A Preliminary Assessment of Ten Watersheds Intersecting Albemarle County, Virginia

Transcription

1 A Preliminary Assessment of Ten Watersheds Intersecting Albemarle County, Virginia Graduate Comprehensive Exam Land Use and Hydrology/ Water Resources Focus Noah D Antonio January 17, 2008 Revised. January 30,

2 Table of Contents Executive Summary. 1 Section 1. Introduction...1 Section 2. Land Use Interactions with Water Resources 4 Section 3. Data Collection and Methods.5 Section 4. Analysis and Recommendations 8 Section 5. Watersheds Recommended for Conservation a. Rockfish River b. Hardware River 14 5c. James River- Near Hatton Ferry..15 5d. South Anna River. 16 Section 6. Watersheds Recommended for Restoration.17 6a. South River on the Shenandoah..18 6b. South Fork Shenandoah River c. South Fork Rivanna River d. North Fork Rivanna. 22 6e. Rivanna River f. Rapidan River...24 Section 7. Limitations and Suggestions for Further Study...25 Section 8. Discussion. 26 Appendix 1. Watershed Data 28 Appendix Meter Buffer Land Cover Data 29 References..30 2

3 Executive Summary A preliminary assessment of ten watersheds intersecting Albemarle County, Virginia was completed for concerned citizens of the county and surrounding municipalities. Each watershed has been analyzed and recommendations have been made based on several land cover variables that are known to impair the integrity of water quality, quantity and natural resources. This assessment is designed to prioritize watersheds and make suggestions for further investigation based on specific issues of concern. Each watershed has been designated as in need of conservation or restoration efforts. Several conservation and restoration techniques are described briefly. Watersheds in need of restoration should not disregard conservation and watersheds in need of conservation should not disregard restoration. Citizens of Albemarle County should be primarily concerned with the Rivanna, North Rivanna, and South Rivanna River Watersheds. This watershed assessment was not designed as a decision making document, but simply to promote an understanding of the processes at hand and assist as a guide towards successful watershed planning (Kershner 1997). Section 1. Introduction Rapid population growth and urbanization raises concern to citizens about the sustainability of their natural resources and water quality. Watershed restoration and conservation are often the best means of protecting these resources for future generations. A preliminary assessment of ten watersheds in Albemarle County, Virginia was completed in order to make recommendations and prioritize watersheds in need of restoration efforts, conservation actions, or in need of a more complete analysis (Figure 1). Urbanization, riparian buffer destruction, and poor agricultural practices have threatened natural resources and water quality in the region. 3

4 Albemarle County has been a recognized leader in water resource protection in Virginia. The county has been implementing water resource protection for over 25 years and developed proper stormwater management before it was required. Ordinances have been set for groundwater protection, and the county is a leader in implementation of the Chesapeake Bay Preservation Act. Although 95% of the county is considered rural, the annual growth rate is 1.5% and is threatening natural resource lands. Recently, county planners have developed growth management plans for development areas, and set goals to increase protection of rural areas, including permanent conservation easements, and water resources (Strategic Planning 2006). Land cover, impervious surface area, and tree canopy density were analyzed in a Geographic Information System in order to determine recommendations based on a set of criteria. All of the watersheds were determined to be in need of a more detailed analysis however, recommendations on conservation or restoration were completed. Of the ten watersheds analyzed six are in need of restoration and four are in need of strict conservation ordinances. Citizens of Albemarle County should be most concerned with a more detailed study of North Rivanna, South Rivanna, and the Rivanna Basins. 4

5 Figure 1. Albemarle County, Virginia and intersecting watersheds. 5

6 Section 2. Land Use Interaction with Water Resources Understanding the impacts of land use on our resources is vital in successful watershed planning, restoration, and conservation. Suburban style development, urban sprawl, has spread people further away from cities into farmlands, forests, wetlands, and other resource lands (Schueler 1994). During urbanization soils are compacted and natural land cover changes to residential housing, industry, and transportation routes, creating impervious surface area (ISA) (Booth et al. 2002, Schueler 1994). Urbanization changes the hydrology, water quality, riparian buffer, topography, soils, and vegetation of the watershed while increasing the pollutant load (Booth et al. 2002, Schueler 1994). Pollution in urban areas and agricultural lands comes from either point sources such as pipes and culverts, or non-point sources in the form of overland runoff. Non-point source pollution from agricultural and urban runoff is the greatest pollution problem (Schueler 1994). Nitrogen and other nutrients run directly off of farm fields into streams, and pollutants from cars and industry build up on impervious surfaces until flushed by a rainstorm, both causing stream impairment (Schueler 1994). Agricultural impacts on water quality include; stream warming, sedimentation and erosion, and most of all increased nutrient loads (Boesch 2001). Stream warming and bank erosion are most often caused by a lack of a riparian buffer that acts to stabilize streambanks and provide shade. Erosion and high levels of nutrient inputs are often due to poor agricultural practices. Over grazing and land clearing leads to increased sedimentation in streams and large amounts of fertilizer cause flushes of nitrogen and phosphorous (Boesch 2001). Eutrophication is increases in organic matter that results in oxygen depletion, known as apoxia, or hypoxia which is oxygen concentrations too low to support organisms (Boesch 2001). The effects are most detrimental downstream in estuaries such as the Chesapeake Bay. 6

