Currently browsing tag

stream restoration

After the dam comes down: groundwater-stream interactions and water quality effects of restored and unrestored reaches in northeastern Ohio

The Watershed Hydrology lab will be out in force for the Geological Society of America annual meeting in Vancouver in October. For the last few days, we’ve been sharing the abstracts of the work we are presenting there.

AFTER THE DAM COMES DOWN: GROUNDWATER-STREAM INTERACTIONS AND WATER QUALITY EFFECTS OF RESTORED AND UNRESTORED REACHES IN NORTHEASTERN OHIO

BROWN, Krista Marie, Geology, Kent State University, Kent, OH 44240, kbooth@kent.edu and JEFFERSON, Anne J., Department of Geology, Kent State University, 221 McGilvrey Hall, Kent, OH 44240

Over that past decade, dam removals have become increasingly popular, as many dams near the end of their life expectancy. With an anticipated increase of dam removals in coming years, this study aims to develop an understanding of groundwater-stream interactions and water quality in former reservoirs after dam removal. Low head dams were removed in 2009 on Plum Creek and Kelsey Creek, tributaries to the Cuyahoga River. Kelsey Creek reservoir remains unaltered and consists of a stream channel flowing through riparian-wetland environments, while Plum Creek reservoir underwent channel restoration in 2011. At Kelsey Creek, 20 piezometers and 3 wells were installed within the former reservoir. Since October 2013, hydraulic heads have been recorded semi-weekly for aquifer modeling and water samples have been taken in the wells and stream. Water quality is being evaluated with field-measured parameters and ion chromatography. Plum Creek is being used to understand the water quality effects of channel restoration.
At Kelsey Creek, interaction between the stream and shallow groundwater is evident. The stream tends to contribute shallow groundwater flow toward the western side of the site and north, parallel to the stream. The well closest to the stream shows variability in specific conductance, indicating bidirectional groundwater-stream exchange and all wells show rapid response to precipitation events. Hydraulic conductivity calculated using the Hvorslev method ranged 2.84×10-2to 7.38×10-6 m/s and poorly correlate with the bulk sediments in Kelsey Creek.
Despite the wetland and groundwater-stream exchange in the unrestored Kelsey Creek, there is little change in stream water quality within the former reservoir site, similar to the restored Plum Creek site. This suggests that there is little water quality benefit to be gained from stream restoration at dam removal sites. Left unaltered, Kelsey Creek provides flood control and groundwater recharge in wetland areas.

Changes in hyporheic exchange and subsurface processes following stream restoration

The Watershed Hydrology lab will be out in force for the Geological Society of America annual meeting in Vancouver in October. Over the next few days, we’ll be sharing the abstracts of the work we are presenting there.

CHANGES IN HYPORHEIC EXCHANGE AND SUBSURFACE PROCESSES FOLLOWING STREAM RESTORATION

BAKER, Stuart B., Department of Geology, Kent State University, 221 McGilvrey Hall, 325 S. Lincoln St, Kent, OH 44242, sbaker51@kent.edu and JEFFERSON, Anne J., Department of Geology, Kent State University, 221 McGilvrey Hall, Kent, OH 44240
Stream restoration is a billion dollar industry with major goals of improving water quality and degraded habitat, yet restoration often falls short of significant improvements in toward these objectives. At present, there are limited data and understanding of the physical and biogeochemical responses to restoration that constrain the potential for water quality and ecological improvements. Hyporheic exchange, the flow of water into and out of the streambed, is an important stream process that serves a critical role in naturally functioning streams, allowing for stream water to interact with the substrate in various processes. Hyporheic flowpaths can be altered by the transport of fine sediment through the stream bed and are thus susceptible to changes in sediment regime and hydraulics, as well as the changes wrought by construction of a restoration project. The goal of this research is to determine the effect of restoration on hyporheic exchange and associated biogeochemical processes. Preliminary results from Kelsey Creek, OH, a second-order stream restored in August 2013, show a slight decrease in average hydraulic conductivity but an increase in heterogeneity from pre-restoration (geometric mean 8.47×10-5 m/s, range 2.67×10-5-3.05×10-4) to four months post-restoration (geometric mean 4.40×10-5 m/s, range 1.18×10-6-1.19×10-3) to ten months post-restoration (geometric mean 1.41×10-5 m/s, range 1.11×10-6-6.40×10-4) in piezometer nests through large constructed riffle structures. These piezometers also indicate dominance of downwelling throughout riffle structures with only isolated locations of upwelling. A stream in Holden Arboretum, OH restored in April 2014 had no significant change in average hydraulic conductivity between 1 and 2 months post-restoration, but many individual piezometers had increases of over 100% or decreases of over 50%. The greater variation in hydraulic conductivities in both restored streams may be adjustment from disturbance to a new dynamic equilibrium. Transient storage and hyporheic exchange were also measured with resazurin injections pre-restoration and post-restoration, and nutrient injections of NH4Cl will compare the nitrogen uptake rates of the restored reach to an unrestored reach downstream.

