SHORE STEWARDS NEWS
April 2009
Island County, Washington
Issue No. 54
This issue was prepared by staff from several WSU Extension Offices: Adria Banks (Skagit County) and Peg Tillery and
Fay Linger (Kitsap County). Septic pictures provided by Janet Hall (WSU Waste Wise Coordinator, Island County).
With the arrival of intermittent sunny, warm days and spring showers, many people are working in their
yards. This issue of the Shore Stewards News provides information on those less glamorous yard care
tasks. Read on for information on disposal of yard waste and landscaping over septic system drainfields.
Our yards often serve as a way for us to connect with our surroundings. Practice one or more Guidelines
for Shoreline Living to ensure that you aren't negatively impacting Puget Sound during your yard
activities!
Yard Waste Disposal
For many of us the first warm, dry days of spring mark the beginning of the mowing
and pruning season, which continues until the last temperate days of autumn.
Maintaining our lawns and yards means that we have grass, weeds, and plant cuttings
to handle. Living along the shore, near a green space or on a bluff, one might be
tempted to simply dump all those clippings over the edge of the bluff or bank and onto
the beach below. The waves will just wash it away, right? Well, maybe, but maybe
not. Besides creating an unsightly, decomposing pile on the beach, dumping yard
waste can be hazardous for wildlife and for your own property.
The Problem: If you use fertilizers or pesticides on your lawn, those chemicals are delivered to the high
intertidal when you dump grass clippings onto the beach. This part of the shore is damaged by the chemicals
that we might use on our lawns and we run the risk of poisoning fragile marine life.
Even if you don't use any chemicals, grass clippings on the beach are problematic for several reasons. Piles of
dumped grass rarely "wash away" - instead they accumulate on the beach or at the foot of your bluff. Like most
untended, unbalanced compost piles, this accumulation of debris won't decompose quickly. Instead, dumped
yard waste piles up, potentially suffocating plants and other organisms beneath it.
Grass clippings dumped over a bank or bluff can create additional dangers. By smothering native plants under
yard waste, we run the risk of killing the vegetation and its sturdy roots that protect the toe of your bluff from
erosion. Additionally, piles or mats of grass and plant clippings lying against the bluff can create weight or
absorb our occasional summer rains, thereby increasing the weight of the slope and making the bluff more
vulnerable to slides. If your neighbor is dumping on their bluff property, you might ask them to stop for both
your sakes. Your properties are connected, and a slide on their property can contribute to one on yours.
It isn't just residents on bluffs that should be concerned about dumping yard
waste. Grass clippings are high in nitrogen, which means that they leach
excess nutrients and create high heat as they decompose. In addition to
suffocating native plants at the bluff's toe, decomposing grass clippings can
create low-oxygen, high heat areas towards the top of the beach - an area
used by spawning forage fish. Forage fish are a critical component of our
Puget Sound food web - destroying forage fish eggs or spawning habitat has
Photo by Joan Gerteis, 2006, Island
County Beach Watcher
the potential for severe repercussions for salmon, seabirds, and marine mammals. Additionally, excess nutrients
leaching out of our green waste can lead to algal blooms. As the algae or phytoplankton use up the excess
nutrients, they start to decompose, and decomposition uses up oxygen, creating low oxygen conditions harmful
to marine life.
Some Options: Clearly our yard waste doesn't belong on the beach or in Puget Sound. One option is to reduce
or eliminate lawn by planting native plants that don’t need mowing and only minimal trimming. This might be
especially attractive to bluff property landowners as a wide buffer of low-growing natives between your lawn or
garden and the bluff edge won’t block your view and will also be a low-maintenance, water-free zone that you
won't have to mow and will also keep the weight from excess watering away from the bluff.
If lawn reduction and native plant buffers aren't an option, the easiest thing to do is to use a mulching mower.
Set your mower higher (1-2"), mow frequently, and the mower pulverizes and shoots the grass down to the soil.
