Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 87-97).

This study represents the first shift in multivoltine life history of Cheumatopsyche species from a wastewater treatment plant (WWTP) in North America. Populations of C. lasia were examined upstream and downstream of the Denton’s Pecan Creek WWTP August 2009 through November 2010. C. lasia is multivoltine in Pecan Creek with three cohorts observed upstream of the WWTP and four possible cohorts downstream. A fourth generation was possible downstream as thermal inputs from WWTP effluent resulted in elevated water temperatures that allowed larval development to progress through the winter producing a cohort ready to emerge in spring. Production of C. lasia was 5 times greater downstream of the WWTP with secondary production estimates of 1.3 g m-2 yr-1 and 4.88- 6.51 g m-2 yr-1, respectively. Differences in abundance were due to increased habitat availability downstream of the WWTP in addition to continuous stream flow from inputs of wastewater effluent. Results also suggest that C. lasia is important for energy transfer in semiarid urban prairie streams and may serve as a potential conduit for the transfer of energy along with emergent contaminants to terrestrial ecosystems. These finding highlight the need for more quantitative accounts of population dynamics (voltinism, development rates, secondary production, and P/B) of aquatic insect species to fully understand the ecology and energy dynamics of urban systems.

The stream restoration industry has been growing since the addition and modification of Section 404 to the Clean Water Act. Many projects follow the guidelines of Natural Channel Design and use in-stream structures to stabilize stream channels. Post-project monitoring rarely exceeds 3-5 years, and the lack of guidance, funding, and pre-restoration data prevents meaningful post-project assessment of the design techniques. The Virginia Tech Stream Research, Education, and Management (StREAM) Lab is a research facility where a stream restoration project was completed along 1.3 km of Stroubles Creek in 2010. The study site provides a unique opportunity to compare the use of three restoration treatments with different intensities of restoration actions. Following exclusion of cattle from all three sites, the first treatment reach was left to naturally revegetate (Treatment 1) and along Treatment 2 the streambanks were re-graded to a 3:1 slope and replanted. An additional inset floodplain was constructed within the active channel of Treatment 3. Pre-restoration data, including topographic surveys and erosion pin measurements, provided a baseline for quantification of morphological response 11 years post-restoration. This project utilized as-built survey data from 2010 and a follow-up survey in 2021. The spatial data were analyzed to quantify important stream metrics: cross-sectional area, width, maximum depth, hydraulic depth, and width-to-depth ratio. Overall, the percent change per year of each metric decreased substantially following the restoration, indicating an increase in stability. While Treatment 3 continues to show minor erosion on average (+3.3% in area, +3.2% in width, and +11.2% in maximum depth), Treatments 1 (excluding cross section 5) and 2 decreased on average in area (-3.4% and -18.6%) and hydraulic depth (-13.3% and -10.8%). Treatment 1 eroded by an average of 11.7% in width compared to a decrease of -13.4% in Treatment 2 and an increase in 3.2% in Treatment 3. Comparisons of each treatment to Virginia Mitigation Banking Standards indicated Treatment 1 met the fewest number of criteria, followed by Treatment 2 and then Treatment 3, indicating that hard structures are not necessary to meet mitigation bank standards, even in urban watersheds. In an urban, incised channel with cattle impacts, re-grading the streambanks, actively planting woody riparian vegetation, and incorporating an inset floodplain will accelerate the establishment of channel stability, as compared to the more passive approach of simply removing cattle access to the channel. / Master of Science / The stream restoration industry has been growing since the addition and modification of Section 404 to the Clean Water Act. Specific design models, such as Natural Channel Design which focuses heavily on preventing the stream from moving using stone and wood structures, guide many projects. Post-project monitoring rarely exceeds 3-5 years, and the lack of guidance, funding, and pre-restoration data prevents meaningful post-project assessment of the design techniques. The Virginia Tech Stream Research, Education, and Management (StREAM) Lab is a research facility in which human interactions in the Stroubles Creek Watershed can be evaluated. A stream restoration project was completed on Stroubles Creek at the StREAM Lab property in 2010. This project provides a unique opportunity to compare three different intensities of restoration actions. Following exclusion of cattle from all three sites, plants were left to naturally regrow in the first treatment reach and Treatment 2 re-shaped the banks to a gentler slope and replanted. Like Treatment 2, an additional inset floodplain was constructed within the active channel of Treatment 3. Pre-restoration data, including topographic surveys and bank erosion measurements provided a baseline for quantification of physical response 11 years post-restoration. This project utilized survey data from immediately post-restoration in 2010, and a follow-up survey in 2021. The surveys were analyzed using AutoCAD Civil3D and cross-sectional area, width, maximum depth, hydraulic depth (area/top width), and width-to-depth ratio were calculated. Overall, the percent change per year of each metric decreased substantially following the restoration, indicating an increase in stability. While Treatment 3 continues to show minor erosion (+3.3% in area, +3.2% in width, and +11.2% in maximum depth), Treatments 1 (excluding cross section 5) and 2 decreased on average in area (-3.4% and -18.6%) and hydraulic depth (-13.3% and -10.8%). Treatment 1 eroded by an average of 11.7% in width compared to a decrease of -13.4% in Treatment 2 and an increase in 3.2% in Treatment 3. Comparisons of each treatment to Virginia Mitigation Banking Standards indicated Treatment 3 met the highest number of criteria, followed by Treatment 2 and then Treatment 1, indicating that hard structures are not necessary to meet mitigation bank standards, even in urban watersheds. In an urban, incised channel with cattle impacts, regrading the streambanks, actively planting woody riparian vegetation, and incorporating an inset floodplain will accelerate the establishment of channel stability, as compared to the more passive approach of simply removing cattle access to the channel.

