Jean C. Sifneos

Trends and patterns in section 404 permitting requiring compensatory mitigation in Oregon and Washington, USA

The effects of permitting decisions made under Section 404 of the Clean Water Act for which compensatory mitigation was required were examined. Information was compiled on permits issued in Oregon (January 1977–January 1987) and Washington (1980–1986). Data on the type of project permitted, wetland impacted, and mitigation project were collected and analyzed. The records of the Portland and Seattle District Offices of the US Army Corps of Engineers and of Environmental Protection Agency Region X were the primary sources of information.The 58 permits issued during the years of concern in Oregon document impacts to 82 wetlands and the creation of 80. The total area of wetland impacted was 74 ha while 42 ha were created, resulting in a net loss of 32 ha or 43%. The 35 permits issued in Washington document impacts to 72 wetlands and the creation of 52. The total area of wetland impacted was 61 ha while 45 ha were created, resulting in a net loss of 16 ha or 26%. In both states, the number of permits requiring compensation increased with time. The area of the impacted and created wetlands tended to be ≤0.40 ha. Permitted activity occurred primarily west of the Cascade Mountains and in the vicinity of urban centers. Estuarine and palustrine wetlands were impacted and created most frequently. The wetland types created most often were not always the same as those impacted; therefore, local gains and losses of certain types occurred. In both states the greatest net loss in area was in freshwater marshes.This study illustrates how Section 404 permit data might be used in managing a regional wetland resource. However, because the data readily available were either incomplete or of poor quality, the process of gathering information was very labor intensive. Since similar analyses would be useful to resource managers and scientists from other areas, development of an up-to-date standardized data base is recommended.

Developing nutrient criteria and classification schemes for wadeable streams in the conterminous US

Abstract We analyzed nutrient data from a probability survey of 1392 wadeable streams across the 48 conterminous states of the US and from intensified survey data in 921 streams in the Pacific Northwest (PNW) to examine different methods of setting nutrient criteria and to develop a nutrient stream typology. We calculated potential nutrient criteria for total P (TP) and total N (TN) by 3 methods (ecoregion population 25th percentile of population, least-disturbed reference-site 75th percentile, and disturbance modeling) and compared them with existing draft US Environmental Protection Agency (EPA) criteria within 14 national nutrient ecoregions. All criteria derived from the methods were highly correlated; however, absolute values within ecoregions differed greatly among approaches. Population 25th percentiles of TP were almost always lower from statistically designed survey data than from found data. TN percentiles were more similar than were TP profiles, but they still tended to be lower from survey data than from found data. TP and TN population 25th percentiles were lower (often by a factor of 2–6) than reference-site 75th percentiles in all ecoregions. This result indicates that population 25th percentiles cannot be used as surrogates for reference-site 75th percentiles. Thirty-nine percent of the assessed national stream length exceeded TP criteria and 47% exceeded TN criteria when compared to nutrient criteria based on EPA Wadeable Stream Assessment reference-site 75th percentiles. In the PNW data set, all disturbance regression model estimates of background nutrient concentrations were lower than reference-site 75th percentiles. Regression tree analysis based on PNW reference sites used runoff, elevation, acid neutralizing capacity, forest composition, substrate size, and Omernik level III ecoregion as environmental class predictors to explain 46 to 48% of the total deviance in nutrient concentration. Reference-site nutrient concentrations varied widely among Omernik level III ecoregions in nutrient ecoregion II. Our analysis and the literature strongly suggest that 14 national nutrient ecoregions are too coarse to account for natural variation in stream nutrient concentrations. Setting appropriate national nutrient criteria will require finer-scale typology or classification of sites that better controls for natural variation.

Effects of Section 404 permitting on freshwater wetlands in Louisiana, Alabama, and Mississippi

Information was complied on permits issued under Section 404 of the Clean Water Act for alteration of freshwater wetlands from January 1982-August 1987 in Louisiana, Alabama, and Mississippi. The location, area, wetland type, and other data describing the impacted and compensatory (i.e., created, restored, and preserved) wetlands were compiled and analyzed. Trends in Louisiana, the state with the most permits issued, were emphasized, and a synopsis of the results from Alabama and Mississippi is presented for comparison. The objective of the study was to uncover patterns and trends in Section 404 permitting in the three states to document the effects of the permit decisions. Only the information contained in the permit record was compiled and analyzed. No judgment was made concerning compliance with the terms of the permits or whether the compensatory wetland replaced the ecological functions of the wetland destroyed. Neither could be determined from the permit record. In Louisiana, 226 permits were issued, resulting in a potential loss of over 10,000 hectares of primarily forested wetlands. Compensatory mitigation was required in 93 permits (41%); however, only 8% of the total area impacted by all permits issued was compensated. Over 50% of the wetlands impacted were less than or equal to 4 hectares in size. Permitted activities occurred throughout Louisiana, but the majority were located along the Gulf coast and the Mississippi and Atchafalaya Rivers. Food chain support and wildlife habitat were the most commonly listed impacted functions in the permit record. Specific objectives for the mitigation projects were not documented. Only 10% of the compensatory wetlands were monitored by at least one site visit. The Section 404 permitting program could be evaluated more effectively if record-keeping was standardized. The accuracy and thoroughness of this report was affected by poor record-keeping and inconcise permit language. Requirements for follow-up monitoring and increasing the specificity of the information contained in the permits would provide information on the impacts to wetlands and their functions to be considered in future permit decisions.

