This was originally posted to: Guemes Island Environmental Trust

Water, Water Everywhere Part 1

Water, Water Everywhere, But...

Water, water, everywhere, And all the boards did shrink;
Water, water, everywhere, Nor any drop to drink.

At first glance, the drought predicament of the Ancient Mariner has nothing to do with life on an island. But a little reflection changes that perception. An island environment is like the Ancient Mariner's ship: a certain store of fresh water exists, but beyond that is the undrinkable salt sea.

Ground Water-A Sole Source Aquifer
The fresh water resource on Guemes is ground water. Fresh water collects underground in pools or layers called aquifers. Because this is an Island, salt water surrounds the fresh water just as it encircles the entire island. A simple diagram of this naturally occurring phenomenon is seen here:



Underground, the fresh water pools up on top of the seawater because it is less dense than the seawater. Seawater has a density of 1.025 which Is heavier than the density of freshwater at 1.00. In natural conditions, the altitude of the underground fresh water table is higher than sea level and decreases toward the beaches. At the interface between the fresh and salt water is a zone where mixing occurs called the zone of diffusion. If fresh water is pumped from the aquifer faster than it can refill, then the salt water moves inward and upward. The rate at which the aquifer refills Is called the recharge rate. Salt water moving Into the aquifer Is called salt water intrusion.

The diagram used below is simple, but the basic principles hold true for any island. The ground water picture under Guemes is more complex. Geologically, the island has two basic formations: 1) the large rock outcropping that forms the southeastern end of the island (which some call Mt. Guemes) and 2) the rest of the island which is glacial deposits. Mt. Guemes Is fractured rock, ophiolite, one-hundred-million-year old ocean floor forced upward during the formation of the Cascade Mountains. The majority of Cypress Island is the same type of formation. The glacial deposits that form the rest of Guemes are some 500,000 to 2,000,000 years old-young, geologically speaking.
The glacial deposits are not simple, uniform layers but a mixture of laterally discontinuous layers composed of sand, gravel, clay and even some lignite, a lowgrade coal which was probably peat bogs at one time. Covering the sediments at various depths is topsoil formed by the forests.

The fresh ground water is mostly pooled in the sand layers of the glacial sediments. On Mt. Guemes, the fresh water that exists is contained in the many fractures of the ophiolite rock. Although there are two distinct geological areas on the island, that does not necessarily mean that there are two aquifers. Two basically different water chemistries exist depending on whether the water is from the rocky area or the glacial sediments, but the number of distinct aquifers is simply not known.

The complexity of the glacial sediments covering the island makes it difficult to predict the underground picture. It seems that most of the wells in the glacial sediment areas of the Island terminate at about the same level; generally within about 30 feet of sea level regardless of the altitude of the well head. That does not mean, however, that they are using the same aquifer. The degree of communication among wells and aquifers is unclear at this time. Also the amount of fresh water available under the island is unknown.
One thing that is known, however, Is that the fresh water beneath Guemes is sole source. Water that Is pooled beneath Guemes Is not coming from anywhere but Guemes. The salt sea surrounding the island cuts off other sources of fresh water. There are no above or under ground fresh water rivers flowing by the island. According to geologists, water from the Cascades or Mt. Baker is not welling up through the rock of the ocean floor to recharge the island's water. The water in the aquifer(s) under Guemes is the only fresh water source. Thus the term "sole source aquifer" applies to the fresh water supply on the island.


How Much Fresh Water Is There?

Clay or hardpan has a significant presence in the island's makeup as many know who have had the miserable experience of digging into it. Rain water falling on the island does not permeate the clay layers. This raises another question. The usual assumption in accessing a water resource is that the aquifer(s) under the island are recharged by rainwater. With so much day, however, it is not clear how much of the rain water is getting into the island reservoirs. The possibility exists that we are drinking water left trapped in the glacial sands by the melting ice of the last ice age. Ibis possibility can be tested because the old water can be fingerprinted by examining the type of oxygen (the ratio of the isotopes 18 and 16) that makes up the water molecules. The island is fortunate in having John Oldow as a resident. Oldow, a professor of geology and geophysics at Rice University, grew up on Fidalgo Island. He is working on the question of old water and reservoir mixing.


Guemes Island Water Types

These two diagrams characterize the two main types of natural groundwater on Guemes Island. Calcium-magnesium carbonate water is predominant in andnear the rocky southeastern portion of the island. Sodium-chloride type water dominates most of the remaining island ground water.

-Dave Garland, Hydrogeologist Washington State Department of Ecology

Last winter, ten samples of water, eight from wells and two surface-water samples, were collected for oxygen isotope analysis. The analyses are currently underway in the stable isotope laboratory at the Department of Geology and Geophysics at Rice University and the results are expected by mid-July. When the results are available a detailed report will be made to the newsletter.

The objective of this study is to gain a first-order understanding of the water aquifer system underlying the glacial sediments of Guemes. The results are not expected to be conclusive but may be sufficient to help document our need for a detailed hydrology study of the island. Two things may emerge from the preliminary work, however. First, it is possible to assess whether or not the fresh water underlying the island is meteoric (recharged by rainfall) or whether It is ancient water deposited during the last Ice age. It is unlikely that our water is solely derived from an ancient source, considering the seasonal nature of salt water intrusion on West and North Beach. On the other hand, we cannot automatically exclude the possibility that some component of the water may have an ancient source. The possibility of a mixed source can be tested with the isotope data.
The second goal of the study is to see if the aquifers underlying the island are In communication. If the isotopic values are essentially the same throughout the island (and not solely derived from meteoric recharge) a good argument could be made for island-wide connection of the aquifer system. If this contingency exists, it is clear that problems that develop in one part of the Island may ultimately have an impact on other parts of our community.