Rivers and streams are sensitive to alterations in their watersheds and one of the greatest disturbances is from urban development. An urban stream channel in the Atlanta metropolitan area in the Georgia Piedmont was studied to establish the nature of adjustment the channel form was experiencing. This study compared a degraded channel with a channel influenced by stabilization efforts in the same stream reach, in order to investigate the behavior of channel adjustments towards a greater stability. Measurements of the short-term changes in channel cross-sectional area and bed-material volume, following a series of threshold flow events, were taken in the reach and the variation in bed sediment texture was also investigated. Results showed that channel banks were stable compared to more mobile beds and that urban effects continued to dictate sedimentation. Rehabilitation measures were aggrading channels in their reaches and were likely perpetuating the instability of upstream channels.

To assess how urbanization impacts stream nutrient uptake, a series of instantaneous (i.e. slug) nutrient additions were conducted in 3 urban and 3 non-urban streams during open and closed canopy conditions. Single additions of N, P, and combined additions of N and P were performed at each site. These data were used to test the hypothesis that high N:P concentrations in urban streams would result in P-limited conditions, and to assess differences in nutrient uptake kinetics (i.e., the relationship between uptake and concentration) between urban and non-urban streams. The results show that there were no consistent differences in N vs. P limitation among urban and non-urban streams suggesting that ambient N:P ratios are not useful predictors of nutrient limitation at the ecosystem scale. Areal uptake rates of N in urban streams were greater than non-urban streams coinciding with elevated N concentrations. Conversely, areal uptake rates of P were similar between urban and non-urban streams because these systems have similar ambient concentrations of P. Urban and non-urban streams demonstrated similar uptake velocity and areal uptake rate responses to increasing nutrient concentrations. However, unique to this study, urban streams had greater uptake velocities at ambient nutrient concentrations. These findings suggest that urban streams could have a greater capacity for nutrient uptake over a broad range of nutrient concentrations, but prior work indicates that this capacity may be constrained by the duration of the nutrient addition.