Research Experience for Undergraduates focused on Stream Restoration

Collaborator Jason Vogel at Oklahoma State asked me to spread the word about their cool new REU on stream restoration, starting this summer. Application deadlines are February 15th and the program runs May 26 – July 31st. For more information: http://studentwater.okstate.edu/content/nsf-reu-streams

A Research Experience for Undergraduates (REU) Site will provide seven undergraduate students a research experience over a ten week period during the summers of 2015-2017. The research will include studies in hydrology, geosciences, and biology at the Cow Creek Stream Rehabilitation Site on the Oklahoma State University (OSU) campus. The opportunity to study streams at a site on a University campus recently rehabilitated is unique. The central theme of the program will be discussing ways to rehabilitate streams, and specifically evaluating natural channel design approaches through process-based investigations. Billions of dollars are spent annually on stream rehabilitation across the United States. Many current stream rehabilitation projects use natural channel design concepts, which are often criticized. The alternative is a complex, process-based analysis of the dynamic system and impact of stream modifications on the hydraulics, sediment transport, and biological community. This proposal hypothesizes that future restoration approaches will most likely resemble a morphed combination of natural channel design and process-based techniques. Students will participate in research projects quantifying the role of vegetation on streambank erosion, documenting the influence of in-stream structures on retention in the stream, evaluating the effect of sediment on fish, using aquatic macroinvertebrates to assess streambank modifications, evaluating plant diversity response, and studying vegetation impacts on stream temperature.

Upper Midwest Stream Restoration Symposium

I participated in this a few years ago and it was a great experience for practitioners, regulators, and academics of stream restoration.

Let me encourage you to submit an abstract to the 2015 Upper Midwest Stream Restoration Symposium (UMSRS) to be held Feb 8-11, 2015 in Dubuque, Iowa. Organized by the regional Partnership for River Restoration and Science in the Upper Midwest (PRRSUM), the UMSRS focuses on bringing together researchers and applied practitioners to advance the dialogue of river and stream restoration in the Midwest.

The oral abstract deadline for the conference is September 26, 2014. Learn more in the attached flyer and PRRSUM brochure. If you are unable to participate, please consider signing up for our mailing list to learn about other PRRSUM activities (only 1-2 emails a month!) at www.prrsum.org.

For more information: http://www.prrsum.org/

Development of hyporheic exchange and nutrient uptake following stream restoration

Next week, the Watershed Hydrology Lab will be well represented at the CUAHSI 2014 Biennial Colloquium. We’ll be presenting four posters, so here come the abstracts…

Development of hyporheic exchange and nutrient uptake following stream restoration

Stuart Baker and Anne Jefferson

Stream restoration is a multi-million dollar industry in Ohio, with major goals of improving water quality and degraded habitat. Yet restoration often falls short of significant improvements in water quality and biodiversity. It is thus important to improve the theory and practice of stream restoration in order to achieve greater benefits per dollar spent, yet there are limited data and understanding of the physical and biogeochemical responses to restoration that constrain the potential for water quality and ecological improvements. Hyporheic exchange, the flow of water into and out of the streambed, is an important stream process that serves critical roles in naturally functioning streams, allowing for stream water to participate with the substrate in various processes. Hyporheic flowpaths can be altered by the transport of fine sediment through the stream bed and are thus susceptible to changes in sediment regime and hydraulics, as well as the changes wrought by construction of a restoration project. The goal of this research is to determine the effectiveness of restoration in enhancing hyporheic flow and associated biogeochemical processes to improve water quality. Preliminary results from Kelsey Creek, OH, a second-order stream restored in August 2013, show a decrease in average hydraulic conductivity but an increase in heterogeneity from pre-restoration (geometric mean 8.47×10-5 m/s, range 1.18×10-6-1.19×10-3) to post-restoration (geometric mean 4.41×10-5 m/s, range 2.67×10-5-3.05×10-4) in piezometer nests through large constructed riffle structures. These piezometers also indicate dominance of downwelling throughout riffle structures with only isolated locations of upwelling. Transient storage and hyporheic exchange will be measured with resazurin injections for comparison between pre-restoration and post-restoration, and nutrient injections of NH4Cl at time points following the restoration will compare the nitrogen uptake rates of the restored reach to an unrestored reach downstream. Additional sites are planned for study to include restoration projects of different ages to examine the development of hyporheic exchange and biogeochemistry after completion of restoration projects.

