Executive Summary
Eight sampling trips were coordinated after engineered levee breaches hydrologically
reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. The
reconnection, by a series of explosive blasts, was coordinated by The Nature Conservancy to
reclaim wetlands that had for approximately seven decades been leveed for crop production.
Sets of nonmetallic porewater profilers (U.S. Patent 8,051,727 B1; November 8, 2011; http://www.uspto.gov/web/patents/patog/ week45/OG/html/1372-2/US08051727-20111108.html.)
were deployed during these trips in November 2007, June 2008, May 2009, July 2009, May
2010, August 2010, June 2011, and July 2011 (table 1). Deployments temporally spanned the
annual cyanophyte bloom of Aphanizomenon flos–aquae and spatially involved three lake and
four wetland sites. Spatial and temporal variation in solute benthic flux was determined by the
field team, using the profilers, over an approximately 4-year period beginning 3 days after the
levee breaches. The highest flux to the water column of dissolved organic carbon (DOC) was
detected in the newly flooded wetland, contrasting negative or insignificant DOC fluxes at
adjacent lake sites. Over the multiyear study, DOC benthic fluxes dissipated in the reconnected
wetlands, converging to values similar to those for established wetlands and to the adjacent lake
(table 2). In contrast to DOC, benthic sources of soluble reactive phosphorus, ammonium,
dissolved iron and manganese from within the reconnected wetlands were consistently elevated
(that is, significant in magnitude relative to riverine and established-wetland sources) indicating
a multi-year time scale for certain chemical changes after the levee breaches (table 2).
Colonization of the reconnected wetlands by aquatic benthic invertebrates during the study
trended toward the assemblages in established wetlands, providing further evidence of a multiyear
transition of this area to permanent aquatic habitat (table 3).
Both the lake and wetland benthic environments substantively contribute to macro- and
micronutrients in the water column. Wetland areas undergoing restoration, and those being used
for water storage, function very differently relatively to the established wetland within the Upper
Klamath Lake National Wildlife Refuge, adjacent Upper Klamath Lake. Developing long-term
management strategies for water quality in the Upper Klamath Basin requires recognition of the
multi-year time scales associated with restoring wetlands that provide natural, seasonal
ecosystem function and services.
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First posted March 29, 2012
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