Photo by: I. Hemingway

Whether it falls from the heavens, or squirts from the end of a garden hose, clean, fresh water is vital to the well being of the people, plants and animals that share your home landscape, neighborhood, region, and planet.  Here on Cape Cod, we are blessed with an average annual rainfall of 45 inches on the upper cape and 40 on the lower cape.  This generous gift of rainfall typically reduces the need for supplemental watering of our landscapes to just a few months out of the year.  But did you know that below your feet lies another blessing?  A vast source of fresh water known as the Cape Cod Aquifer spans nearly the entire peninsula.  An estimated 270 million gallons of water flow through this sole source aquifer every day, providing us with 96% of our fresh water.

               When it rains, about half of that rainfall percolates down through the cape’s porous soil to recharge the aquifer.  The aquifer, in turn, feeds the majority of the Cape’s surface bodies of water such as ponds, rivers, streams, marshes, and bogs.  Less than 1% of our rainfall runs off into these bodies of water.  Eventually, the groundwater discharges into coastal waters; Cape Cod Bay, Buzzard’s Bay, the Cape Cod Canal, the Atlantic Ocean, Vineyard and Nantucket Sounds. The remainder of the cape’s precipitation evaporates or transpires back to the atmosphere.  The aquifer is currently in a state of dynamic equilibrium; measurements of the water level in the aquifer have not shown a long term change.

               While the permeable nature of  our soil facilitates recharging the aquifer, it also makes the aquifer and associated surface waters vulnerable to contamination.  Whatever is applied to your landscape, or put down your drain, may offer the potential for contamination.  Contamination can threaten drinking water supplies, human health, and wildlife, especially aquatic life.

Photo by: T. Hemingway

Pesticides, fertilizers, nitrogen and phosphorus from septic seepage, road salt, disease causing organisms, solvents, cleaners, petroleum compounds, pharmaceuticals,  hormones,  household products like soaps and lotions, insect repellents, perfumes and other fragrances, sunscreens, hand sanitizers and suspended sediments all have the potential to cause contamination.

               A major contamination site on Cape Cod is the MMR (Massachusetts Military Reservation) Superfund Site.  The MMR is located on the upper cape in parts of Bourne, Mashpee, and Sandwich and abuts Falmouth.   Here, at least 16 groundwater plumes contaminating the Cape Cod sole source aquifer, and close to 80 source areas in the overlying soil, have been found.  The contamination, resulting from leaking fuel pipelines, munitions and fire training areas, motor pools, landfills, and sewage treatment plants, frequently includes toxic volatile organic compounds (VOCs).  Some examples of VOC’s are fuel additives such as ethylene dibromide (EDB), and solvents such as tetrachloroethylene (PCE), trichloroethylene (TCE), and carbon tetra-chloride (CCl4).  Total cost for the cleanup is estimated to be $850 million and will take up to 50 years to complete.

Photo by: T. Hemingway

Eutrophication is the process in which oxygen is removed from water by the decomposition of large amounts of organic matter.  Nitrogen and phosphorus from soluble fertilizers used in both commercial and residential situations and human wastewater released from septic systems are carried into the aquifer. Once in the ground water, these nutrients can move into ponds, marshes and estuaries, causing explosive growth of algae.  The algae, in turn, die and rapidly decay, which depletes the oxygen in the water.  Without oxygen, shellfish, fish and other organisms die, and the ecosystem collapses.  In Falmouth, for example, once productive salt ponds where vibrant scallop fisheries existed are now closed to shell fishing due to eutrophication.  This form of contamination is common throughout Cape Cod.

                Whether you live on Cape Cod or elsewhere, conserving and protecting your fresh water supply is tremendously important to you.  It is clear, that what we do, how we behave, will have impacts well beyond our individual property lines. Individually and collectively, we can make a difference.  In the spirit of conservation and protection of our water, here are some thoughts for your consideration:

Photo by: I. Hemingway

                Water deeply and infrequently.  Water to a soil depth of 6-12”.   This promotes the development of a deep root system.  Use a spade to check the depth of penetration.  Keep the interval between waterings as long as possible without plants showing signs of stress. 

                Invest in a rain gauge.  Most plants that grow in our area need 1-2 inches of water per week during the growing season to remain healthy.  Even native plants can become drought-stressed during extended periods of low rainfall.  If your rain gauge indicates you have received less than 1” of rain in a given week, consider watering.

                When you water, set out coffee cans in the path of the sprinkler or irrigationhead and time how long you need to run the water to get 1-2” of water in the can.  Also, you can see if the water is being distributed uniformly.  If water runs off before 1-2” is applied, stop watering and let the area drain before resuming.  Aerate your lawn in the fall if you have compacted areas.  Water will run off compacted soil.

                Water early in the morning, after the dew has formed.  If your plants are “gasping” (wilting), afternoon or evening waterings are OK, but only in a pinch.  Routine afternoon watering wastes water due to evaporation and repeated evening waterings can promote fungal growth.  Avoid watering hardscape surfaces (walks, drives, patios, roads, etc.)  When practical, water trees, shrubs and perennials separately from lawns. Use soaker hoses to efficiently water planting beds.  Use native plants whenever practical.  Keep lawn areas small.

                Set your mowing height to 3” in the summer.  A larger leaf area encourages a larger root system. Keep your blade sharp.  A jagged cut speeds moisture loss.

                Use slow release fertilizers, preferably from an organic source.  They stay in the root zone longer and are less likely to pollute water supplies.  Avoid over applying.

Photo by: I. Hemingway

                Tolerate a few weeds and insects.  If a population becomes too large and you need to reduce it, choose the least toxic method to gain the desired level of control.  Keep applications to a minimum.  Always read, understand and follow the directions on the pesticide label. THE LABEL IS THE LAW!

                Lastly, be mindful of what you put down the drain.  Eventually, it will end up in our aquifer, our ponds and estuaries and our drinking water supply.  Some things should never be put down the drain. Gasoline, motor oil, pesticides, solvents (paint thinner), certain paints, soaps containing high levels of phosphate and some pharmaceuticals are no-nos.  Check the label. If you’re still not sure, research it first.

                Remember, we are all in this together!  It’s our water.