Mackenzie Osypian defends her thesis on stream restoration and transient storage

Woman in stream with PVC pipes (piezometers)

Mackenzie tending to piezometers in one of her streams.

Mackenzie Osypian is defending her MS research in Civil Engineering at UNC Charlotte, April 22nd at 4:00 pm in McEniry Hall 441 on the UNC Charlotte campus. Mackenzie is advised by Anne Jefferson and Sandra Clinton. John Daniels and Jim Bowen are on her committee.

Mackenzie’s research is titled: “Evaluating restoration effects on transient storage and hyporheic exchange in urban and forested streams.”  Her abstract is below:

Millions of dollars are spent each year on restoration projects designed to improve stream habitat, but few studies have investigated effects of restoration on groundwater- surface water interactions. Hyporheic exchange and transient storage in four second-order streams (urban/forest; restored/unrestored) were studied by measuring geomorphology, streambed vertical head gradients and water fluxes, and by using conservative, impulse-loaded tracer studies along with the OTIS model. Total storage exchange and percent hyporheic exchange were found by utilizing the OTIS P parameters and the sum of downwelling fluxes calculated in SURFER. The upwelling and downwelling varied between -1.783 m/m to 3.760 m/m in the restored urban stream, which contains large step structures, while the unrestored urban stream had no measured upwelling or downwelling (0 m/m) along the reach, which is incised to bedrock.  The forested restored stream had a smaller range of hydraulic gradients (-0.012 m/m to 1.99 m/m) compared to the forested unrestored stream, which ranged from -0.725 m/m to 0.610 m/m. The forested unrestored reach had the highest percent of hyporheic exchange, reaching 22% during the winter season. The urban restored has the smallest percent of hyporheic exchange of 0% across all seasons due to the exposure of bedrock in the streambed. The restored reaches were found to have between 0% and 6% of total transient storage exchange occurring in the hyporheic zones, with some seasonal variability.

The results indicate that restoration increases the hyporheic storage when the stream has incised to bedrock, but that large in-channel storage is also created. When the stream has an alluvial bed (as in the forested streams), the percent of hyporheic flow compared to total storage is reduced. The forested unrestored stream had the largest average hydraulic conductivity of 0.006 cm/s compared to the forested restored, 0.001 cm/s, and the urban restored, 0.001 cm/s.  The restored forested site had a maximum area to storage area ratio of 247 m2/m2 in the spring, which was higher than the forested unrestored site. That site had a maximum of 16.4 m2/m2, which occurred during the fall season.

We are currently preparing her thesis for publication.

March Meanderings

Cross-posted at Highly Allochthonous

It all began at the end of February, when I travelled to La Crosse, Wisconsin to the Upper Midwest Stream Restoration Symposium, which was a really stimulating and vital mix of academics, consultants, and government folks all interested in improving the state of the science and practice of stream restoration. I gave a talk on Evaluating the success of urban stream restoration in an ecosystem services context, which was my first time talking about some hot-off-the-presses UNCC graduate student research, and I learned a lot from the other speakers and poster presenters. While the conference was incredibly stimulating, travel delays due to bad weather on both ends of my trip made for a somewhat grumpy Anne (nobody really wants to spend their birthday stuck in a blizzard in O’Hare), so I’ll be thinking carefully about how to plan my travel to the Upper Midwest during future winters. Nonetheless, the view from the conference venue was phenomenal.

icy river and snowy land

View of the Mississippi River from the Upper Midwest Stream Restoration Symposium in La Crosse, WI. Not shown: bald eagles that frequent the open water patches of the river.