This fertilizes and waters your lawn (since grass is over 90% water), and you save time and energy by not
bagging or disposing of clippings. If this won't work, you can create your own compost pile, preferably away
from the bluff, which would also supply you with compost for your garden or other yard plants. Alternatively,
many counties now offer yard waste recycling for reasonable monthly fees. For those of us in more rural areas,
these door-to-door programs might not be available, but check with your local Solid Waste facility to verify that
you can deliver and dispose of your yard waste there.
Landscaping Septic Drainfields and Mounds
How to landscape a drain field and around mounds is an often asked
question by septic system owners. The drainfield size and shape varies
based on the type of system you have. Regardless of the type, a good
rule of thumb for landscaping over drain fields is to use shallow rooted,
drought tolerant plants with non-dense roots. Ongoing watering is not
encouraged. Here are some recommendations to consider.
Vegetables: One of the most common questions about landscaping
drainfields is "Can I plant a vegetable garden over the drainfield?" The
answer is, “It is not recommended.” Vegetables often need daily
watering and excess water in the soil reduces its ability to filter and
treat wastewater. Also, if the tank is not functioning properly the
drainfield could contaminate the vegetables and make them unsafe to
eat.
Conventional / Gravity Fed System Drainfield
Tree and shrub set backs: Large trees and shrubs should be avoided over the entire area and setbacks for these
larger plants should be followed. Trees and large shrubs should be at least 30 feet away from the drain field.
One reason is to prevent tree roots from getting into and breaking the pipes or even into the septic tank.
Lawns: Grasses with their shallow root systems are the simplest and most frequently recommended plantings
over the drainfield. Choose a traditional lawn (remember to fertilize only in the spring and fall, if at all), or
choose an unmowed meadow. You may include permeable pathways, garden ornaments, tables and benches. If
a mowed lawn is your priority, use grass seed mixes suitable for our Northwest climate, and mixed specifically
for sun or shade depending on the site of the leach field.
Meadows: Wildflower meadows are frequently suggested for drainfields but in reality they are difficult to
maintain. Perennial seeds in the meadow mixes, such as lupines, tend to take over and the annual seeds included
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in with the mixes do not always sustain themselves for more than a year. If you wish to try a wildflower
meadow mix make sure it is for the Northwest and does not contain seeds or plants on the Washington State
Noxious Weed list. You may want to try one of the various "eco" lawn mixes available through Northwest
nurseries and catalogs that are a blend of grasses and wildflowers that require a minimum of water, fertilizer and
mowing.
Perennial Gardens: In sunnier locations, perennial gardens can be created with mixes of ornamental grasses of
different heights and can be inter-planted with ground covers, small bulbs, and sun loving perennials as well as
smaller, shallow rooted shrubs. Some sun loving perennials are daffodils, narcissus, tulips, daylilies, crocosmia,
lavenders, heathers, astilbes, and meadow rue (Thalictrum aquiligiifolium). Some shade tolerant options include
Solomon's seal (Polygonatum
biflorum), trillium (Trillium sp.), Pachysandra (Pachysandra terminalis), Wintergreen (Gaultheria
procumbens), Lily-of-the-valley (Convallaria majalis), and False lily-of-the-valley (Maianthemum dilatatum).
Ferns can be used in shadier locations, but the larger ones, like Sword and Giant Chain Fern should be avoided.
Ornamental Grasses: The larger grasses are known to harm septic fields. Avoid Miscanthus, Pampas grass and
any Bamboo. Make your selections from the many smaller varieties, evergreen or deciduous.
Glendon Biofilter Mounds
Mound Gardening:
Glendon Biofilters consist of a septic tank, pump tank and above ground mounds
over the basins used to filter the effluent from the tanks. These mounds could be
called "conspicuous" and perhaps "challenging" to landscape.
Many homeowners block off the view of the mound area with hedge plantings or
decorative fencing. Care should be taken that the plants chosen for a hedge
should be kept about 4 feet away from the mounds to allow for maintenance of
both the mounds and the hedge. The plants chosen should not have aggressive
runners or roots. Avoid hedges of any of the native evergreen trees such as
Western Red Cedar and Hemlock. Laurels should also be avoided. Use more
"friendly" plants such as California Wax myrtle (Myrica californica) or smaller,
slower growing boxwoods. The wax myrtle will grow tall and may need to be pruned.
