Browsing by Subject "stream restoration"

Now showing 1 - 4 of 4
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    Exploring The Impact Of Stream Restoration On Ecosystem Function Through Changes In Nutrient Spiraling
    (2023) Baldus, David
    Millions of dollars have been spent on stream restoration and habitat improvement projects in the Lake Superior watershed. The impact of these projects on ecological function of a stream reach are not well measured or understood. This knowledge gap is echoed within restoration work worldwide. Here we provide a test case of one method for closing this knowledge gap. We use physical habitat characteristics to explain the differences seen in stream function between a restored treatment reach and an unrestored control reach on Sargent Creek (Duluth, MN) using ammonia/ammonium nutrient spiraling dynamics as a process-based measure of stream health and function. Nutrient spiraling dynamics describe the level of benthic microbial activity and hyporheic processes within the stream as well as the ability of the stream to increase uptake rates in response to increased nutrient loading. The stream’s “resilience”, the ability to adapt uptake rates, governs nutrient export within a reach, which impacts catchment-scale water quality concerns such as basin eutrophication. Thus, changes in spiraling dynamics have implications for both stream health in situ as well as for the catchment at large. Pairing process-based measures of stream function with physical habitat characteristics allows us to go beyond identifying differences in stream function and start to explain what is causing those differences. By identifying what specific elements of habitat structure drive the processes tied to stream function we can target restoration efforts to produce higher functional lift in our streams. Nutrient dynamics were characterized at each reach through Tracer Additions for Spiraling Curve Characterization analysis (TASCC). Habitat characterization surveys were conducted at each reach using standardized methods from the National Rivers and Streams Assessment and the Minnesota Stream Quantification Tool to enable comparison with existing datasets. Nutrient dynamics were compared between matched control and treatment reaches to evaluate the effect of full-channel realignment on nutrient dynamics. In this case study we find that the restored reach of Sargent Creek has stronger nutrient uptake and retention, higher biological demand for NH4, and is further from biological saturation than the unrestored reach. We were able to explain these differences in uptake behavior through the interaction of habitat characteristics altered by restoration activities (such as reach slope, pool-riffle spacing, grain size distribution, canopy cover, and riparian vegetation assemblage). This provides a strong argument for the use of paired physical habitat surveys with process-based measures of stream function in restoration monitoring and assessment.
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    Northshore Stream Restoration Assessment Physical Habitat Survey Data
    (2023-08-17) Baldus, David, B; Gran, Karen, B; baldu024@d.umn.edu; Baldus, David, B
    These data are the result of a field season of physical habitat surveys conducted on control and treatment reach pairs at six stream restoration projects. Physical habitat characterization survey procedures were adapted from the NRSA Physical Habitat Characterization Survey and the Minnesota Stream Quantification Tool. They include longitudinal and cross-sectional survey data, grain size distribution data, as well as riparian and in-channel habitat data. The treatment reach of each pair was restored and the control reach was not. The control reach was not treated as a degraded pre-restoration reach nor as the standard to be restored to but rather as a representative reach undisturbed by restoration efforts. These surveys were conducted as part of an effort to assess the effects that restoration practices have on a stream ecosystems.
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    Sargent Creek Nutrient Injection Breakthrough Curve
    (2022-09-15) Baldus, David, B; Gran, Karen, B; baldu024@d.umn.edu; Baldus, David, B
    Breakthrough curve data from nutrient injection tracer tests conducted at Sargent Creek on 2021-09-15 and 2021-09-22. The tests were conducted in two stream reaches, the treatment reach which was restored with a full channel realignment in 2019 and the control reach which was not restored. These tracer tests were conducted as part of an effort to assess the effects that restoration practices have on a stream ecosystems. A solution of nutrients (Potassium Nitrate (KNO3), Ammonium dihydrogen phosphate ((NH4)H2PO4)) and a conservative tracer (Sodium Chloride (NaCl)) dissolved in stream water was injected into the stream at the top of the reach as an instantaneous release. Water samples were collected in the thalweg at downstream end of the reach to describe reach-scale nutrient spiraling. Additionally water samples were collected at two sites located mid-reach at the upstream and downstream end of a representative riffle type habitat unit to describe the nutrient cycling within these individual habitat units. Timing of sampling was determined by a conductivity meter in order to capture rising, peak, and falling concentrations and generate a breakthrough curve (BTC).
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    Using Water Budgets and Isotope Analysis to Explore Water Availability in Low Flow Conditions: Hartley Pond Case Study
    (2024) Olbertz, Madison
    Quantifying seasonal changes to the volume and timing of water flowing through a reservoir provides valuable information for responsible resource management. Hartley Pond is a reservoir in Duluth, Minnesota, that is formed by a dam on Tischer Creek. Solar forcing to the reservoir elevates the summer water temperature to a level that is unhealthy for native Brook Trout. One option to address this impairment involves decoupling the stream from the pond. Tischer Creek would flow alongside the pond and maintain a natural water temperature while Hartley Pond would be fed by groundwater and excess streamflow during storm events. For this to work, water inputs from these sources must be high enough to sustain the pond without stream inputs under low flow conditions. To answer questions about the volume and sources of water discharge into and out of Hartley Pond, I built water budgets during low flow conditions in late summer. Streamflow, groundwater, precipitation, evaporation, runoff, and pond volume data were collected to build monthly water budgets for June, July, and August 2023. Accompanying stable isotope analysis of stream, pond, and groundwater samples refined elements of the water budget. Results from the water budget show that inputs into Hartley Pond are dominated by streamflow. Isotope analysis supports the finding that evaporation outputs are greater than groundwater inputs. Therefore, the plan to disconnect the stream from the pond may not be viable because the hydrologic integrity of the pond cannot be maintained through low flow conditions without streamflow inputs. Information gained from the water budget will help local resource managers create a feasible restoration project for Hartley Pond that meets community and environmental needs.