March proper saw me give variations of the restoration talk two other times. On the 15th, I gave it as the seminar for Kent State’s Biological Sciences department, and on the 26th, I gave it at the North Dakota State University Department of Geosciences (more about that trip below). In between, I gave a seminar on the co-evolution of hydrology and topography to the Geology Department at Denison University in Granville, Ohio. Students in that department had just returned from a trip to Hawaii, and a very memorable dialogue occured in the midst of me talking about the High Cascades:

“You’ve seen a young lava flow. What would happen if you poured a bottle of water on it?” “It would steam!” “Not that young!”

Closer to home I also hosted a couple of prospective graduate students, helped interview candidates for a faculty position in our department, and went with a colleague to visit an acid mine drainage site about an hour to the south of Kent. In one fairly small watershed, we were able to tour a number of different remediated and unremediated sites, and it certainly lent a whole different perspective to the ideas of stream restoration and constructed wetlands to look at a landscape irrevocably scarred by mining activities.

Orange water flowing from a tube down a hill and into a stream.

Unremediated acid mine drainage flow directly into Huff Run. The orange is iron precipitate.

Wetland plants and a concrete inlet weir.

Constructed wetland as the second stage of acid mine drainage remediation in the Huff Run watershed.

At the end of the month, we finally got our turn for spring break. I ended up with a somewhat epic combination of mounds of work and a big trip to take, possibly the worst combination of the untenured and tenured professor spring break stereotypes (see this PhD comics strip). The first half of the week, I spent in Fargo, North Dakota, home to the famously flood-prone Red River of the North. (I’ve blogged before about why the river so often produces expansive floods.) It was truly fascinating to put my feet on the ground in a place that I’ve read about and watched from afar for years. And my visit was made all the more interesting by my host and guide, Dr. Stephanie Day, a geomorphologist newly at NDSU and who may well unravel some of the Red’s geomorphological peculiarities.

Scientist in foreground, river in midground, background = flat, snowcovered ground.

Stephanie Day, Assistant Professor of Geosciences at North Dakota State University beside the Red River in Moorhead Minnesota. The flat surface in the background is the approximate elevation of the land for miles around.

Looking towards downtown Fargo, ND from the river side of the levee.

Looking towards downtown Fargo, ND from the river side of the levee.

snow and ice covered river, not in much of a valley.

River’s edge view looking towards downtown Fargo. Snow well over knee deep here on 25 March, by my measurements. As all that snow starts to melt, the water will rise.

There’s a pretty good chance we’ll see a major flood on the Red River later this spring, as the >24″ of snow melts out of the watershed, runs off over frozen ground, and enters the northward flowing river. The Fargo Flood page is the place to go to follow the action, and you can count on updates (and more pictures) here as events unfold.

The latter half of my spring break saw me diagonal across the state of Minnesota to my beloved Driftless Area, back across the Mississippi River, and into the state of Wisconsin. I saw my family, finished paper revisions, and wrote part of a grant proposal. Then I flew home, with nary a weather delay in sight.

If March was a tight, recursive meander of talks and trips to the Upper Midwest, then April promises to be a bit anastomosing with lots of different threads woven together to make another month of scientific delight.

Anne’s November Navigations

Cross-posted at Highly Allochthonous

I’m not joining the exodus of geoscientists to AGU this week; I’m still recovering from November.

I’m not sure whether I spent more time in Ohio or outside of it last month. The month started with the rain and runoff from our brush with Superstorm Sandy, but by November 2nd I had a car packed full of conference and research gear and was heading south to North Carolina. The drive south was a great chance to watch all sorts of geology go by at interstate speeds. I started out in the glaciated Appalachian Plateau, drove south of the glacial limit, crossed the Ohio River, and was soon in the heart of the Appalachians and West Virginia‘s coal mining country. On Interstate 77, the border between West Virginia and Virginia seems to mark the dramatic transition the Valley and Ridge Province, then it is up on to the Blue Ridge and finally down the Blue Ridge Escarpment and into the Piedmont and North Carolina, finally arriving in Charlotte after eight hours of driving. Climatically, I left the cold and damp, drove through the snow left behind by Sandy, and ended up in the warm, sunny, and very dry south.

The Geological Society of America meeting was a busy time. I convened two sessions, helped lead a field trip and had more meetings for committees and with colleagues than I care to remember. But it was a great time to hear about exactly the sorts of science that I find most interesting and to get out in the field with 50 friends and colleagues to talk about new ideas in geomorphology.

