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Northern Tug Hill Glacial Aquifer

Support Document

  Jefferson, Lewis and Oswego Counties New York 

October 2006

      I. Introduction

      A. Statement of Section 1424 (e)

      The Safe Drinking Water Act (SDWA), Public Law 93-523, of December 16, 1974 contains a provision in Section 1424(e), which states that:

      If the Administrator determines, on his own initiative or upon petition, that an area has an aquifer which is the sole or principal drinking water source for the area and which, if contaminated, would create significant hazard to public health, he shall publish notice of that determination in the Federal Register. After the publication of any such notice, no commitment for Federal financial assistance (through a grant, contract, loan guarantee, or otherwise) may be entered into for any project which the Administrator determines may contaminate such aquifer through a recharge zone so as to create a significant hazard to public health, but a commitment for Federal financial assistance may, if authorized under another provision of law, be entered into to plan or design the project to assure that it will not so contaminate the aquifer.

      This section allows for the specific designation of areas which are dependent upon ground water supplies. Following designation, the review process will ensure that federal agencies will not commit funds toward projects which may contaminate these ground water supplies.

      B. Receipt of Petition

      On September 16, 2003 the Mayor of Lacona, petitioned the U.S. Environmental Protection Agency (EPA) to declare the Northern Tug Hill Glacial Aquifer, as defined in the petition, a Sole Source Aquifer (SSA) under the provisions of the SDWA. A notice of receipt of this petition, together with a request for public comment, was published in the Watertown Daily News on Sunday, July 9, 2006.

      C. Area of Consideration

      The area petitioned by Peggy Manchester, Mayor, Village of Lacona, NY, is the Northern Tug Hill Glacial Aquifer (Figure 1.), which supplies water to three towns in Jefferson County (Adams, Ellisburg, and Lorraine) and portions of two towns in Oswego County (Richland and Sandy Creek). A rural and agricultural population exists in this location. The Northern Tug Hill Glacial Aquifer, composed of glacial sediments covers bedrock on the western flank of the Tug Hill Plateau, as defined by T. Miller etal (USGS, 1989) covers approximately 14 square miles.

      II. Hydrogeology

      A. Geologic Setting

      The Tug Hill aquifer consists of glaciofluvial deposits, deltaic and beach sand and gravel of glaciolacustrine deposits that overlie till or bedrock. Glacial sediments are unsorted and poorly stratified deposits left by retreating glacial ice, such as till; glaciofluvial deposits are stratified and relatively well-sorted sediments deposited by streams that flowed from, on, within, or at the bottom of a glacier, such as outwash; and glaciolacustrine deposits are well-sorted and stratified fine sand, silt, and clay, such as deltas and bottom sediments that accumulated in impounded water caused by temporary closure of a basin by the ice front or by sand and gravel deposited as beaches along the shore.

      Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago. The lake was essentially an enlargement of the present Lake Ontario that formed because the St. Lawrence River downstream from the lake was blocked by the ice sheet near the present Thousand Islands. The level of the lake was approximately 30 m (~100 ft) above the present level of Lake Ontario.

      Lake Iroquois drained to the southeast, through a channel passing near present day Rome, New York. The channel then followed the valley of the Mohawk River to the Hudson River. The lake was fed by Early Lake Erie, as well as Glacial Lake Algonquin, an early partial manifestation of Lake Huron, that drained directly to Lake Iroquois across southern Ontario, along the southern edge of the ice sheet, bypassing Early Lake Erie.

      The prehistoric shoreline, marked by a ridge known as the Iroquois Shoreline, can be observed in places around Lake Ontario, for instance, in Toronto parallelling Davenport Road near Spadina Avenue, and also in Scarborough, Ontario, where the prehistoric shoreline takes the form of earthen cliffs at the modern lakeshore (called the Scarborough Bluffs).

      In the Tug Hill area, the coarse sediments that were deposited along the margin of the lake formed most of the northern part of the Tug Hill aquifer. Farther west, in deeper water, the finer particles settled to form the bottom sediments that now form part of the western boundary of the aquifer.

      Wave action along the shore of the lake eroded, and reworked these sediments, in a series of continuous linear beaches. Beach deposits that form part of the Northern Tug Hill Glacial Aquifer are identified in the section G-G' (Figure 2.) showing the stratigraphy of a typical offshore beach deposit near Adams. The beach deposit is thickest (20 to 50 foot) in a 10 mile reach that extends from 2 miles south of Richland north to Mannsville. Here many upland streams that drained the plateau to the east flowed into and deposited large quantities of sediments in Lake Iroquois.

      The beach deposits are thinner where no nearby streams were present to deliver sediment to the shore, and may be saturated during wet periods. This condition is found from Pierrepont Manor to South Sandy Creek and in some places in the 5 mile reach from Sandy Creek at Adams to Adams Center. The northern boundary of the Tug Hill aquifer is 1 mile north of Adams Center, where the Trenton Limestone rises to land surface and forms an escarpment.

