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A High-Resolution Record of Climatic Change in Elk Lake, Minnesota for the Last 1500 Years
A High-Resolution Record of Climatic Change in Elk Lake, Minnesota for the Last 1500 Years
Summary, Earlier investigations of varved sediments from Elk Lake, Minnesota (Fig. 1) based on integrated 50-year samples at 100-200-year intervals illustrated the sensitivity of Elk Lake to climatic change (Bradbury and Dean, 1993). Varve thickness measurements demonstrated the rapid (interannual) nature of climatic variation during parts of the Holocene (Dean and others, 1984; Bradbury and Dean, 1993). Studies of ostracodes (Forester and others, 1987), chironomids (Stark, 1976),and geochemical and mineral properties (Dean, 1993) showed that rapid (decadal to centennial), high amplitude changes in sediment components occured during the time interval of 10,000+ to 4,000 years ago. In contrast to these early and middle Holocene changes in sediment characteristics, the Elk Lake record for the past 4,000 years is more stable, but nevertheless shows lower amplitude variations in many sediment parameters over the last few millennia that testify to significant climatic changes at scales of human importance. In this report we present the initial results of analyses of contiguous samples, each a composite of about five years, to document a high-resolution paleolimnological history of the past 1500 years in Elk Lake. These results chronicle past climatic changes in the north-central US throughout the period of time that encompasses the Little Ice Age, the Medieval Warm Period, distinctive episodes of reduced solar activity (the Maunder and Sporer Minima), and the impact of European settlement and exploitation of the region after AD 1890. The cyclicity of these changes suggests forcing mechanisms related to solar activity and its influence on the strength and direction of near surface wind fields at mid-latitudes in the Northern Hemisphere.Figure 1, Full text
A Holocene Record of Endogenic Iron and Manganese Precipitation, Isotopic Composition of Endogenic Carbonate, and Vegetation History in a Lake-Fen Complex in Northwestern Minnesota
A Holocene Record of Endogenic Iron and Manganese Precipitation, Isotopic Composition of Endogenic Carbonate, and Vegetation History in a Lake-Fen Complex in Northwestern Minnesota
Abstract, Little Shingobee Lake and Fen are part of an extensive network of lakes and wetlands in the Shingobee River headwaters area of northwestern Minnesota. Prior to about 9800 radiocarbon years, most of the lakes in the Shingobee watershed area were interconnected to form glacial Lake Willobee. From 9800 to 7700 radiocarbon years, the level of Lake Willobee fell as a result of breaching of a dam, leaving small separated basins containing the existing lakes and wetlands. The dominant components in the sediments in a 9-meter core from Little Shingobee Lake (LSL–B), and lacustrine sediments under 3.3 meters of peat in a 17-meter core from Little Shingobee Fen (LSF–10) are detrital clastic material, endogenic CaCO3, and organic matter. The detrital fraction in the Holocene section in core LSL–B varies considerably from 7 weight percent to 82 weight percent and closely parallels the concentration of detrital quartz measured by X-ray diffraction. The CaCO3 concentration, which also varies considerably from 10 weight percent to 70 weight percent, is generally antithetic to the detrital concentration owing to the dilution of detrital material by CaCO3, particularly during the early to middle Holocene (about 9000–6500 calendar years). The organic-matter content varies from 5 weight percent to 25 weight percent and, together with CaCO3, serves to dilute the allogenic detrital fraction. In both cores almost all of the iron (Fe) and manganese (Mn) is in endogenic minerals, presumed to be oxyhydroxide minerals, that are important components throughout the core; little Fe and Mn are contributed by detrital aluminosilicate minerals. The endogenic Fe mineral, calculated as Fe(OH)3, forms a larger percentage of the sediment than endogenic organic material throughout most of the Holocene section in the LSL–B core and in the lacustrine sediments below the peat in the LSF–10 core. Biogenic silica as opal (biopal; diatom debris) was not measured, but the average calculated biopal is 5 percent in the LSL–B core and 15.5 percent in the LSF–10 core. Values of δ18O in mollusk (Pisidium) and ostracode shells increase by only about 20 per mil from the bottom to the top of the LSL–B core (about 12600–2200 calendar years). The remarkably constant oxygen-isotope composition throughout the Holocene suggests that environmental conditions affecting values of δ18O (temperature, salinity, composition of the water, composition of precipitation) did not change greatly. Values of δ13C in carbonate shells generally decreased by about 2 per mil from 9000 calendar years to 6000 calendar years, but they did not increase in organic carbon. This mid-Holocene increase in δ13C in shells but not in organic carbon is likely due to an increase in residence time. A late Pleistocene forest dominated by spruce was replaced in the early Holocene by a pine forest. The pine forest migrated east during the middle Holocene and was replaced by an open sagebrush–oak savanna. The western migration of forests into northwestern Minnesota is marked first by a hardwood forest and finally a pine forest., Full text
