U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 033-99

September 1999

New York

New York City’s Water Supply

New York City’s water-supply

system provides water to about 40

percent of the State’s 18.1 million

people. The U.S. Geological Survey

(USGS) has worked with the New

York City Department of Environmental Protection (NYCDEP) for

many years to monitor and assess

the City’s water resources and

provide information for effective

resource management.

The USGS is investigating the

effects of forest-harvesting techniques on nitrogen cycling in the

Neversink watershed in the Catskill

Mountains. The Neversink River

feeds the Neversink Reservoir, a

major water source for New York

City. The Catskill region receives

large amounts of acid rain, which

can acidify surface waters and

release aluminum, which can be

toxic to fish. Nitrogen in forest soils

in excess of biological demands

results in soil water and surface-water

acidification by nitric acid. The

project aims to demonstrate whether

or not forest-harvesting practices can

moderate stream-water acidification.

A recent USGS-NYCDEP project in

the Croton River watershed examined

the effects of suburban development

on the chemical quality of ground

water that discharges to local streams.

These streams feed the Croton

Reservoir system, which provides 10

to 15 percent of New York City’s

water supply. The concentrations of

some constituents were found to

increase with an increase in suburban

development. Increased chloride and

nitrate concentrations were identified

as indicators of unsewered suburban

development.

The USGS and NYCDEP are monitoring ground-water levels and water

quality in Brooklyn and Queens

because ground water in these

locations might be used to supplement the City’s reservoir system

during drought. During 1992–96,

water levels were measured monthly

at 88 wells, and 240 water samples

were collected and analyzed for an

extensive list of chemicals. This

monitoring is continuing. A computer-based model of ground-water

flow in the aquifer system was

developed to simulate proposed

ground-water withdrawals so that the

effects on ground-water levels and

saltwater intrusion can be predicted.

The NYCDEP is constructing new

water-supply tunnels in the bedrock

beneath the City, where water-bearing

fractures can cause costly and hazardous problems. Information obtained

from drilling and coring does not

adequately describe either the

ground-water conditions in the

bedrock along the proposed route of

the tunnel or other geologic features

such as faults, which can cause

construction problems. The USGS is

integrating several new, advanced

borehole geophysical methods to

investigate ground-water flow in

fractured bedrock. Recently, the

USGS and NYCDEP began a cooperative effort to apply these methods

to characterize waterbearing fractures

and other geologic features that will

be encountered during tunnel construction. This should enable safer

and more efficient construction and

expand our knowledge of the geology

in the area.

Pesticides

Improved analytical capability

developed in USGS laboratories

detects pesticides at concentrations

much lower than regulatory limits and

allows the USGS to observe the

transport and fate of pesticides after

they are applied. The USGS, in

cooperation with the New York State

Department of Environmental Conservation (NYSDEC), has surveyed

the occurrence of pesticides (both

herbicides and insecticides) in

streams and rivers across the State

and in ground water on Long Island.

Herbicides were detected most

frequently in streams draining

watersheds with significant agricultural use, and insecticides were

detected most frequently in streams

draining watersheds that are urbanized or that contain extensive areas of

Figure 1. New York City water-supply

system.

Croton

Watershed

Croton

Reservoir

Neversink

Reservoir

Neversink

Watershed

Catskill Mountains

NEW YORK

PENNSYLVANIA

CONNECTICUT

MASS

Long Island Sound

Atlantic Ocean

Brooklyn

Queens

West Delaware Tunnel

East Delaware Tunnel

Shandaken

Tunnel

Delaware Aqueduct

NEW JERSEY

Hudson River NEW

YORK

Location

Map

Study Area

NEW YORK

42°

41°

75° 74°

0 10 20 30 MILES

0 10 20 30 KILOMETER
science for a changing world

vineyards or orchards. Concentrations

of most pesticides detected were low,

generally not exceeding 0.1 part per

billion. Continuing work is examining pesticide occurrence in some of

the Finger Lakes, in the sole source

aquifer system on Long Island, in

public water-supply sources, and in

ground water.

New York Harbor

Sediment accumulation obstructs

New York Harbor and causes economic losses. Some of the sediment is

contaminated with heavy metals,

PCB’s, and other organic compounds,

and the contamination makes the

disposal of dredged material a

concern. Planning for the safe disposal of the contaminated, dredged

material requires identification of

which sediments deposited within the

harbor are contaminated and evaluations of disposal sites.

The USGS is studying this region to

identify sediments on the sea floor,

map the distribution of contaminants

in the sediment, and develop a

predictive capability for the long-term

transport and fate of sediments and

contaminants. A regional understanding of the sea floor geology, topography, and dynamics of these coastal

sediments is needed for management

and use of the nearshore environment

and to plan further studies.

