A4ranlagen.jpg

Surface flow

Subsurface flow

Vertical flow

Constructed Wetlands

22

Week 6 Field Trip • Organic Soil Formation and Use

Stops for Today

• Mercer Slough

– Commercial Development

– Agricultural use

• Larson Lake

– Agricultural use

• Issaquah Constructed Wetland

– Storm water infiltration

Connecting it Together

• Site Characteristics

– Soil forming factors

– Human alteration of the landscape

– Current day land use

• What do you learn from the example?

• Extend these lessons to other applications

Further Development

• Proposed light rail route

• Further development in wetlands

• Keep this in mind

– Bellefield office park

• See you right at:

– 9:30am or 1:30pm in Bloedel 211

• Bring

– Coat

– Rite in the Rain notebook