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Maquoketa River Watershed, Iowa
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As part of the National Pilot Project
funded by EPA, TIAER undertook a watershed study of
the upper Maquoketa River watershed in Iowa. Collaborating
agencies for this study included the Center
for Agricultural and Rural Development (CARD), Iowa
Extension Service, Iowa
State University Agricultural Engineering Department,
and the Iowa
Department of Natural Resources. The goal of the
NPP is to identify technologies, policies, and institutional
settings that can reduce potential environmental impacts
of livestock production. At the same time, the NPP strives
to recognize options that allow the livestock industry
to remain competitive in increasingly open world markets.
Problems
The upper Maquoketa River watershed (UMRW) is a 40,200
acre drainage area that forms a portion of the Maquoketa
River Basin. Located in northeastern Iowa, the UMRW
contains two distinct topographic areas. The perimeter
consists of gently rolling cropland. Toward the interior,
the terrain gradually changes as one moves closer to
the Maquoketa River. Gullies and stream banks are steeper,
and soils are more susceptible to erosion.
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Livestock production in the UMRW
is extensive and diverse. Swine, dairy and beef cattle
operations are common. Of the 219 farmsteads in the
watershed, 89 produce some type of livestock. Some operations
have two or three types of animals. Almost all livestock
producers in the watershed grow crops for on-farm use
and for sale. A typical farm with livestock grows about
200 acres of corn and 120 acres of soybeans. Most dairy
and cattle farmers grow alfalfa for use as feed. Conventional
tillage methods are preferred in the UMRW and fertilizer
use is characteristic of other areas in Iowa. Most fertilizer
is applied on cornfields at an average of 130 to 160
pounds of nitrogen per acre.
Fishing and agriculture are both
important in this part of Iowa, but sediment, nitrogen,
and phosphorus were the key nutrients affecting water
quality. Nonpoint source water pollutants from agricultural
production—primarily sediment and nutrients—appeared
to affect surface waters of the UMRW. Surface runoff
and tile drain flows from manure and fertilizer application
fields and animal processing areas in the UMRW are likely
sources of elevated levels of nutrients in the Maquoketa
River. Sediment runoff caused by erosion is also a major
concern.
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Objectives
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The goal of the study was to identify
best management practices that would have the greatest
positive impact on water quality and their economic
impacts. Stakeholders in the watershed, including producers,
formed an objective to achieve a 50 percent reduction
in pollutants, requiring producers to adopt and implement
combinations of practices.
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Methods
 TIAER
and its partners used water
quality monitoring and the CEEOT computer modeling framework
to evaluate the watershed. Several categories of farms are
included in CEEOT-LP’s baseline for the UMRW. Three major
types of livestock species were modeled—swine, dairy, and
beef cattle. Swine producers operate either open lot facilities
or large confinement units. Dairies are freestall barns or
tie stall barns with open lots. Various types of operations
raise beef cattle on open lots or pasture. These include cow-calf,
feeder cattle, and calf and heifer operations. Three types
of crop rotations were assumed–continuous corn, corn-corn-oats-alfalfa-alfalfa,
and corn-soybean. Dairy and cattle producers devote a percentage
of their acreage to pasture. Dairy, cattle, small hog producers,
and operations with several types of livestock manage solid
manure; large hog confinement operations manage liquid manure
only. Other major assumptions of the baseline concern manure
handling and application, cropping practices, and fertilizer
application rates.
Table
1 lists and describes the 17 individual policy scenarios
and 4 combination scenarios that were simulated in the Maquoketa.
The scenarios either alter farm management practices or propose
structural modifications. The scenarios include changes in
the rate, timing, and mode of manure applications, commercial
fertilizer use, cropland tillage, soil management, swine ration
modifications, structural BMPs, and alternative production
systems. Some of the scenarios assume that farmers develop
and maintain nutrient management plans.
Each policy was analyzed to estimate financial
impacts on local producers in the UMRW and, at the same time,
nutrient and sediment loads and concentrations in surface
waters in the UMRW were evaluated. Environmental impact analysis
was conducted using the water quality models Soil and Water
Assessment Tool (SWAT) and Agricultural Policy/Environmental
eXtender (APEX). Economic impacts of all scenarios effects
were evaluated at both the farm and regional level. The farm
economic model (FEM) of CEEOT was developed by TIAER in conjunction
with CARD. Regional effects were estimated with the IMPLAN
model.
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