Previous work by the USGS has

shown that Hudson River tributaries

supply differing amounts of sediment

depending on flow conditions and on

land use in their basins. The USGS is

helping NYSDEC to identify sources

of contaminants flowing into New

York Harbor by operating four

monitoring sites in the Hudson River

basin. At these sites, sediment transport is measured and sediment

samples are collected for contaminant

analysis.

Lake Ontario

In April 1998, USGS scientists

caught a deepwater sculpin in southwestern Lake Ontario by towing a

trawl net along the lake floor 492 feet

below the surface from the USGS

Research Vessel KAHO. Deepwater

sculpin had not been captured in the

U.S. waters of Lake Ontario since

1942, and only six deepwater sculpin

have been reported in Canadian

waters since 1972. Deepwater sculpin

were plentiful in Lake Ontario in the

early 1900’s, but their numbers

plummeted in the 1950’s, probably

through predation on the sculpin

young by alewife, a nonnative fish

that invaded Lake Ontario from the

Atlantic Ocean. Deepwater sculpins

are an important link in the offshore

food chain, eating bottom-dwelling

invertebrates and, in turn, being eaten

by lake trout, historically the lake’s

top predator. The reappearance of

deepwater sculpin in U.S. waters of

Lake Ontario is one of many recent

signs of recovery of the lake’s native

fish community. Other signs are that

Figure 2. Map of the area offshore of the New York-New Jersey metropolitan

region showing topographic features on the sea floor (gray scale), dumpsites

(areas enclosed by yellow lines), lead concentrations in surface sediments

(colored dots), and subsurface accumulation of lead (profiles with

concentrations elevated above background values in red). The highest

concentrations of lead (and other contaminants) are in the upper Hudson Shelf

Valley and extend as far as 80 km downvalley from the original dumpsite.

NEW

JERSEY

LONG ISLAND

40°N

40.5°N

73.5°W

73°W74°W

47 to 218 (Effects Range-Medium)

35 to 47 (Effects Range-Low)

25 to 35 (soil)

1 to 25 (nat. background)

Lead concentration in surface

sediment of New York Bight,

in micrograms per gram

HUDSON SHELF VALLEY

2 0

Kilometers

0 10
New York

the numbers of two other formerly

abundant native fishes—burbot and

emerald shiner—are increasing in

survey catches and hatchery lake

trout are successfully reproducing

after more than a decade of failure.

Growing populations of the doublecrested cormorant in the eastern basin

of Lake Ontario have caused concern

among natural-resource managers and

the public because cormorants eat

fish, including game fish. Many

worry that an overabundance of the

birds will adversely affect fish

populations and change the ecology

of the lake. USGS scientists have

been studying cormorants in Lake

Ontario since 1993. Early investigations showed that most predation of

stocked salmon and trout occurred

within the first 24 hours after stocking and that about 11 percent of the

stocked fish were eaten by cormorants within 4 days. Subsequent

research revealed that predation can

be significantly reduced when fish are

either stocked at night or released

offshore. These results have led the

NYSDEC to modify its salmonid

stocking strategy, thereby increasing

the survival of stocked fish.

Mapping

Color-infrared digital orthophoto

quadrangles are available for about

80 percent of New York. When

completed, this statewide project,

funded by six Federal and State

agencies [the NYSDEC, the National

Park Service, the Natural Resources

Conservation Service, the U.S.

Environmental Protection Agency

(EPA), the Farm Services Agency,

and the USGS], will provide data

users with the first standardized,

large-scale image base for the entire

State. In addition, the NYSDEC, in

cooperation with the USGS, produced

a statewide coverage of digital

elevation model data with 10-meter

resolution. Both datasets are important for visualizing the terrain and the

human impact on that terrain. Uses

for these data include delineating

flood plains, planning for emergencies such as floods, developing soil

conservation techniques, identifying

and remedying nonpoint-source

pollution, and revising maps.

The USGS is collecting data on urban

areas and transportation during the

20th century in the New York City

metropolitan area to provide a

visualization of settlement patterns

through time. These data can be used

to predict future growth in the

metropolitan area. This can lead to

improved planning and policymaking

regarding resource availability,

resource exploitation, and conservation strategies in response to a

growing investment in urban roads,

water supply, sewer systems, and

other utilities. The USGS is coordinating this project with Cornell

University, the Regional Planning

Authorities, and the EPA.