7 Researchers and planners often use impervious surface area as an indicator of water quality and watershed health due to the negative relationship between urban area and aquatic health (Booth et al. 2002, Schueler 1994). In general stream health decline begins between 10 to 15 percent impervious surface area. However it is important to note that this varies depending on the watershed sensitivity, initial stream water quality, and other factors, such as agriculture, which may affect stream health (Schueler 1994, Booth et al 2002). Total impervious area (TIA) refers to all of the land cover that does not allow water to infiltrate, including buildings, roads, sidewalks and other non-infiltrating surfaces (Brabec et al. 2002, Booth et al. 2002, Schueler 1994). In urbanized areas precipitation is often moved rapidly through gutters, drains, and sewer systems directly to stream channels. Impervious surfaces that are directly linked to this system are known as effective impervious areas (EIA). Effective impervious areas are often hard to delineate and more difficult to study. Due to decreased infiltration and increased runoff, groundwater recharge is limited affecting groundwater as resource and in turn lowers stream base flow (Booth 2002). Runoff from a one-acre parking lot can be 16 times greater than that of a one-acre meadow (Schueler 1994). Changes to the natural stream flow regime including increased runoff, peak discharge, velocity, downstream flooding, increased runoff temperature, lack of shading, and stream channel instability impair water quality and overall aquatic stream health (Booth et al 2002). Urban planning should initiate storm water management techniques and riparian restoration in order to dampen the effects of impervious surfaces and increased pollutant loads. Section 3. Data Collection and Methods Ten watersheds were assessed using a GIS in order to identify areas in need of restoration or conservation practices. Datasets used for the analysis include: 2001 National Land Cover 7

8 Data (NLCD) land cover, impervious surface, and tree canopy density; USGS HUC 11 watershed boundaries; and USGS National Hydrography Datasets (NHD). The NLCD land cover, impervious surface, and tree canopy layers are mapped at a 30x30 meter resolution and were used as the mapping unit for this study. The NLCD land cover dataset is divided into 16 different classes including, high, medium, and low intensity residential development. The land cover was reclassified to water, urban, forest, agriculture, and wetlands (Table 1). Brabec and others (2002) describe measuring impervious surface as equating the percentage or urban area with the percentage of imperviousness, therefore the urban land cover percentage will be used as the priority measurement for the analysis (Appendix 1). Using urban land cover also allows for direct comparison to other land covers including forest and agriculture. Table 1. Land cover reclassification Reclassified Land Cover Water Urban Forest Agriculture Wetlands NLCD Land Cover Open water Developed, Open Space Developed, Low Intensity Developed, Medium Intensity Developed, High Intensity 41 - Deciduous Forest 42 - Evergreen Forest 43 - Mixed Forest 81 - Pasture/Hay 82 - Cultivated Crops 90 - Woody Wetlands 95 - Emergent Herbaceous Wetland The NLCD impervious surface data is classified into 101 possible values from 1 to 100 percent for each pixel (U.S.G.S. 2001). The actual percent ISA was calculated for each watershed as well as the mean percent ISA (Appendix 1). Actual percent ISA was calculated for each watershed by first changing each of the 101 values into a percent from 0 to 100. The 8

9 number of pixels for each value was then multiplied by 900m 2, in order to get the area of each percent value. All the area values were totaled and divided by the total watershed area in order to get actual percent ISA. The mean ISA was calculated which simply represents the mean impervious pixel value within the watershed (Appendix 1). Percent developed was calculated for each watershed by reclassifying the NLCD impervious data to include pixels with greater than 10 percent ISA as urban (Appendix 1). The area of the reclassified urban was calculated and divided by the area of the watershed in order to obtain percent developed. Percent developed was calculated to better represent urban areas that include pervious surfaces such as compacted lawns that often act as impervious surfaces (Booth et al 2000). Canopy density ranks each pixel from 0 to 100 percent based on tree density but does not discern tree type. Canopy density is often dependent on agriculture and urban areas and was not used in the final analysis. The final analysis used the reclassified NLCD land cover data at both the watershed and 30 meter stream buffer scales (Appendix 1, Appendix 2). It should also be noted that impervious cover is often underestimated when using remotely sensed data due to terrain variability, high canopy closure, shadowing, and seasonality issues (Cablk 2003). General analysis was completed at the watershed scale for ten basins using the HUC 11 watersheds that intersect Albemarle County. Stream data were used from the United States Geological Survey National Hydrography Dataset (NHD) and a 30 meter buffer was created from the center of the stream channel (Figure 2). Reclassified land use data, impervious surface, and percent developed were masked to each watershed. The total percent of each land cover class was calculated (Appendix 1). Total percent developed, total ISA, and mean ISA were also 9