      Deltas are fan-shaped, nearshore deposits of stratified sand that accumulated at the mouths of streams that emptied into a lake. Deltas also formed where meltwater that flowed on top of, or in tunnels within or at the base of the ice emptied into a lake. A large delta plain forms part of the northern part of the aquifer at a reentrant of the plateau near Adams. Sediments grade from sand and gravel along the edges to sand and silt in the central part. The western and north-eastern edges of the plain have 40 to 50 feet of sand and gravel that overlies 1 to 5 feet of till, which overlies bedrock.

      Lake bottom sediments are fine sand, silt, and clay that settled out of suspension in temporary glacial lakes form the side or bottom of the aquifer. Lake bottom sediments form the western boundary of most of the northern part of the aquifer.

      B. Ground Water Movement

      Precipitation is the source of all ground water. Precipitation in the Tug Hill region ranges between 45 and 55 inches/year, of which more than 60 percent falls during the nongrowing season. Not all precipitation is available for ground water recharge, however; some returns to the atmosphere through evapotranspiration, and some runs off as surface flow to streams and lakes. The remaining water, which is available to recharge the aquifer, is estimated to be 27 inches/year.

      Ground water generally flows westward and originates mainly from precipitation on the aquifer and indirectly from stream runoff from the till-covered uplands that seeps into the aquifer. The aquifer forms a wedge shape that thins to the east and is bordered by the underlying bedrock that slopes upward toward the east by till and lake deposits to the west. Ground water in this part of the aquifer discharges through numerous springs and wetlands along the west margin of the aquifer.

      C. Ground Water Use

      Ground water is the major source of water for residents living on or, in some places, adjacent to the Tug Hill aquifer. The population overlying the Tug Hill aquifer are summarized in table 1.

      There are four public water systems that currently derive their source from the Northern Tug Hill Glacial Aquifer. Indicated in Table 2., the total amount of water pumped from these municipal sources accounts for 91% of the total water consumed for drinking water in the aquifer service area.

      D. Ground Water Recharge

      Sources of recharge to the Tug Hill aquifer under natural conditions include (1) infiltration of precipitation that falls on the aquifer, (2) infiltration from streams that drain till-covered bedrock uplands and then cross the aquifer, and (3) unchanneled runoff from adjacent till and bedrock hillsides that seeps into the ground at the edges of the aquifer.

      Infiltration of Precipitation on the Aquifer

      Wherever sand and gravel are at land surface, surface runoff is minimal because nearly all rain and melting snow that is not lost through evapotranspiration infiltrates to the subsurface. The recharge from precipitation over the aquifer is approximately the amount of precipitation minus the amount of evapotranspiration. Average precipitation is 45 in/yr (inches per year) in the northern part; evapotranspiration is estimated to be 18 in/yr. Thus, it is estimated that annual recharge equals about 27 in/yr or 1.46 million gallons per day per square mile [(Mgal/d)/mi 2] in the northern part of the aquifer.

      Runoff from Adjacent Hillsides

      The recharge derived from runoff on hillsides is a function of annual precipitation, slope, permeability of hillside materials, and the size of the areas that slope directly toward the aquifer. The northern part of the aquifer is bordered by till-covered bedrock hillside only on the east. Only a small quantity of rainfall can seep into till before runoff begins because the till is relatively impermeable. Where upland hillsides slope directly toward the aquifer, unchanneled runoff infiltrates directly to the water table at the edges of the aquifer.

      Infiltration from Streams

      Streams that flow from till-covered uplands onto the permeable sediments that form the aquifer can contribute significant amounts of recharge. Where the water level in the aquifer is lower than the stream-water level, stream water can infiltrate into the aquifer. The rate of infiltration to the aquifer depends, it should be noted, on the permeability of the aquifer rather than of the streambed itself.

      Estimates of annual recharge from tributary streams are calculated by multiplying the length of the stream reach by the measured infiltration rate. Results of seepage measurements on for streams have an infiltration rate of 10 (gal/day)/ft for areas of sand and 100 (gal/day)/ft for areas of sand and gravel.

      In some parts of the aquifer, those where sand and gravel deposits are in hydraulic connection with a stream and where large quantities of water are pumped from nearby wells, some of the pumped water is derived from streamflow that enters the aquifer by induced infiltration. (Induced infiltration occurs when the drawdown of the water table, called the cone of depression, caused by pumping reaches the stream and creates a water table gradient sloping from the stream to the well.) Induced infiltration occurs at the village of Mannsville public water supply well.

      E. Streamflow Source Zone

      The streamflow source zone (see Figure) includes both the designated aquifer and its recharge zone extending through Jefferson, Oswego, and Lewis Counties, is the upstream headwaters area, which drains via captured runoff and stream drainage into the recharge zone. The recharge zone is the immediate area where water enters the aquifer through very permeable glacial deposits.

