Development of ground water for irrigation affects streamflow and water
levels in the sand-plain area of central Wisconsin. Additional irrigation
development may reduce opportunities for water-based recreation by degrading
the streams as trout habitat and by lowering lake levels. This study was
made to inventory present development of irrigation in the sand-plain area,
assess potential future development, and estimate the effects of irrigation
on streamflow and ground-water levels.
The suitability of land and the availability of ground water for
irrigation are dependent, to a large extent, upon the geology of the area.
Rocks making up the ground-water reservoir include outwash, morainal deposits,
and glacial lake deposits. These deposits are underlain by crystalline
rocks and by sandstone, which act as the floor of the ground-water reservoir.
Outwash, the main aquifer, supplies water to about 300 irrigation wells
and maintains relatively stable flow in the streams draining the area. The
saturated thickness of these deposits is more than 100 feet over much of the
area and is as much as 180 feet in bedrock valleys. The saturated thickness
of the outwash generally is great enough to provide sufficient water for
large-scale irrigation in all but two areas --one near the town of Wisconsin
Rapids and one near Dorro Couche Mound. Aquifer tests indicate that the
permeability of the outwash is quite high, ranging from about 1,000 gpd per
square foot to about 3,800 gpd per square foot, Specific capacities of
irrigation wells in the area range from 14 to 157 gpm per foot of drawdown.
Water use in the sand-plain area is mainly for irrigation and waterbased
recreation. Irrigation development began in the area in the late
1940's, and by 1967 about 19,500 acre-feet of water were pumped to irrigate
34,000 acres of potatoes, snap beans, corn, cucumbers, and other crops.
About 70 percent of the applied water was lost to evapotranspiration, and
about 30 percent was returned to the ground-water reservoir. Irrigation
development should continue in the sand plain; future development probably
will include improved artificial drainage and land clearing.
The hydrology of the sand-plain area was studied from water budgets for
seven basins and from water balances for eight types of vegetative cover or
land use. During the study period about 16-20 inches of the 28- to 30-inch
average annual precipitation were lost to evapotranspiration from different
basins in the area, Evapotranspiration from different types of vegetative
cover or land use ranged from about 14 inches per year for bare ground to
about 25 inches per year from land covered by phreatophytes. Evapotranspiration
is about 19 inches from forested land, about 16 inches from grassland
and unirrigated row crops, about 19 inches from irrigated beans, and
about 22 inches from irrigated potatoes.
Variations in evapotranspiration from the different types of vegetative
cover result mainly from differences in soil moisture available to the plants.
Available soil moisture ranges from about 1 inch for shallow-rooted grasses
and row crops to about 3 inches for forest.
Most of the precipitation not used by plants or to replenish soil moisture
seeps to the water table, and ground-water recharge in the area averages
about 12-14 inches per year. However, computed recharge ranged from about
3 inches to about 22 inches during the 1948-67 period, depending upon the
amount and seasonal distribution of precipitation. Of the average 12-14
inches of recharge, about lo-13 inches are discharged to the streams draining
the area, and about l-2 inches are used by phreatophytes or by irrigated
Annual streamflow in the area averages about 11-12 inches per year, and
because it is sustained mainly by ground water, its seasonal distribution is
fairly uniform, However, streamflow varies seasonally, being highest in the
spring, low in the summer, higher
Additional publication details
USGS Numbered Series
Effects of Irrigation on Streamflow in the Central Sand Plain of Wisconsin