Cook Inlet Wetlands

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The information here is intended for guidance, and should not replace any information provided by the US Army Corps of Engineers, or the US Environmental Protection Agency, the primary entities responsible for administration of section 404 of the Clean Water Act.

My site is wet, what does that mean?

A substantial portion of the Cook Inlet Lowlands is wet and these maps (links below) are intended to help identify areas likely to present problems for the builder, the neighbors, and valuable resources such as moose habitat and salmon streams if the areas are not well-managed.

Wetlands are not always obvious. You may visit the Kenai Peninsula Borough Interactive Parcel Viewer web site to get an idea whether or not your site is wet. Follow the directions to get set-up, then click on "Wetlands", under "Map Display" to view a wetland map along with parcel lines. You may also download a GoogleEarth file that shows Cook Inlet wetlands over the satellite imagery that Google Earth uses.

If your property, or a property that you may be considering for purchase is mapped as wet, then you should evaluate your decision to build or buy carefully. Three conditions might apply: 1) Your site may not actually be wet. The map was made at a scale describing a much larger area than most parcels, so the wetland boundaries may not exactly match with your property lines, particularly with small wetlands, or with properties at the edge of wetlands. 2) If your site is actually wet, then building will be more difficult than on high and dry ground. Driveways will require more fill material and maintenance, septic systems will be more expensive and prone to failure, and dry basements may be impossible to construct. 3) If your site is wet, and you decide to build or buy anyway, you will need a permit if you need to place fill in the wet part. Permits may be simple if your project is small, or permits may be very involved, or even denied, if your project is large and causes impacts to nearby property owners or high value resources such as salmon spawning streams.

Even if your site is not a wetland that is jurisdictional under section 404 of the Clean Water Act, you might encounter wet building conditions. This is especially true where the wetland maps show wetlands nearby (see the above links). For example, a water table that is two feet below the surface all year will not be jurisdictional, but still may present difficult building problems during foundation, road, and septic system construction.

What do the different wetland names mean?

Wetlands are not all alike therfore they are assigned different names, for example Kettle, Discharge Slope, and Depression. The different names are intended to reflect the different ways in which wetlands are of value to society. Some values include flood moderation, well-head protection and wildlife habitat. Increased flooding, decreased water quality, and loss of wildlife led to the regulation of placing fill material in wetlands.

Because wetlands are of value for different reasons, large projects requiring substantial fill are assessed in detail. The different wetland names aid in the assessment. Wetland assessmnet in Alaska is in its infancy. The abundance of different wetland types and the pristine nature of Alaska wetlands require an approach to assessment that is fundamentally different from the approaches used in the rest of the US. This wetland classification and mapping is a first step in developing an appraoch appropriate for Alaska.

Do I Need a Permit?

If the site is a wetland and you plan to place any fill material in the wetland you will need a permit. Permits are free, and many are covered under what are known as Nationwide permits. These permits cover common, small-scale activities such as driveways and house sites.

The three tiers in the permit process are, in order: Avoidance, Minimization, and Mitigation. Can you complete your project while avoiding wetland fill? If you cannot complete your project without avoiding fill, can you minimize the amount of fill needed? Once minimized, how can you mitigate for the loss of wetland area? Mitigation examples include wetland banking, or purchasing other wetland property for conservation. If you substantively address these issues in your permit application, the process will proceed more smoothly than if you do not.

The US Army Corps often will visit your site to make a jurisdictional determination (JD). In order to perform a jurisdictional determination, they will require a plan; they will not perform speculative JDs. A plan can be a clear, simple drawing.


Because of demand and limited staffing, US Army Corps personnel may not visit your site as soon as you would like. Although the permit is free, the time required may exceed your expectations. If you need a wetland determination faster that the Army Corps can provide a jurisdictional determination, you may need to hire someone to help you through the process. The Army Corps web site provides a list of consultants who request listing (653k .pdf file updated October 2013).

Visit the US Army Corps informative web site: Do I Need a Permit?

What Is A Wetland?

There are two terms used: wetland and upland, upland is used to mean the opposite of wetland. In the Cook Inlet area, any place where the water table is within about a foot of the surface for more than a couple of weeks of the growing season for more than half of all years generally qualifies as a wetland under the jurisdiction of section 404 of the Clean Water Act of 1974. In sandy soils the water table needs to be closer to the surface, about six inches, for a couple of weeks of the growing season. The growing season is defined using the 50% probability of the temperature being 28 degrees F or higher on a Natural Resources Conservation Service Water and Climate Center website. The major exception is where the wetland is surrounded by upland- i.e. not connected to Cook Inlet or another navigable-in-fact water body through other wetlands, lakes or streams. Wetlands that are surrounded by uplands were considered jurisdictional until about 2001, and they may again become jurisdictional. Many states have laws that assert jurisdiction over wetlands surrounded by uplands.

How Do I Identify a Wetland?

Some wetlands are tricky to identify, especially those that barely meet the requirements described above. For example, if a site supporting a water table 8 inches below the surface for three weeks of the growing season is visited outside of those three weeks, wetland determination might be perplexing. Wetlands mapped with the map unit WU and in the Discharge Slope Ecosystem can be the most difficult to accurately identify.

If a site is included on either the GoogleEarth or Kenai Borough Parcel Viewer map that you may have used to get to this page, it still might not meet jurisdictional criteria. Wetlands mapped as Depressions or Spring Fens are the primary examples of sites that may not meet jurisdictional criteria. On the other hand, A SITE NOT ON THE MAP MAY STILL MEET JURISDICTIONAL CRITERIA AND REQUIRE A PERMIT. Although every effort is made to map all of the wetlands that meet jurisdictional criteria, the maps are good guides, not the final word.

Most wetlands are straightforward to identify. A few key technical characteristics help identify difficult wetlands outside of the period when a seasonally high water table is not close to the surface, for example during late July during a drier-than-average year. The plants and soils present are most important, although some other clues might indicate a seasonally high water table. The full procedures for identifying jurisdictional wetlands in Alaska are described in the 2007 Alaska Regional Supplement and the 1987 Wetland Delineation Manual. These extensive technical manuals include procedures and data sheets to help determine whether or not a site is a jurisdictional wetland. The procedures require significant technical experience identifying soil, plant, and hydrologic indicators.



Cook Inlet region map


Mike Gracz

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