      F. Water Quaiity

      Chemical analyses of ground-water samples indicate that the quality of water in the Tug Hill aquifer meets State drinking-water standards.

      pH -- ranges from 5.9 to 8.0 (slightly acidic to slightly basic)
      Hardness -- ranged from 23 to 300 mg/L as CaCO 3 (soft to very hard)
      Alkalinity -- 100 mg/L, soils have a moderate capacity to neutralize acid precipitation.
      Nitrate * -- averaged 2.1 mg/L

      * Nitrate does not occur naturally in any of the rocks of this area but is a common degradation product of organic wastes. Nitrate sources include the decomposition of organic nitrogen that is introduced to the soil by nitrogen-fixing plants and bacteria, human and animal wastes, and organic and inorganic fertilizers. Thus, nitrate enters ground water from activities on the land surface or from waste-disposal systems. Nitrate levels were higher in water from the shallow wells in the unconfined parts of the aquifer than from the deeper wells in the confined aquifer.

      III. Susceptibility to Contamination

      The Northern Tug Hill Glacial Aquifer, by virtue of its geologic nature, is susceptible to contamination through several mechanisms. The aquifer is composed of highly permeable glacial sediments with low attenuation capabilities. These properties facilitate rapid and direct infiltration into the ground water zone of any surficially disposed pollutants. Contaminants entering the aquifer through direct discharge or indirectly via feeder streams, can also impact the aquifer.

      The effects of human activities on water quality in the Northern Tug Hill Glacial Aquifer are reflected primarily in the surficial (unconfined) part of the aquifer. The top of the surficial aquifer is at land surface; therefore precipitation infiltrates readily and transports contaminants from the land surface to the aquifer, whereas confined or buried aquifer are protected from surface contamination to varying degrees by filtration and layers of smaller permeability.

      The primary activity in the Northern Tug Hill Glacial Aquifer is agriculture. Most agricultural land is heavily fertilized, either with commercial fertilizer or manure, and in some areas excess nitrogen from the fertilizer is carried to the aquifer by infiltrating water in agricultural areas. Other sources of nitrogen contamination are septic systems and barnyard runoff.

      IV. Alternative Sources of Drinking Water

      Using Lake Ontario as a long range alternative to the aquifer system is a questionable option and would ultimately not be cost effective. Besides the aquifer, which could remain a plentiful source of clean water through proper planning and oversight, there are no feasible alternative sources of drinking water available which would be sufficient to supply the needs of the communities that rely on them.

      V. Summary

      Based upon the information presented, the Northern Tug Hill Glacial Aquifer meets the technical requirements for SSA designation. More than fifty percent (50%) of the drinking water for the aquifer service area is supplied by the aquifer. In addition, there are no economically feasible alternative drinking water sources which could replace the Northern Tug Hill Glacial Aquifer. It is therefore recommended that the Northern Tug Hill Glacial Aquifer be designated a SSA. Designation will provide an additional review of those projects for which Federal financial assistance is requested, and will ensure ground water protection measures, incorporating state and local measures whenever possible, are built into the projects.

      VI. Selected References

      1. Miller, T.S., Sherwood, D.A., and M.M Krebs, 1989, Hydrogeology and Water Quality of the Tug Hill Glacial Aquifer in Northern New York. Exit EPA U.S. Geological Survey Water-Resources Investigations Report 88-4014. 60 pages. 24 plates.

      2. Zarriello, P.J., 1993, Determination of the Contributing Area to Six Municipal Ground-Water Supplies in the Tug Hill Glacial Aquifer of Northern New York, With An Emphasis on the Lacona-Sandy Creek Well Field. Exit EPA U.S. Geological Survey Water-Resources Investigations Report 90-4145. 51 pages.

      VII. Tables

      Table 1. Population Served from the Northern Tug Hill Glacial Aquifer

      Source Population
      Hamlet of Adams Center 700
      Hamlet of Pierrepont Manor 163
      Village of Adams 1,624
      Village of Lacona 590
      Village of Mannsville 400
      Village of Sandy Creek 789
      Other areas 704
      TOTAL 4,970

      Table 2. Current Drinking Water Sources for the Aquifer Service Area

      Source \ Use Public
      Petitioned Aquifer 90.5 % 8.3 % 98.9 %
      Bedrock Aquifer 0.0 % 1.1 % 1.1 %
      Surface Water 0.0 % 0.0 % 0.0 %
      Transported 0.0 % 0.0 % 0.0 %
      Total 90.5 % 9.5 % 100 %


      VIII. Figures

      Figure 1.

      Northern Tug Hill Glacial Aquifer

      Figure 2. Typical Cross Section

      Typical Cross Section



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