A New Flashiness index: Characteristics and Applications to Midwestern Rivers and Streams
A New Flashiness index: Characteristics and Applications to Midwestern Rivers and Streams
The term flashiness reflects the frequency and rapidity of short term changes in streamflow, especially during runoff events. Flashiness is an important component of a stream's hydrologic regime. A variety of land use and land management changes may lead to increased or decreased flashiness, often to the detriment of aquatic life. This paper presents a newly developed flashiness index, which is based on mean daily flows. The index is calculated by dividing the pathlength of flow oscillations for a time interval (i.e., the sum of the absolute values of day-to-day changes in mean daily flow) by total discharge during that time interval. This index has low interannual variability, relative to most flow regime indicators, and thus greater power to detect trends. Index values were calculated for 515 Midwestern streams for the 27-year period from 1975 through 2001. Statistically significant increases were present in 22 percent of the streams, primarily in the eastern portion of the study area, while decreases were present in 9 percent, primarily in the western portion. Index values tend to decrease with increasing watershed area and with increasing unit area ground water inputs. Area compensated index values often shift at ecoregion boundaries. Potential index applications include evaluation of programs to restore more natural flow regimes.
A New Planning and Design Paradigm to Achieve Sustainable Resource Recovery from Wastewater
A New Planning and Design Paradigm to Achieve Sustainable Resource Recovery from Wastewater
To employ technologies that sustainably harvest resources from wastewater (for example struvite granules shown here), new perceptions and infrastructure planning and design processes are required.
A PALEOLIMNOLOGICAL STUDY OF DEER YARD AND POPLAR LAKES IN COOK COUNTY, MINNESOTA
A PALEOLIMNOLOGICAL STUDY OF DEER YARD AND POPLAR LAKES IN COOK COUNTY, MINNESOTA
Yes, Summary, Lakes are a prominent feature and a valued resource within the landscape of the glaciated regions of the Upper Midwest. Land and resource use in the watersheds over the past several hundred years, including logging, agriculture, and urban development, have raised concerns over the current state of lakes in this region as well as the best management strategy for the future. Knowledge of the state of a particular lake prior to European settlement, as well as an understanding of the timing and magnitude of historical ecological changes, are critical components of an effective management plan. A basic understanding of natural fluctuations within the system is important for any lake management plan. Reliable long-term data sets, on the order of 30 - 50 years, are generally not available for most regions of the country. Through the use of paleolimnological techniques (reconstructing the history of a lake based on the sediments deposited in its basin) and quantitative environmental reconstruction, we can estimate past conditions, natural variability, timing of changes, and determine rates of change and recovery. This information allows managers and researchers to put present environmental stresses into perspective with the natural variability of the ecosystem. It can also be used to identify response to, and recovery from, short-term disturbances. In this project, paleolimnological techniques were used to reconstruct the trophic and sedimentation history of Deer Yard Lake and Poplar Lake, both located in Cook County in Minnesota’s Arrowhead Region., Full text
A PRACTICAL GUIDE TO ENVIRONMENTAL FLOWS FOR POLICY AND PLANNING
A PRACTICAL GUIDE TO ENVIRONMENTAL FLOWS FOR POLICY AND PLANNING