  • Geomorphology of the Anthropocene: The Surficial Legacy of Past and Present Human Activities. We had an amazing slate of speakers that packed the room, fantastic poster presenters that drew a crowd, and we were able to announce that we will be editing a special issue of the new journal Anthropocene with papers from the session. Then the journal’s publisher threw us a special reception.
  • Hydrology of Urban Groundwater, Streams, and Watersheds. This session featured another roster of incredible speakers and a kick-ass set of posters featuring many of my students and colleagues from UNC Charlotte.
  • Kirk Bryan Field Trip: Piedmont Potpourris: New Perspectives on An Old Landscape (and Some of its Younger Parts. The annual syn-meeting field trip of the Quaternary Geology and Geomorphology division always features good scenery and intense but friendly discussions. This year we looked at an old mill dam site in an urban stream and channel heads and terrace soils near the Catawba River, and then we climbed a monadnock to talk about Blue Ridge escarpment retreat and the long term evolution of landscapes. Plus, we had a delicious lunch of NC barbecue on our able and charismatic field trip leader’s front lawn.

Missy Eppes atop a red soil pit.

Field trip leader Missy Eppes atop a typically red soil profile, on a terrace above the Catawba River.


50 geomorphologists on the front steps

An enthusiastic and well fed group of geomorphologists and Quaternary geologists on a delightful November day.


Geomorphologists on a rock listening to Ryan McKeon

On top of Crowders Mountain, learning from Ryan McKeon.

After the meeting was over, I stuck around Charlotte for a few days, with plans to do a tracer injection in one of my local field sites. As I’ve already shown you, that didn’t work out so well. So I headed back north.

Back in Ohio, I did some exploring of Cuyahoga Valley National Park, which was timely given that I am just about to submit a proposal to do work in the headwater streams in and around the park. I also spent a wonderful day with someone from the Ohio EPA, looking at dam removal and stream restoration sites in the region.

Stream with sediment and trees

Headwater stream near Brandywine Creek, CVNP, November 2012.

My fun explorations of Ohio streams were tempered with sadness though. Just before Thanksgiving, my sweet, 14-year old canine companion, Cleo passed away. She was my longest running and most faithful field assistant, and I’ll miss her forever.

Dog meets spring

Cleo, in ~2005, at one of my PhD field sites.

But then it was off to Baltimore to visit with Claire Welty and the folks at the Center for Urban Environmental Research and Education, who do some of the coolest urban hydrology work around. They also host the Baltimore Ecosystem Study field site.

Sign on door reads "Baltimore Ecosystem Study"

That was just the warm-up for the real reason for my trip, giving a seminar in the Department of Geography and Environmental Engineering at The Johns Hopkins University. My talk was on “drainage network evolution is driven by coupled changes in landscape properties and hydrologic response,” in which I attempted to integrate the Oregon Cascades, North Carolina Piedmont, and urban landscapes. It was a thrill and an honor to give a Reds Wolman seminar at JHU, which is my undergraduate alma mater, and the experience was made even more memorable by a morning spent exploring stream restoration sites with Profs. Peter Wilcock and Ciaran Harman. We saw some sites that made some sense, and some that were a bit…non-sensical? I will come out and say it, I’m not a fan of what happened to the little granite pegmatite knickpoint where I went as an undergraduate to try to pretend I wasn’t really in the city. But a bit farther upstream, I could see the value in installing some nice structures that stabilized banks and increased accessibility to the stream in a park popular with joggers and dog-walkers.

JHU profs Wilcock and Harman discuss the restoration of Baltimore's Stony Run

JHU profs Wilcock and Harman discuss the restoration of Baltimore’s Stony Run

And that pretty much brought me to the end of November. I’m looking forward to no travel in December, at least until the end of the month. But that doesn’t mean I won’t stay busy.

The wrong conditions for a stream tracer injection

Cross-posted at Highly Allochthonous

Leaving behind Ohio and the high waters from Sandy, I ventured south in early November for the Geological Society of America meeting in my former home of Charlotte, North Carolina. The meeting was busy and wonderful, and far too packed for me to hear as much science or talk to as many people as I would have wished. After the meeting was over, I stuck around Charlotte for a few days in order to do some field work with one of my graduate students. Our plan was to do a tracer injection in one of the headwater streams that form her field area. Such tracer injections are a bit finicky to schedule…if it’s raining or has recently rained, you can’t do them because the stream discharge won’t be steady over the several hours of the experiment. But Sandy had not dropped any rain on the Charlotte area and the weather was beautiful all during the conference. Nonetheless, my student assured me that there would be plenty of water in the stream, as it had been running well just two weeks prior. Perfect conditions, we thought.