<p>Currently, cities comprise 52% of the Earth's land surface, with this number expected to continue to grow, as most of the predicted 2.3 billion increase in population over the next 40 years is expected to occur in urban areas (United Nations Population Division 2012). Urban areas necessarily concentrate food, energy, and construction materials, and as a result tend to be hotter and more polluted than the surrounding landscape. All urban ecosystems are thus quite altered from their pre-urban state, but urban streams are particularly impacted. As low lying points on the landscape, streams are subject to the degradation caused by urban stormwaters, which are transmitted rapidly from the surfaces of pavements, roofs, and lawns through stormwater infrastructure to streams.</p><p> The systematic changes seen in many urban streams have been described as the "Urban Stream Syndrome" (USS) and serve as an organizing conceptual framework for urban stream research (Walsh et al. 2005b). A primary symptom of USS is increased flashiness in hydrographs, as stormwater in urban areas is routed efficiently into streams (Booth and Jackson 1997, Konrad and Booth 2005). With this stormwater runoff comes intense scour leading to deeply incised channels, large amounts of contaminants and nutrients, and, as will be discussed in this thesis, heat surges (Booth 1990, Tsihrintzis and Hamid 1997, Walsh et al. 2005a, Nelson and Palmer 2007, Bernhardt et al. 2008). At baseflow, urban streams are contaminated by sanitary sewage leakages, are unable to exchange water with their floodplains due to incision and with groundwater due to lower water tables, and are warmer due to canopy loss and urban heat island effects (Paul and Meyer 2001, Pickett et al. 2001, Groffman et al. 2002, 2003). These baseflow and stormflow changes lead to the loss of sensitive taxa and increase in tolerant biota, as well as changes in ecosystem function, including carbon and nitrogen processing (Paul and Meyer 2001, Meyer et al. 2005, Imberger et al. 2008, Cuffney et al. 2010). </p><p> The urban heat island effect can increase air temperatures up to 10°C above those in surrounding, non-urban areas, while impervious surfaces can reach temperatures up to 60°C (Asaeda et al. 1996, Pickett et al. 2001, Kalnay and Cai 2003, Diefenderfer 2006). These changes are particularly troublesome, as research has shown that temperature is a controlling factor in aquatic systems for both stream biota and ecosystem processes (Allen 1995, Kingsolver and Huey 2008). Thermal changes control and can alter basic morphological features of biota, such as size and growth rates (Gibbons 1970, Kingsolver and Huey 2008). USS synthesis reports have called for further research into the processes by which urban areas influence the temperature of streams and the resulting effects on the ecosystems, but until recently have largely been ignored (Paul and Meyer 2001, Wenger et al. 2009). This dissertation explores the timing, magnitude, and pattern of thermal pollution for streams within urban heat islands, with the goal of understanding what aspects of watershed development most strongly influence the thermal regimes of streams. In order to explore thermal pollution in urban streams, I asked three overarching questions:</p><p> 1) How much hotter are highly urban streams than streams in less developed watersheds?</p><p> 2) How far do urban heat pulses propagate downstream of urban inputs?</p><p> 3) How can development configuration mitigate or exacerbate development amount in mediating urban thermal pulses?</p><p> In Chapter 2, I explore the differences in baseflow and stormflow temperatures in 60 watersheds across the North Carolina Piedmont that ranged across a gradient of urbanization. I asked:</p><p> 1) How do maximum temperatures at baseflow and maximum temperature surges at stormflow differ across watersheds with varying development intensity? </p><p> 2) What reach- and watershed-scale variables are most correlated with these 2 aspects of stream thermal regimes? </p><p> 3) Do stream management approaches (riparian buffers, channel restoration) address the links between these variables and stream temperature?</p><p> I found that the 5 most urban streams were on average 0.6°C hotter at baseflow than the 4 most forested streams. During a single storm event, urban streams showed an increase over five minutes of up to 4°C, while forested streams showed little or no thermal increase. Reach-scale characteristics, specifically canopy closure and width, primarily controlled baseflow temperatures. These local factors were not important drivers of stormflow temperature changes, which were best explained by watershed-scale development and road density. Management that focuses on baseflow temperatures, such as riparian buffers and reach-scale restoration, ignores the intense urban impacts that occur regularly during storm events.</p><p> Next, in Chapter 3, I explore longitudinal temperature patterns in a single stream, Mud Creek, in Durham, North Carolina. Mud Creek's headwaters are suburban, and the stream travels through a number of housing developments before entering a 100-year-old forest. I placed 62 temperature loggers over a 1.5 km reach of this stream. To explore the mechanisms by which stormflow heat pulses dissipate along this stream reach, I asked:</p><p> 1) What is the range of heat pulse magnitudes that occur over a year?</p><p> 2) What is the maximum distance that a heat pulse travels downstream of urban inputs?</p><p> 3) How do the magnitude and distance vary with storm characteristics, including antecedent air temperature and amount and intensity of precipitation?</p><p> I found that heat pulses with amplitude of greater than 1°C traveled more than 1 km downstream of urban inputs in 11 storm events over one year. This long dissipation distance, even in a best-case management scenario of mature and protected forest, implies that urban impacts across a developing landscape travel far downstream of the impacts themselves and into protected areas. Heat pulses greater than 1°C occurred in storms with greater intensity of and total precipitation and greater time of elevated storm flow. Air temperature, flow intensity, maximum flow, and total precipitation controlled the magnitude of the heat pulse, while the distance of dissipation was controlled by the magnitude of the heat pulses and total precipitation. The importance of air temperature, flow, and precipitation metrics imply that both magnitude and distance of dissipation of heat pulses are likely to increase with climate change, as air temperatures increase and sudden, intense storms become more frequent. This translates to even greater ecological impacts in urban landscapes like Durham municipality, where the 98.9% of streams less than 1 km downstream of a stormwater outfall will become even more likely to be impacted by urban stormwaters.</p><p> In Chapter 4, I examine which aspects about development best explain thermal differences observed at baseflow and stormflow. To do this, I selected 15 similarly sized watersheds in the North Carolina Piedmont region within 45 to 55% development that varied in other development characteristics, specifically density of stormwater infrastructure and aggregation of development patches. I asked two questions:</p><p> 1) How does the configuration and connectivity of development within a watershed influence baseflow and stormflow temperatures in receiving streams? </p><p> 2) How do baseflow and stormflow temperatures vary with development characteristics?</p><p> I found that aspects of development varied greatly within this urban intensity subset, with ranges for some metrics nearly equal to the variation observed across all watersheds in the landscape. Longer pipe lengths, shading from incised channels, and shaded impervious surfaces resulted in cooler baseflow temperatures. As in Mud Creek, stormflow metrics were influenced through two physical pathways: air temperature and either flow intensity, to explain overall thermal change, or antecedent flow, to explain intensity of thermal change. Greater sub-surface connectivity of development to the stream network increased thermal responsiveness to storms through faster delivery and greater amount of heated runoff. Greater proportions of forest in a watershed decreased the amount and temperature of runoff delivered to the stream, while development within the riparian zone throughout a watershed led to warm baseflow temperatures and lack of response to stormflow heat surges. By decreasing the connectivity of development to the stream network, thermal regimes of streams can be less impacted even in relatively urban watersheds.</p><p> Thermal pollution in urban streams is a problem that will only be exacerbated by predicted climate change and urban expansion. These findings imply that thermal pollution is a problem throughout urban landscapes, even far downstream of urban inputs and within protected areas, and must be managed as an important component of the USS. Future research should focus on the transferability of these findings to regions outside of the southeastern United States and to the movement of other urban pollutants, and on exploring the potential to manage these systems by decreasing sub-surface connectivity.</p> / Dissertation