Even if all of the ground water is recharging, we still need to know how much is going Into the ground and how fast. This is a very difficult question. About 25% of the rain that falls on a given area of normal ground ends up in the ground water. Almost every condition influences the infiltration rate, or the amount of rain the percolates into the ground water. The topography, the type of soil and the vegetation affect the infiltration rate. Rain water runs quickly off a steep, rocky hill side. On flat, forested land with coarse textured, gravely, sandy loam, the infiltration rate Is best.

How much of the island's geology, topography and vegetation is providing the best infiltration? It could be that certain limited areas of the island are yielding the highest infiltration of fresh water. In such locations, there will be lots of gravel and sand in the ground make-up and hopefully little logging to reduce the vegetation. At present, not enough is known about the island ground water source to speculate where the recharge areas are or what the recharge rate is.

Salt Water Intrusion

Salt water Intrusion is happening in certain areas of the island. Both on West Beach and North Beach, wells that once had good, fresh water have turned salty. Certainly, some of the wells in which salt water intrusion has occurred are shallow and near the beach. The differing density between salt water and fresh water explains why salt water intrusion is a problem and a major threat on an island.

Assume for a moment that most of Guemes has one large fresh water aquifer as most of the wells in the glacial sediments area are at about the same level to reach fresh water. The number of wells on the island has increased with the growing population. If the fresh water aquifer is being permanently pumped down, then the salt water will move inward and upward on all the beaches.

The U.S. Environmental Protection Agency recommends that the chloride concentration in drinking water be less than 250 mg/L(milligrams per liter). Above the 250 mg/L level, fresh water begins to taste salty to the average person. Uncontaminated ground water In most coastal areas in Washington contains about 10 mg/L chloride. Most studies conducted to date utilize the 100 mg/L chloride level to indicate salt water intrusion. (Chloride is a good indication of salt water intrusion because of the 35,000 mg/L of total dissolved solids in sea water, about 19,000 mg/L are chloride.) According to geologists, water from the Cascades or Mt. Baker is not welling up through the rock of the ocean floor to recharge the island's water. The water in the aquifer(s) under Guemes is the only fresh water source.

Having grown up on North Beach, this writer knows of three wells that once did not taste of salt water but now do. Most of the inhabitants of Guemes are still concentrated around the periphery and salt water intrusion is a problem that has increased. The exact causes are not known, but should be sought.

It is easy to assume that water is plentiful and always available. In an era when property values in the islands are increasing, and on some beaches, dramatically, evidence of salt water intrusion can destroy that value. Most banks simply will not loan on property were the well water is of poor quality or quantity.

An old argument runs that if the water on Guemes is insufficient or of poor quality, just pipe it in from Anacortes. This topic was recently discussed with the City of Anacortes Public Works Department, which is responsible for the city water. Today, Anacortes may have enough water to meet Guemes' needs, but the cost of piping the water under the deep Guemes Channel and then building the network of piping and pump stations on the island to serve the population would simply be too expensive to achieve any reasonable payback on the project. No financial mechanism exists to pay for such an expensive solution.

In the Meantime-Growth

Most of the water questions on the island remain unanswered. We know very little about the water resources of this island either in terms of quantity or quality, which is an issue in itself. In the meantime, growth is a continuing phenomenon on Guemes. For example, on property inland but immediately adjacent to the established homes on North Beach, work is under-way for development of nine new home lots.

When so much is unknown about the water resource, and with the continuing pressure of growth, the time has arrived to do a comprehensive study of the island's water. One avenue for a comprehensive study is the Centennial Fund administered by the State Department of Ecology. The fund, and the technical support provided by Ecology, result from the Centennial Clean Water Bill passed by the State of Washington in 1986.

The bill was passed as a tool to help control pollution of water resources. Salt water intrusion is one form of pollution. Through this fund, fifty percent of the necessary monies for a comprehensive study can be granted from the Department of Ecology. The other fifty per cent must come from local governments or those involved in the study. Hours of work on the study by local citizens can be counted as part of the 50% local contribution.

Alternatively, money for the study can be obtained in the form of a loan. If the loan is repaid in five years, no interest is charged. The term of the loan can be extended to 20 years but then there is an interest charge.

The cost of a study of the ground water resource is expensive due to its complexity. Also, a good study utilizes professional hydrological consultants. Estimates vary about the cost of the study and right now no one is certain how much a study would cost for Guemes. The cost of depletion or permanent damage to the water resource, on the other hand, could result in costs that dwarf the cost of the hydrology study. The results of the study can be valuable to all the residents of the island and with the participation of the various island groups, the study could become a reality for Guemes.

Waldron Island has completed such a comprehensive water study. Waldron was found to have plenty of recharge water for its needs except that the primary recharge area was threatened by a 450 acre development that was being planned on the island. The development in that location would have caused a major disruption to the island's water resources. Considering the potential for development and growth for Guemes Island and our current Ignorance of our water resource, an ecological nightmare could result.

Growth makes it necessary to obtain answers about the extent and quality of this island's fresh water resource. How much growth should continue in the meantime is a question of significant magnitude. Issues of water rights is a topic for another discussion but management of the resource, which can only be accomplished with thorough knowledge, is a wiser solution than being reduced to legal battles over island water.

The old time Guemes Islanders never assumed the water resource was unlimited. Water was always used wisely. No one watered grass. Watering was only for gardens. Showers were limited, taken like Navy showers, Taps were not absently left running. Guests who were Insensitive to careful water use were told about it. Perhaps the old timers at least sensed what they did not know and didn't take the island fresh water for granted.

-Steve Orsini with John Oldow


This article appeared in the Summer 1990 issue of The Guemes Island Environmental Trust Newsletter

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