Groundwater

Water is continually circulated on earth. It evaporates from oceans, lakes and rivers, and then falls back on the land in the form of rain or snow. Some of this precipitation runs off the land back into surface waters, some is lost by evapotranspiration, and in New York State about 17% drains back into the land recharging the groundwater.

Because, in the United States nearly 80% of all community water supply systems rely upon groundwater. Only 20% rely on surface waters. Most rural dwellers and farmers depend upon their own wells for good quality groundwater. In New York State, some 6.2 million persons use groundwater as their source of water.

Since groundwater is located underground, it typically requires less treatment in order to be drinkable. Therefore, it is an extremely economical way of ensuring good potable water as long as we protect it from contamination.

Groundwater provides water to lakes and streams so they can continue to flow even when weeks have gone by without rainfall. Thus, quality groundwater is needed to maintain fish, insects, and animals that live in or use these water bodies.

Precipitation sinks into the soil and through cracks and spaces in the soil, sand and rocks. Typically, a top layer of soil, sand or stone in our area may be moist but all crevices and pores are not filled entirely with water. This is called the unsaturated zone. Soaking rain and snow melt infiltrate through this unsaturated zone until hitting the water table, or that level (which is never flat) where all cracks and pores are saturated with water. The water table level moves up and down depending upon the weather and season. It can be just a few feet from the surface or a hundred feet down. Usually the water table, which is constantly changing, is deep beneath high ground and hills and shallow beneath valleys.

Each sediment and type of rock has a different amount of pore space (porosity) available to hold water. Sand can hold about 30% of water in the spaces between the 70% sand particles. Fractured ledge rock might hold 2% of water in crevices to 99% of solid rock. The type of sediment and rock formations are key to how much groundwater can be pumped and how long will it take to refill or recharge what was taken.

Groundwater can be thousands of years old, but most has been underground for less than a couple of years. It is constantly being recharged by soaking rains and snow melt, except in latitudes like ours where freezing is common inhibiting recharge until the soil thaws out in the spring . Water underground is always moving; the speed depends upon geologic conditions.

An aquifer is any soil and/or rock formation that contains enough groundwater to be used for drinking water, industry or agriculture. Large underground amounts of clay or silt mixed with stones result in low yield aquifers of less than 10 gallons a minute. (Half a gallon per minute provides 700 gallons a day.) These recharge from local rainfall. Different rock structures the contain water in their fractures, fissures, and cracks are termed variable yield aquifers. Yields from these wells can vary from less than 1 gallon per minute to 500 gallons per minute, and they recharge from a large area. In New York State, the highest yields of water come from aquifers formed by sand and gravel during glaciation. (Valleys where glacial meltwater streams flowed usually contain extensive sand and gravel deposits.) Sometimes these high yield aquifers can reach thousands of gallons per minute.

What Aquifers Are In the Boquet River Watershed? Most of the Boquet River watershed is made up of variable yield aquifers (one person may drill 100 feet before reaching an adequate water supply while a neighbor has to drill 400 feet), and unconsolidated deposits of sand and gravel along the river valley. Groundwater in the latter can be particularly susceptible to contamination because of the high permeability of the deposits and shallow depth to the water table.

aquifers in the Boquet watershed,
blue indicates aquifers
(although the best available, the map is innaccurate -
the location of the aquifers is fanciful;
note that the Northway is not even in the correct place)

Amendments to the Safe Drinking Water Act in 1996 mandated the development of a "Source Water Assessment Program" (SWAP) in every state. In New York, the state Department of Health is delineating the area from which each public water system receives their water thought the use of hydrogeologic mapping, analytical methods, and numerical models. They are also studying all water supply and problem records, collecting census data to determine prevalence of septic systems, reviewing pesticide reporting law data and agricultural environmental management data. The SWAP program is also putting on workshops and symposiums so local officials and residents can become aware of the program and participate in it, since partnerships in assessment and protection procedures and part of the plan. To learn more, see http//:www.health.state.ny.us and search on SWAP or the Well Head Protection Program.

Thanks to the SWAP program, community systems are becoming safer. However, well owners throughout the Boquet River watershed are responsible for implementing safety measures for their own systems.

A good short booklet is "Ground Water and the Rural Homeowner" (1994) by the U.S. Geological Survey, Branch of Information Services, Box 25286-0046, Denver CO 80225.