The USGS and the New York State

Department of Transportation

(NYSDOT) are studying the feasibility of a cooperative effort to produce

single edition, 1:24,000-scale, 7.5-

minute quadrangle maps, which both

organizations now produce independently. Production processes and

standards are being examined for

similarities and differences between

the two map series. If test results are

satisfactory, both agencies would

distribute the same map product, thus

minimizing production and distribution costs while freeing resources and

capabilities to revise the 1:24,000-

scale maps within the State.

Tidal Scour at a State Highway

Bridge

In the summer of 1998, USGS

expertise in stream processes and

bridge scour was put to use in an

unusual setting at a narrow marine

channel where the potential for tidal

scour is high. Scour is the erosive

action of flowing water that removes

material from the stream or channel

bed. Previous depth surveys of the

Sloop Channel Bridge along the

southern shore of Nassau County

suggested that some scouring had

taken place, but due to insufficient

resolution and density of data, and the

possibility of infilling of scourholes, a

more precise geophysical survey was

needed. The public safety issue

prompted the USGS, in cooperation

with the NYSDOT, to quickly

mobilize research-grade instrumentation resources from New York,

Connecticut, and Kentucky to conduct a marine geophysical survey at

the Sloop Channel Bridge to delineate

the extent of tidal scour.

Two large scour holes along the

eastern and western sides of the

bridge were identified. These scour

holes extended to more than 47 feet

below sea level and partly beneath the

bridge—much deeper and farther

beyond the bridge than had been

mapped previously. Several bathymetric profiles depicted scour holes

that have developed around several

Figure 3. Deepwater sculpin.

15

30

45

60

SEA

LEVEL

East

FEET

West

DEPTH, IN FEET BELOW WATER SURFACE

Approximate

depth of pilings

Bridge piers

Vertical exaggeration x10

Clay Sand and silt Clay

Scour Scour hole hole

Bridge

Figure 4. Section from seismic

reflection profile at bridge at Sloop

Channel.
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piers under the bridge. An evaluation

of flow velocities under the bridge

showed that the bridge piers create a

flume effect that increases water

velocities and enhances scour.

As a result of this study, the

NYSDOT and Federal Highway

Administration have begun to

reevaluate the manner in which

bridges are inspected and surveyed

for tidal scouring in southeastern

New York State. Shortly after the

geophysical survey of Sloop Channel

Bridge, the NYSDOT decided to

demolish Sloop Channel Bridge and

build a new structure in its place.

Wetlands

The use of wetlands to reduce peak

stormwater flows and to treat

stormwater and landfill leachate is

increasing, but their effectiveness is

yet to be demonstrated in many

settings. The USGS is assessing the

effectiveness of natural and artificial

wetlands as passive, inexpensive

methods of stormwater and leachate

treatment in New York State.

Two USGS studies in cooperation

with the New York State Energy

Research and Development Authority

evaluated treatment of landfill

leachate. In Tompkins County, four

types of treatments were evaluated,

and use of a mixed bed of sand and

gravel was found to be most effective. A subsequent test of design

improvements in Monroe County (a

ponded pretreatment wetland and a

subsurface-flow gravel bed) showed

that increased leachate detention

times and the addition of passive

baffles that increased mixing within

the wetland further improved treatment efficiencies.

Ongoing USGS work includes studies

with Monroe County to evaluate the

use of the floodplain wetland at the

mouth of Irondequoit Creek near

Rochester as a nutrient and sediment

filter to improve the water quality of

Irondequoit Bay and the effects of

stormwater detention in a mature and

diversely vegetated constructed

wetland on water quality and temperature. Also, a study with the

Natural Resources Conservation

Service is evaluating the effects of a

constructed nutrient- and sedimentcontrol system to treat runoff from a

cattle pasture in Cayuga County. The

studies with Monroe County have

documented the effectiveness of

constructed and natural wetlands in

significantly reducing the loads of

phosphorus and suspended solids in

storm runoff. Small, but significant,

reductions in nitrogen loads also have

been measured in the natural wetland.

One concern addressed in the created

wetland study was that a wetland

used to treat runoff from a residential

The USGS has 139

employees in New York

Cortland Ithaca

Syracuse

Oswego

Potsdam

Coram

Troy

development could cause water

temperatures to increase and adversely affect fish habitat. Study

results showed that these concerns

were unfounded. Outflow temperatures were 2-5 degrees Fahrenheit

lower than inflow temperatures

during most of the year. During the

late spring and early summer, when

outflow temperatures were close to or

slightly above the inflow temperatures, the detention of flows in the

wetland caused a slower release of

water to the receiving water body

than would have occurred otherwise.

Figure 5. Contaminant removal

processes in a constructed wetland.

BIOLOGICAL Treated Water

CHEMICAL

PHYSICAL

INFLUENT

Plants take up and 

transfer oxygen 

to the root zone