JAWRA - Ag Conservation

• Project Type: General OWC
• Title: Designing Impact Assessments for Evaluating Ecological Effects of Agricultural Conservation Practices on Streams
• Date: 12/15/2009
• Water Conservation - Doc Type: Reports

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DESIGNING IMPACT ASSESSMENTS FOR EVALUATING ECOLOGICAL EFFECTS
OF AGRICULTURAL CONSERVATION PRACTICES ON STREAMS'
Peter C. Smiley Jr., F. Douglas Shields Jr., and Scott S. Knight
ABSTRACT: Conservation practices are regularly implemented within agricultural watersheds throughout the
United States without evaluating their ecological impacts. Impact assessments documenting how habitat and
aquatic biota within streams respond to these practices are needed for evaluating the effects of conservation
practices. Numerous sampling protocols have been developed for monitoring streams. However, protocols
designed for monitoring studies are not appropriate for impact assessments. We developed guiding principles for
designing impact assessments of ecological responses to conservation practices. The guiding principles are as fol-
lows: (1) develop the hypothesis first, (2) use replicated experimental designs having controls and treatments,
(3) assess the habitat and biological characteristics with quantitative and repeatable sampling methods, (4) use
multiple sampling techniques for collecting aquatic organisms, and (5) standardize sampling efforts for aquatic
organisms. The guiding principles were applied in designing a study intended to evaluate the influence of herba-
ceous riparian buffers on channelized headwater streams in central Ohio. Our example highlights that the
application of our recommendations will result in impact assessments that are hypothesis- driven and incorpo-
rate quantitative methods for the measurement of abiotic and biotic attributes.
(KEY TERMS: agricultural streams; conservation practices; environmental impacts; experimental design; envi-
ronmental sampling; aquatic ecology; Conservation Effects Assessment Project.)
Smiley, Peter C., Jr., F. Douglas Shields Jr., and Scott S. Knight, 2009. Designing Impact Assessments for Eval-
uating Ecological Effects of Agricultural Conservation Practices on Streams. Journal of the American Water
Resources Association (JAWRA) 45(4):867 -878. DOI: 10 .1111/j.1752- 1688.2009.00330.x
INTRODUCTION
Conservation practices were traditionally defined
as methods for managing soil and water resources to
improve agricultural production, but the current defi-
nition includes methods to reduce the environmental
impacts of agriculture on terrestrial and aquatic eco-
systems (Soil and Water Conservation Society, 2001).
Specifically, conservation practices are land, water,
and agronomic management practices designed to
reduce erosion rates, improve water quality, and
restore terrestrial and aquatic habitats in agricul-
tural streams. Conservation tillage, riparian buffers,
and wetland creation are just a few examples of prac-
tices that have been promoted and funded through
various federal and state programs. Conservation
practices have been regularly implemented within
'Paper No. JAWRA -08- 0036 -P of the Journal of the American Water Resources Association ( JAWRA). Received February 21, 2008;
accepted January 27, 2009. © 2009 American Water Resources Association. No claim to original U.S. government works. Discussions are
open until six months from print publication.
2 Respectively, Research Ecologist (Smiley), USDA -ARS, Soil Drainage Research Unit, 590 Woody Hayes Drive, Columbus, Ohio 43210;
Research Hydraulic Engineer (Shields) and Research Ecologist (Knight), USDA -ARS, National Sedimentation Laboratory, P.O. Box 1157,
Oxford, Mississippi 38655 (E- Mail/Smiley: [e-mail]).
JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 867
JAWRA