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GLIN==> National Water-Quality Assessment reports available for the Lake Erie Basin



WRI 00-4091. OHIO, MICHIGAN, and INDIANA.


Status and Trends in Suspended-Sediment Discharges, Soil Erosion, and
Conservation Tillage in the Maumee River Basin-Ohio, Michigan, and Indiana.
By Donna N. Myers, Kevin D. Metzker, and Steven Davis, 38 pages.


Available from the Ohio District, 6480 Doubletree Ave., Columbus, Ohio
(phone 614-430-7700) or from the USGS Branch of Information Services, Box
25286, Denver, CO 80225, USGS WRIR Report 00-4091, 38 p., 14 figs.
Available on line at the URL  http://oh.water.usgs.gov/nawqa/index.html


The relation of suspended-sediment discharges to conservation-tillage
practices and soil loss were analyzed for the Maumee River Basin in Ohio,
Michigan, and Indiana as part of the U.S. Geological Survey's National
Water-Quality Assessment Program. Cropland in the basin is the largest
contributor to soil erosion and suspended-sediment discharge to the Maumee
River and the river is the largest source of suspended sediments to Lake
Erie. Retrospective and recently-collected data from 1970?98 were used to
demonstrate that increases in conservation tillage and decreases in soil
loss can be related to decreases in suspended-sediment discharge from
streams. Average annual water and suspended-sediment budgets computed for
the Maumee River Basin and its principal tributaries indicate that soil
drainage and runoff potential, stream slope, and agricultural land use are
the major human and natural factors related to suspended-sediment
discharge. Areas of poorly drained soils with high runoff potential appear
to be the major source areas of suspended sediment discharge in the Maumee
River Basin. Although conservation tillage differed in the degree of use
throughout the basin, on average, it was used on 55.4 percent of all crop
fields in the Maumee River Basin from 1993-98. The increased use of
conservation tillage was found to correspond to decreases in
suspended-sediment discharge over time at two locations in the Maumee River
Basin. A 49.8 percent decrease in suspended-sediment discharge was detected
when data from 1970?74 were compared to data from 1996?98 for the Auglaize
River near Ft. Jennings, Ohio. A decrease in suspended-sediment discharge
of 11.4 percent was detected from 1970?98 for the Maumee River at
Waterville, Ohio. No trends in streamflow at either site were detected over
the period 1970?98. The lower rate of decline in suspended-sediment
discharge for the Maumee River at Waterville, Ohio compared to the Auglaize
River near Ft. Jennings, may be due to resuspension and export of stored
sediments from drainage ditches, stream channels, and flood plains in the
large drainage basin upstream from Waterville. These findings provide
information to farmers and soil conservation agents about the ability of
conservation tillage to reduce soil erosion and suspended-sediment
discharge from the Maumee River Basin.


WRI 00-4146. MICHIGAN, OHIO, and INDIANA.


Ground-Water Quality and Vulnerability to Contamination in Selected
Agricultural Areas of Southeastern Michigan, Northwestern Ohio, and
Northeastern Indiana. By Mary Ann Thomas, 24 pages.


Copies are available from the Ohio District, 6480 Doubletree Ave.,
Columbus, Ohio, 43229 and the U.S. Geological Survey, Branch of Information
Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS WRIR
00-4106, 24 p., 10 figs., 5 tables. Available on line at the URL
http://oh.water.usgs.gov/nawqa/index.html


Available on line.


Ground-water quality was assessed in the northeastern part of the Corn
Belt, where tile-drained row crops are underlain by fractured glacial till.
Data were collected from 30 shallow monitor wells and 18 co-located
domestic wells as part of the U.S. Geological Survey's National
Water-Quality Assessment in the Lake Erie-Lake St. Clair Basin. Pesticides
or pesticide degradates were detected in 41 percent of the monitor wells
and 6 percent of the domestic wells. The pesticides detected closely
correspond to those most heavily applied?herbicides used on corn and
soybeans. Pesticide degradates were detected three times more frequently,
and at higher concentrations, than were parent compounds. No pesticide
concentration exceeded a USEPA Maximum Contaminant Level (MCL), but MCL's
have not been established for 9 of the 11 compounds detected. Thirty-seven
percent of monitor-well samples had nitrate concentrations indicative of
human influences such as fertilizer, manure or septic systems. Nitrate was
the only chemical constituent detected at a concentration greater than an
MCL. The MCL was exceeded in 7 percent of samples from monitor wells which
were too shallow to be used as a source of drinking water. Pesticide and
nitrate concentrations in the study area are low relative to other
agricultural areas of the Nation. Several authors have suggested that
ground water in parts of the Upper Midwest is minimally contaminated
because it is protected by the surficial glacial till or tile drains. These
ideas are examined in light of the relations between concentration, well
depth, and ground-water age in the study area. Most of the shallow ground
water is hydraulically connected to the land surface, based on the
observations that 83 percent of waters from monitor wells were recharged
after 1953, and 57 percent contained a pesticide or an elevated nitrate
concentration. Fractures or sand-and-gravel stringers within the till are
the probable pathways. In some areas, deeper parts of the ground-water-flow
system are also hydraulically connected to the land surface. Almost half
the waters from wells 50 to 100 feet deep were recharged after 1953.
Anthropogenic constituents were detected in samples from three domestic
wells 60 to 121 feet deep, in areas where the till is relatively
coarse-grained. The hydrogeologic system has several geochemical
characteristics conducive to transformations or sorption of nitrate or
pesticides: (1) the till is clay-rich, has a high organic-carbon content,
and contains an abundance of pyrite-rich shale fragments, (2) the ground
water has low dissolved-oxygen concentrations, and (3) iron and manganese
oxides and oxyhyroxides line the faces of fractures in the unsaturated
zone. Although the aquifer system appears be protected from contamination
in some areas, the fact that the surficial till is heterogeneous and of
variable thickness suggests that the protection is not uniform. The
protection can be breached by fractures or sand-and-gravel stringers, which
are apparent in core samples but not noted on domestic-well logs.

Donna N. Myers
U.S. Geological Survey
6480 Doubletree Ave.
Columbus, Ohio 43229-1111
614/430-7715
dnmyers@usgs.gov


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