What About Wetlands?

What exactly is a wetland? We’ve all heard the term ‘wetlands’ used here on the coast. Would you recognize a wetland if you saw it? Do you live near one?

This paper is an attempt to define ‘wetland.’ While we can begin with a dictionary, we really need to understand the role that the term plays in our lives and in our environment, right here on the San Mateo County Coastside.

A short dictionary definition tells us that a wetland is “a low area where the land is saturated with water.”

The USGS defines a wetland as “a general term applied to land areas which are seasonally or permanently waterlogged, including lakes, rivers, estuaries, and freshwater marshes; an area of low-lying land submerged or inundated periodically by fresh or saline water.”

Is the definition of wetland the same for regulatory purposes? Under the Clean Water Act, The Environmental Protection Agency defines wetlands as “those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas.”

(A list of the types of wetlands as classified by the EPA is located at the end of this article.)

 Focusing in on a more local level, wetlands are defined under the California Code of Regulations as “...land where the water table is at near, or above the land surface long enough to promote the formation of hydric soils or to support the growth of hydrophytes, and shall also include types of wetlands where vegetation is lacking and soil is poorly developed or absent as a result of frequent drastic fluctuations of surface water levels, wave action, water flow, turbidity or high concentration of salts or other substances in the substrate. Such wetlands can be recognized by the presence of surface water or saturated substrate at some during each year and their location within, or adjacent to vegetated wetland or deepwater habitats.” (14 CCR 13577)

Here on the Coastside most of the EPA listed types of wetlands do not occur due to our rainless summers. We have tidal marshes, identified by periodic tidal inundation. Pescadero Marsh is an example of a protected tidal marsh. Regulations exist as to the uses of tidal marshes. Because of the influence of tidal action on tidal marshes they should not be difficult to identify.

The most common form of wetland encountered on the Coastside is the vernal pool.

What is a vernal pool?

The EPA says: “The term vernal pool originally referred only to small, intermittently filled wetlands found in the Mediterranean-type climate of the western United States. Today it is used more broadly to include other small ephemeral wetlands found country-wide.”

Other definitions of ‘vernal pool include:

“A type of marsh found in Mediterranean-type climates (i.e., wet winters and dry summers), especially on coastal terraces in southwestern California, the central valley of California, and areas west of the Sierra Mountains, that is characterized by shallow, seasonally flooded wet meadows with emergent hydrophytic vegetation.” (reference)

“A seasonal wetland formed in depressions having a specific geology and hydrology, which directly influence the plants and animals found within.” (reference)

“Vernal pools are seasonally flooded depressions found on ancient soils with an impermeable layer such as a hardpan, claypan, or volcanic basalt.” (reference)

This is a good time to take a look at some of the terminology we’re running into.

Hydric Soil: A type of soil with characteristics resulting from prolonged saturation and chemically reducing conditions such as occurs under anaerobic conditions. (See Anaerobic Soil below.)

Anaerobic Soil: Soil that is devoid of interstitial oxygen. In wetlands this condition most normally occurs because of the sustained presence of water, which limits contact with the hydrology

Hydrophytic Vegetation: Plants that have adapted to living in aquatic environments. These plants are also called hydrophytes. In wetlands, hydrophytic species occur where at least the root zone of the plant is seasonally or continually found in saturated or submerged soil.

 (from http://www.coastal.ca.gov/wetrev/wetglos.html)

We're not even close to running out of wetlands definitions. Besides the federal government in the form of the EPA, we have other federal, state, regional and local definitions of wetlands.

A handy little publication, Guide to Creek & Wetland Project Permitting from the San Mateo Countywide Stormwater Pollution Prevention Program (download from the Planning and Building Department of San Mateo County) offers pointers to help you through the permitting process. Here’s one: “Should you have a project that is adjacent to or involves a riparian corridor or wetland, certain permits may be required from Federal , State or local agencies. These agencies have their own specific definitions of sensitive areas that require permits. This pamphlet should help you determine which agency to contact  for your project.”

Let's list some of the agencies that define and regulate wetlands, according to the pamphlet:

III.              Federal:

A.     Army Corps of Engineers

B.    US Fish and Wildlife Service

C.    US National Marine Fisheries

D.    U.S. Natural Resources Conservation District (partners with RCD)

IV.              State:

California Department of Fish and Game

V.                Regional:

A.    Regional water quality control boards

1.            California State Water Resources Control Board

2.            Bay Area Water Board

B.   California Coastal Commission (within the coastal zone) 

VI.              County

A.    San Mateo County Planning Department

B.    May do CEQA Reviews

C.    San Mateo County Resource Conservation District

VII.            City of HMB Planning Department  (CEQA Reviews)

You will not have to deal with all of those agencies for each wetland project. Download The Guide to Permitting pamphlet. It details the interests of each agency and has a handy checklist to indicate who you might want to contact in planning your project if it is close to or involving a wetland. (There is also the ‘potential wetland,’ but we’ll get into that in a later article.).

Unfortunately, the pamphlet is no help in determining the definitions various agencies have for wetlands. And no wonder. Some definitions are “not for regulatory use” and others are. Are we clear on the definition of wetland? I don’t think so. When differing agencies have differing definitions, the permitting process can become even more confusing.

At this point we might be able to conclude (in plain English) that in most cases: a wetland has a certain amount of saturation, certain types of plants suited to live in that environment, and soils that support such life.

Next time I’ll wade into the murky waters of the Coastal Commission, Local Coastal Plans (San Mateo County and City of Half Moon Bay) to see what they say about wetlands.

Types of Wetlands
as defined by the EPA

A.     Marshes

1.    Tidal

2.    Nontidal

a.   Wet Meadows

b.   Prairie Potholes

c.   Vernal Pools

d.   Playa Lakes

B.     Swamps

1.    Forested Swamps

a.   Bottomland Hardwoods

2.    Shrub Swamps

a.   Mangrove Swamps

3.    Bogs

a.   Northern Bogs

b.   Pocosins

4.    Fens