Yes, Summary, Freshwater scientists around the world acknowledge a crisis in biodiversity loss and diminished ecosystem function in streams, rivers, wetlands and lakes. One main culprit in this decline is human-caused change in the historical magnitude, frequency and timing of river flows that have supported key ecological processes and native species in diverse aquatic systems. The Ecological Limits of Hydrologic Alteration (ELOHA) framework arose as a response to the recognition that the rate of global hydrologic change was outpacing science’s ability to develop environmental flow guidelines one site at a time. A new scientific framework was needed, one to guide the development of environmental flow guidelines at a regional scale. Regional environmental flow management is extremely challenging. Not only are data needs great for underlying hydroecological models, but translation of science into policy and management necessarily occurs in a complex societal context constrained by governance structures, regulatory authorities and competing political interests. A comprehensive and scientifically sound framework was required, yet it had to be flexible enough to accommodate the inevitable “experiments” that will result from its application to real-world settings. This guidebook presents nine case studies in regional environmental flow management in the United States. The successes described in these case studies clearly illustrate that innovative thinking and creative experimentation within the structured ELOHA framework have significantly advanced the development of flow standards at regional scale. The accomplishments are the fruit of the dedicated efforts of innumerable agency, academic and non-government scientists, engineers, water managers, and policy makers, all of whom were willing to think outside the box and take up the challenge of pushing the frontiers of sustainable environmental management of streams and rivers. Their stories are impressive and inspiring! A key contribution of this guidebook is that it distills an excellent synthesis across the case studies and offers valuable insight into transferable lessons learned from individual studies. Importantly, numerous tips and extended discourse are offered on how to adapt the flexible ELOHA framework to streamline and strengthen the scientific process. While a more robust social framework may still be needed to effectively translate science into policy and regulations, the information presented in this guidebook serves as an indispensible resource for all those engaged in protection and management of freshwater ecosystems. The authors of the guidebook are to be commended for their outstanding product, and more generally for their dedication to the cause of science-based freshwater conservation., Full text
A Paleolimnological Study of Net Lake and Lac La Belle, Carlton and Pine Counties, Minnesota
A Paleolimnological Study of Net Lake and Lac La Belle, Carlton and Pine Counties, Minnesota
Yes, Summary, Lac La Belle and Net Lake are located in Carlton and Pine counties. Both lakes are shallow systems with Net Lake reaching approximately 15 feet deep and Lac La Belle at least 16 ft. Net Lake is surrounded by extensive state land holdings and has somedevelopment along its north shore. The lake has been dammed at the outlet for at least50-60 years and is part of the Net River drainage system. Lac La Belle is a shallow, morewetland-like system, with a small area of development on one shoreline. The lake has along history as a stop with a guesthouse along the route from St. Paul to Duluth that wasserved by both rail and stagecoach. Concern for the lakes centers on their currentcondition especially for total phosphorus (TP) levels, because neither lake meets currentstate standards (30 ppb TP) for shallow lakes in the Northern Lakes and Forest (NLF)ecoregion. Net Lake routinely exceeds 40 ppb TP (long-term average TP 40 ppb, chlorophyll a 9 ppb, MPCA 2016a), although there have been no reported algal blooms. Lac La Belle has TP values in excess of 60 ppb and higher long-term average chlorophyll a (43 ppb, MPCA 2016b), and similar to Net Lake, has not had any reports of algalblooms. These impairments have led to questions whether the productivity of the lakeshave changed over time, what the natural or historical condition of the lakes were, whatthe current trajectory of each lake is, and how to best set management goals. Knowledgeof the natural state of a lake and an understanding of the timing and magnitude ofhistorical ecological changes become critical components for any management and remediation plan., Full text
A Quantitative Dye Trace in the Bat River System
A Quantitative Dye Trace in the Bat River System
While in resent years a significant amount of work has been done to delineate the karst spring sheds of southeastern Minnesota. There has been little work done to document the characteristics of the spring sheds such as the resonance time of water with in the system. Bat River Cave and spring were the focal point for this trace, the spring being the sampling location, Four dyes were released, one in a drilled access shaft and three others into near by sinkholes. All four dyes were detected in Bat River Spring within twenty-four hours of there releases. The velocity of the system was found to be 651 ft/hr relative to cave passage and 258 ft/hr compared to the surface distance. This goes to highlight the Galena group's vulnerabilities and the difficulty of contamination containment.