The Wissahickon Creek is an urban stream that runs through Montgomery and Philadelphia Counties and discharges to the Schuylkill River in Philadelphia. A majority of stream segments in the Wissahickon watershed are considered impaired by the USEPA due to sediment and nutrients. Total Maximum Daily Loads (TMDLs) were implemented in 2003 for nutrients (NO3-, PO43-, NO2-, and CBOD5) and siltation. A new TMDL for total phosphorus (TP) was proposed in 2015, despite minimal data on the effectiveness of the 2003 TMDLs. This new proposal was met with concern, suggesting more data must be collected to better understand impairment in the Wissahickon Creek. The purpose of this research was to study turbidity and nutrient responses to storm events, as storm events are known to contribute significant loads of both sediment and nutrients. Twelve sites were chosen for high frequency turbidity and water level monitoring along the Wissahickon Creek and one of its main tributaries, Sandy Run. These sites were selected around three of the major wastewater treatment plants (WWTPs) to determine the relative roles of WWTPs and overland flow as sources of turbidity and nutrients during storm events. The upstream site and first downstream site at each WWTP were monitored for nutrients during storms using high frequency loggers and ISCO automatic samplers. Stream assessments were done at each site to characterize in-stream physical parameters, bank vegetation, and algae cover. High frequency turbidity data suggests that the turbidity is locally sourced, as turbidity peaks at the same time as water level, or within an hour or two, at all sites regardless of storm size. Comparisons of the turbidity response with in-stream parameters and land cover helped determine that the main factor driving the turbidity response is discharge, although bank topping and impervious cover, particularly roads, may increase turbidity responses at some sites. Similarities in nutrient, turbidity, and conductivity responses upstream and downstream of the WWTPs strongly suggest that overland flow, not WWTP effluent, is the major source of nutrients and sediment during storm events. Finally, a strong relationship between total phosphorus and high turbidity suggests that only during high discharge events is there a significant increase in TP in the Wissahickon Creek. Results from this research identify the source of turbidity and nutrients to the Wissahickon Creek during storms as primarily coming from overland flow, that the primary factor controlling the turbidity response is discharge, with some secondary influence from over-banking and the contribution of roads to land use, and a close link between TP concentrations and sediment during storms in the stream. / Geology