It is desirable to plant the mounds with a ground cover type of plant to prevent erosion of the sand and to help
them blend into the landscaping. There are many ground cover plants available in the nurseries and their tags
will tell which are suitable for sun or shade. Examples of suitable plants for ground cover on the mounds are
Coastal strawberry (Frageria chiloensis); Kinnikinnick (Arctostaphylos uva-ursi); Wintergreen (Gaultheria
procumbens); Creeping rubus (Rubus pentalobus); Sweet Woodruff (Galium odoratum) and Dwarf periwinkle
(Vinca minor).
Resources
For more information on Septic Systems visit these websites:
 www.dol.wa.gov - WA State Dept of Licensing - to find out if your designer/engineer is authorized to
provide design services
 www.wsg.washington.edu - Washington Sea Grant Program - click on Septic Sense for information
regarding onsite sewage systems
 www.doh.wa.gov - WA State Department of Health - Search for "Wastewater"
 http://www.islandcounty.net/health/liquid/HOST.htm - Island County Public Health information on new
Island County septic regulations, and how to register for classes to learn how to inspect your system.
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Events/Activities
Recycle Your Old Tires at Reduced Cost on May 9th - There will be a reduced cost tire recycling event
on both Whidbey and Camano on Sat., May 9, 10 am - 2 pm. On Whidbey, go to Coupeville Solid
Waste Facility, 20018 SR 20, behind recycling facility. On Camano, look for signs on Can Ku Road,
behind the CASA Animal Shelter on N. East Camano Drive. You can get rid of those old tires taking up
room in your yard and garage. You'll also be ridding your property of a mosquito breeding ground: the
puddle in one tire can breed up to 25,000 mosquitoes in a season! Volunteers from WSU Waste Wise
and WSU Beach Watchers will be accepting tires at a greatly reduced rate from the regular Transfer
Station prices. Tires should be reasonably clean, not full of dirt or Styrofoam. Passenger and light truck
tires are accepted for $2.25 each off rim, and $4.00 on rim. Please call for arrangements if you have a
load of over 100 tires. No large truck tires, tractor tires, motorcycle tires or airplane tires accepted,
sorry. For additional information on Whidbey, call Janet Hall at (360) 678-7974, or email
halljn@wsu.edu . On Camano, call Scott Chase, (360) 387-3443, ext 258, or email schase@wsu.edu.
Grow Your Own Shellfish, May 27th - Want to learn how to grow your own shellfish? Come to an
informational presentation by Bill Dewey, Public Affairs Manager for Taylor Shellfish Company and
owner of Chuckanut Shellfish, Inc. This discussion is free and will take place at 7:00 pm on Wednesday,
May 27th, at the Camano Community Center, 141 N. E. Camano Drive, Camano Island. Questions or
directions: (360) 387-3443, ext. 258
………………………………………………………………………………………………………………………
This product was funded through a grant from Washington State Department of Ecology. While these
materials were reviewed for grant consistency, this does not necessarily constitute endorsement by the
Department.
To view archived copies of past
www.shorestewards.org/island/newsletter/
Island
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Island County Shore Stewards is a program of the Island County Marine Resources Committee, and is
supported by WSU Extension in Island County and the Island County Marine Resources Committee, with
grants from the Northwest Straits Foundation and the Washington State Department of Ecology.
Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination
regarding race, sex, religion, age, color, creed, national or ethnic origin; physical, mental or sensory disability;
marital status, sexual orientation, or status as a Vietnam-era or disabled veteran. Evidence of noncompliance may
be reported through your local Extension office.
Website: www.shorestewards.org
email: shorestewards@wsu.edu
Contact: Shore Stewards Coordinator Scott Chase at schase@wsu.edu,
or phone 360-387-3443, ext 258
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