A Regression Model to Estimate Regional Ground Water Recharge
A Regression Model to Estimate Regional Ground Water Recharge
A regional regression model was developed to estimate the spatial distribution of ground water recharge in subhumid regions. The regional regression recharge (RRR) model was based on a regression of basin-wide estimates of recharge from surface water drainage basins, precipitation, growing degree days (GDD), and average basin specific yield (SY). Decadal average recharge, precipitation, and GDD were used in the RRR model. The RRR estimates were derived from analysis of stream base flow using a computer program that was based on the Rorabaugh method. As expected, there was a strong correlation between recharge and precipitation. The model was applied to statewide data in Minnesota. Where precipitation was least in the western and northwestern parts of the state (50 to 65 cm/year), recharge computed by the RRR model also was lowest (0 to 5 cm/year). A strong correlation also exists between recharge and SY. SY was least in areas where glacial lake clay occurs, primarily in the northwest part of the state; recharge estimates in these areas were in the 0- to 5-cm/year range. In sand-plain areas where SY is greatest, recharge estimates were in the 15- to 29-cm/year range on the basis of the RRR model. Recharge estimates that were based on the RRR model compared favorably with estimates made on the basis of other methods. The RRR model can be applied in other subhumid regions where region wide data sets of precipitation, streamflow, GDD, and soils data are available.
A Roving Creel Survey of Selected Southeast Minnesota Trout Streams - 2005
A Roving Creel Survey of Selected Southeast Minnesota Trout Streams - 2005
Thirty-three trout streams were surveyed from April 1 to September 30, 2005 throughout southeast Minnesota in a roving creel survey. Anglers were interviewed, counted, and given a post-card to return indicating total hours fished. Anglers consisted of mostly males (90.2%) using a variety of bait (37.0%), fly (35.3%), lure (20.7%), and mixed method (7.0%) gear types. Mean angler trip length was calculated as 3.77 hours with a catch rate of 1.10 trout/hour. An estimated 214,307 trout were caught in 52,687 angler trips totaling 190,859 angler-hours. Angler harvest rates were 17.3% for brown trout and 34.4% for rainbow trout. This creel will help natural resource managers meet their long-term goal to conserve, enhance, and restore self-sustaining trout populations and their habitats for anglers and the people of Minnesota., Yes, Abstract, Full text
A Scientifically Defensible Process for the Exchange of Pollutant Credits under Minnesota’s Proposed Water Quality Trading Rules
A Scientifically Defensible Process for the Exchange of Pollutant Credits under Minnesota’s Proposed Water Quality Trading Rules
Summary, The Minnesota Pollution Control Agency (MPCA) is drafting statewide water quality trading (WQT) rules. WQT is a flexible tool offering a mechanism to achieve additional economic and environment benefits when used in conjunction with traditional command and control approaches. A permitted wastewater treatment plant facing high costs to accommodate new growth or meet more stringent discharge requirements can “trade” for discharge reduction credits generated by another source having lower costs (e.g., an agricultural producer implementing conservation practices). A portion of the reductions traded can be retired to address uncertainty or to create a net reduction of pollutants (nitrogen, phosphorus, sediments) discharged to the receiving water. MPCA has already issued point‐point and point‐nonpoint trading permits. These permits provide the required authority to implement WQT under NPDES program provisions in advance of the current rule development process. The MPCA has recognized that creating trading frameworks within each NPDES permit allows each framework to be renegotiated. This also results in trading implementation differences from site to site and high costs for administration. Permit renegotiation, as has been experienced in the public notice process, expends valuable time and resources limiting the attractiveness of WQT. To simplify and potentially streamline the WQT permit process, MPCA intends the rules to be used to both define a credible WQT program and remove the complications of permit renegotiation. With specific regards to defining credible program options, MPCA hired Kieser & Associates, LLC to develop key elements of a scientifically defensible process for calculating pollutant reduction credits. This report provides a technical foundation for these related elements of Minnesota’s WQT rule development and related Statement of Need and Reasonableness (SONAR). The Kieser & Associates scope of work set forth to achieve these goals included:  Develop an example stepwise calculation process for approvable non‐point source phosphorus credits in Minnesota.  Demonstrate a method of determining appropriate trade ratios (including uncertainty factors) for phosphorus. A series of statistical analyses will be conducted to examine implications of various ratios. Results will reveal the best method to minimize redundant margins of safety.  Create a logical decision tree transferring the stepwise crediting process for phosphorus to other pollutants. To address these tasks, the report describes efforts associated with:  Benchmarking nationally accepted credit estimation methods  Selection of credit estimation methods to use as examples for Minnesota WQT applications  A defensible eight step process based on sound watershed science to develop MPCA’s proposed “uncertainty factor”  Statistical evaluations of trading program options and credit calculation methods to consider for future WQT program rule applications  A narrative outline and flow diagram providing guidance to WQT program managers for using the eight step process for phosphorus, nitrogen and sediment crediting, Full text

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