As the Americans have become more aware of the impact to the environment from the human induced disturbances which includes physical, chemical and biological disturbances to the degradation of streams and rivers, many studies and experiments have been done in an attempt to restore streams and rivers to more natural conditions. At the same time, success in public education and community involvement has encouraged grass-root movements that engage people in stream restoration efforts. Stroubles Creek is a freshwater stream located in Blacksburg, Virginia. The creek has experienced considerable disturbance due to land use changes over the past 100 years. The Stroubles Creek Water Initiative (SCWI), originated by the Virginia Water Resources Research Center at Virginia Tech, has been monitoring the creek for a number of years. This paper develops a planning framework for restoring and/or rehabilitating Stroubles Creek within the Town of Blacksburg. The results of stream monitoring and other research by SCWI are used to inform the recommended planning process, while a literature review and discussion of “urban stream restoration case studies” are used to guide future decision-making related to Stroubles Creek restoration/rehabilitation. / Master of Urban and Regional Planning

No description available.

Urbanization affects in-stream biogeochemical processes that control nutrient export. Attempts to restore urban streams will not be successful unless the biological and physical controls on water quality are thoroughly understood. The objective of this study was to identify the relative influences of tributary dilution, groundwater discharge, and biological processing on nitrate concentrations in an urban stream during high and low flow periods. A wastewater treatment plant (WTP) on Pennypack Creek, an urban stream near Philadelphia, PA, increases nitrate concentrations to a mean of 8.5 mg-l-1 (as N). Concentrations decrease to 5.5 mg-l-1 about 7.5 km downstream. Reaches along this distance were sampled for nitrate concentration and delta-15N at fine spatial intervals to determine the reasons for this decrease. To quantify the effects of dilution, samples were collected from tributaries, groundwater springs, and upstream and downstream of tributaries or groundwater discharge zones identified through terrain analysis and continuous temperature modeling. These methods were also used to identify and sample reaches along which hyporheic flow occurred, where nitrate biological processing is often concentrated. In addition, loggers were installed at closely spaced sites to monitor daily fluctuations in nitrate, dissolved oxygen, and related parameters, which provided further indications of biological processing. Longitudinal sampling revealed decreases in nitrate concentration of 2 and 6.5 mg-l-1 during high and low flow, respectively. During high flow, delta-15N varied from 9.5 to 10.5 per mille downstream of the WTP, while delta-15N varied from 10.14 to 11.06 per mille throughout this reach during low flow. Mixing analysis indicated that groundwater discharge and biological processing both control nitrate concentration during both flow periods. Larger declines in nitrate concentration were observed during low flow than during high flow, and delta-15N fell between biological and groundwater signatures, indicating that both processes were enhanced. Continuous nitrate concentrations displayed distinct diurnal cycles often out-of-phase with dissolved oxygen cycles, indicating autotrophic processing. However, shifts occurred in nitrate cycle timing at a weekly scale wherein daily maximum concentrations were observed as many as 6 hours closer to noon than previously. These shifts were comparable to shifts observed across seasons in other studies, and by the end of the summer, nitrate and dissolved oxygen cycles were in-phase. Furthermore, shifts in nitrate cycles could not be linked to shifts in daily fluctuations of WTP discharge. Longitudinal sampling and continuous monitoring suggest that biological processing is an important control on nitrate concentrations in urban systems, though documenting its signature may be complicated by groundwater discharge and anthropogenic inputs. / Geology