Using multiple approaches to develop nutrient criteria for lakes in the conterminous USA

Abstract.  We analyzed nutrient data from the National Lakes Assessment (NLA), a probability survey of 1028 lakes >4 ha in lake area across the conterminous USA to quantify and contrast different methods of setting nutrient criteria. We calculated potential nutrient criteria for total P (TP), total N (TN), and chlorophyll a (Chl a) by 4 methods (25th percentile of population, 75th percentile of least-disturbed reference sites, diatom-based paleolimnological reconstruction, and stressor modeling) and compared them to existing draft US Environmental Protection Agency (EPA) criteria within national nutrient ecoregions. At the national scale, the ecoregional criteria derived from the different approaches were highly correlated. However, absolute values differed widely among approaches within ecoregions. Population 25th percentiles were lower (often by a factor of 2–6) than values obtained with other approaches in almost all ecoregions, results indicating that population 25th percentiles cannot be used as a surrogate for reference-site or paleolimnological approaches. Stressor regression models often did not explain much of the variance in nutrient concentration, especially in the less-disturbed ecoregions. For TP, diatom-inferred paleolimnological criteria were higher than reference-site-based criteria, which were higher than stressor-model criteria. For TN, these 3 approaches were very comparable. For Chl a, the reference-site and stressor-model approaches gave similar criterion values in low-nutrient ecoregions, but the reference-site 75th-percentile approach had much higher criterion values than the stressor-modeling approach in the high-nutrient ecoregions. Use of NLA reference-site 75th percentiles as nutrient criteria showed that 42% of the assessed lakes exceeded TP criteria, 47% exceeded TN criteria, and 32% exceeded Chl a criteria. Survey results also suggest that most lakes are P limited. Ninety-three percent of the lakes in the population had molar TN∶TP ratios > 16, and 52% had TN∶TP > 50.

Calibration of the Delaware Rapid Assessment Protocol to a Comprehensive Measure of Wetland Condition

The importance of monitoring and assessment to the management and protection of wetlands has become widely recognized. Wetland assessments are made at multiple intensity levels based on data quality, the application scale, available resources, and the level of effort involved in data collection. We used multiple regression to calibrate the output of a rapid assessment method to condition scores derived from a comprehensive assessment. Data collected at riverine, depression, and flat wetlands in the Nanticoke and Inland Bays watersheds of Delaware and Maryland were used to calibrate the Delaware Rapid Assessment Protocol to an Index of Wetland Condition (IWC) derived from hydrogeomorphic variables. The resulting calibrated rapid condition score was highly correlated with the intense IWC score in each wetland type (r = .88 for riverine, r = .82 for depressions and flats). The calibration methodology was also robust with respect to different statistical cutoff values and model selection methods. Our approach provides a quantitative alternative to using best professional judgment to determine rapid assessment scoring coefficients. Additionally, when rapid and comprehensive methods are correlated, double sampling, a statistical sampling method, can be used to increase the overall sample size resulting in either increased precision of condition estimates or lower sampling costs.

Regression Tree Cartography

We illustrate several types of cartographic displays that can enhance understanding from hierarchical analysis techniques such as regression trees. When the observations have spatial locations, maps of the predicted values, maps of the residuals, and maps of the predicting relationships of the tree may help to reveal associations between predictors and response. We propose an objective method for constructing maps that may help to show the geographical similarities and differences between observations based on their positions in the prediction tree. This mapping method divides the color spectrum to assign colors to the leaves, using the same hierarchical pattern as the prediction tree does to divide the data. We illustrate regression tree cartography with two examples and suggest how the prediction tree mapping method could be used for classification trees and for dendrograms produced by hierarchical clustering methods.

Farmland Heterogeneity Benefits Birds in American Mid-west Watersheds

Abstract It is now well known that biodiversity in agricultural landscapes can be increased by converting production lands (i.e., farmland) into more natural habitat. However, it remains relatively unknown to what extent biodiversity can also be enhanced by changing the composition and configuration of farmland per se. We examined relationships between farmland structure and avian biodiversity in six watersheds representing a gradient in rowcrop intensity in the American Mid-west. We used canonical correspondence analysis (CCA) to model relationships at the site (0.8 ha), field (21 ha), section (165 ha) and watershed (4000–18,000 ha) extents to explore these questions: (1) At what spatial extent do birds respond most strongly to farmland structure? (2) Which farmland variables are most important? (3) Does avian biodiversity increase with increasing farmland heterogeneity? Most variation in bird assemblages was explained at the field versus the site or section extents. Of the top 20 field-extent variables in CCA, most important were: % woodland, an index of compositional heterogeneity (the modified Simpsons evenness index, MSIEI), % rowcrop, % core pasture (i.e., away from an edge), and edge density. Eighteen species were associated with woodland; their richness increased with woodland from 0% to 10%. Nine species were associated with rowcrop; their richness decreased two-fold with a change in rowcrop from 80% to 3%. Twelve species were associated with farmland heterogeneity; their richness increased four-fold with more field cover heterogeneity (MSIEI) and decreased three-fold with increasing mean field size from 1.2 to 7 ha. Field-extent &agr; and &bgr; species richness were significantly higher than expected in the null model in the two most heterogeneous watersheds and lower in the two most intensely farmed watersheds. Differences among watersheds were significant and evident in the CCA ordination plot. Our results show empirically that policies to influence farmland heterogeneity could provide a conservation benefit to avian biodiversity.