So the afternoon before the experiment, we headed out to the study site to measure discharge and mark the places where we would be collecting samples. My student advised me to wear my hip waders, not knee boots, as she had over topped her boots last time she was in the field.

But…it turns we didn’t need the boots. At all.

Piezometers rising from a dry stream bed.

The wrong conditions for a stream tracer injection, November 2012, Charlotte, NC.

Clearly, we could not add our tracer to the streamflow the next day. We were missing one crucial ingredient: streamflow.

One upside to the situation is that it was a very easy call to make. No hemming and hawing and making some sort of judgement about whether things were “good enough” to go for it. We simply couldn’t do the experiment.

It was also stunningly good conditions for walking the channel and looking at the location and conditions of the stream restoration structures and wood jams. And we spent the next day with our heads together working on much more solid plans for the eventual experiment. So, not a total loss.

But now we need to wait, for the right hydrological conditions, suitable ecology, and a time that works in our schedules. Field work is incredibly important for learning about the way that real, complex hydrologic systems work. And it can be incredibly fun. But it can also be filled with frustration…and waiting. In this case, for the “right conditions for a stream tracer injection.”

Abstract: Evaluating the success of urban stream restoration in an ecosystem services and watershed context

I’ll be at the 2013 Upper Midwest Stream Restoration Symposium in LaCrosse, Wisconsin in February. Even though the conference focuses on the Upper Midwest (of which Ohio is a part), I’m going to be talking about work from the southeastern US. Of course, the conference will be a great chance for me to learn from and make connections with stream restoration practicioners and scientists in the Midwest. I’m really looking forward to it, and hopefully they won’t call me out as a carpetbagger. I actually grew up ~25 miles from the conference location.  Here’s the abstract.

Evaluating the success of urban stream restoration in an ecosystem services and watershed context

Anne Jefferson1, Sandra Clinton2, Mackenzie Osypian3, Sara McMillan3, Alea Tuttle2

1. Department of Geology, Kent State University
2. Department of Geography and Earth Sciences, University of North Carolina at Charlotte
3. Department of Civil Engineering, University of North Carolina at Charlotte

In urban watersheds, the capacity of streams to provide essential ecosystem services is often limited as a result of channel straightening, incision and removal of geomorphic features. Stream restoration seeks to provide stream stability while reestablishing ecosystem services, but restoration alone may not mitigate the effects of watershed land-use change and urbanization. Stream restoration activities frequently impact transient storage and hyporheic exchange, the processes by which water movement is slowed down or temporarily detained at the surface or in the streambed. Transient storage and hyporheic exchange zones are important regulators of nutrient retention and stream temperature, and they harbor diverse biological communities. However, it is unknown how successful stream restoration activities are at creating ecologically effective storage and exchange zones that promote improved water quality and nutrient retention. In a series of studies in Charlotte, North Carolina, we have evaluated restored and unrestored streams to quantify and compare transient storage and nutrient retention. Our goal is to evaluate the relative success of restoration activities for ecosystem services in urban and forested watersheds. We measured increased transient storage and greater variability in upwelling and downwelling vertical hydraulic gradients in restored relative to unrestored reaches. However, restored reaches also had lower hydraulic conductivity of bed sediments, which was likely related to to restoration practices such as streambed compaction and installation of landscaping fabric and cement below structures that may reduce the magnitude of hyporheic exchanges. Restored streams also have higher water temperatures than unrestored streams. The removal of riparian vegetation and soil disturbance and compaction during the restoration process, along with continued input of nutrients from fertilizers in urban watersheds can result in a unique water quality signature in urban restored streams. Denitrification rates were variable between sites, but channel complexity and restoration of urban streams appear to increase denitrification, even though hyporheic exchange was generally low. In unrestored urban streams, allochthonous anthropogenic debris (e.g., shopping carts) may contribute to channel complexity and nutrient retention. While current practices of urban stream restoration may be successful in creating channel stability, coupling watershed-scale management of stormwater and nutrients with restoration techniques designed to enhance ecologically effective storage and exchange may be required for restoration success in a holistic sense.

Dense riparian vegetation, dry stream channel, rocks, log, and a muddy pool

One of our restored stream sites, during the summer drydown (August 2010). Beaverdam Creek watershed, Charlotte, North Carolina. Photo (c) Anne Jefferson.