10 calculated for each watershed (Appendix 1). Land cover percents and percent developed were used for the analysis, while mean ISA and total ISA were disregarded. Mean ISA and total ISA were not used because the percent of urban land cover and developed percent were used which better represented developed areas. The 30 meter stream buffer was then used to analyze the land covers within the buffer (Figure2, Figure 3). The land cover was combined with the buffer and percents of each land cover were calculated (Appendix 2). The land use data was then used to analyze and prioritize the watersheds. Figure meter buffer from center of stream channel. Figure meter buffer with reclassified land uses. Section 4. Analysis and Recommendations Criteria were set for the watershed analysis based on stream health rankings from Goetz and others (2003). Goetz and others (2003) derived stream health rankings from remotely sensed data for small watersheds based on tree cover, impervious surface cover, and tree cover in a 100 foot (~30 meter) riparian buffer (Goetz et al 2003). Stream health was based on physical and biological metrics as well as an index of biotic integrity. A 30 meter buffer was used because it has been found that there is a positive correlation with species and taxa richness of macroinvertebrates and the amount of forest cover within the 30 meters. As well there is a negative correlation between percent urban land cover in the 30 meter buffer and fish species richness 10

11 (Goetz 2006). At 30 meters it is generally accepted that riparian buffers can successfully remove pollutants and nutrients from runoff. Generally, the results suggest no more than 6 percent impervious with at least 65 percent forested buffer for an excellent stream rating, and no more than 10 percent impervious with at least 60 percent forested buffer for a good rating (Goetz et al 2003). More specific results are displayed in Table 2. The effects of impervious surface area on stream health also depend on variables such as slope, soils, and distance to streams that are further discussed in Section 7. The stream health ratings were most correlated to impervious cover and tree cover in riparian areas, which were used in determining the criteria for this study. Stream health was determined for each watershed based on Table 2, percent forested buffer and percent urban. Often stream health fell in between Goetz et al (2003) rankings so the rankings are estimated based off of the percent forested buffer then percent urban land cover. All watersheds would have ranked excellent for stream health based percent tree cover. Using these metrics as an indicator of stream health is a generalized method and stream health varies depending on, the sensitivity of the watershed, soils, topography, geology, distance to urban areas, agricultural practices, types of pollutants and many other variables. Goetz et al. (2003) basis for excellent, good, fair, and poor stream health may or may not fit the circumstances in these watersheds. A better understanding of the watersheds, stream quality, and having a reference stream would allow for better integration of stream health in this study. Table 2. Stream Health Rankings based on Tree Cover and Percent Urban *Recreated from Goetz et al Stream Health Rating Percent Tree Cover in Watershed Percent Buffer Forested Percent Urban* Excellent Good Fair Poor * Percent urban land cover 11

12 A set of criteria modified from Goetz and others (2003) were determined for land use at the watershed scale and impervious surface within a 30 meter buffer from the center of the stream channel. Two metrics, the reclassified NLCD land cover data and percent developed area were used to determine the recommendations. Mean and actual ISA were not used as a determining criterion (Appendix 1). Mean ISA was excluded because it is simply the mean percent imperviousness of all the pixels within the watershed and has limited use in this study. Actual ISA was not used as criteria because urban land cover and percent developed better represent development patters. The two metrics used include developed areas which may have a more profound effect on hydrology and watershed health. The criteria for watersheds in need of conservation efforts are; forest land cover at least 70%, forest buffer at least 63% and 6% or less urban land cover in the watershed. Watersheds recommended for restoration met the following criteria; less than 70% forest land cover, at least 6% urban land cover, 6% urban in the 30 meter buffer and greater than 2.5% percent developed. At times the 30 meter buffer entailed a large percent of water land cover which is further discussed in Section 8 Prioritization of watersheds was based on the urban riparian land cover. Urban riparian land cover was ranked high to low for conservation or restoration and the given highest priority. Land cover in the 30 meter buffer took priority over watershed land cover because of its negative correlation with stream health (Goetz 2006). Final recommendations, priority, and estimated stream health, for each watershed are listed in Table 3 and shown in Figure 4. 12

13 Table 3. Watershed Recommendations and Prioritization Watershed Recommendation Priority* Estimated Stream Health Rating Rockfish R. Conservation 1 fair-good Hardware R. Conservation 2 fair-good James R. Conservation 3 good South Anna R. Conservation 4 excellent South River Shenandoah Restoration 1 poor-fair South Fork Shenandoah R. Restoration 2 poor-fair South Fork Rivanna R. Restoration 3 poor-fair North Fork Rivanna R. Restoration 4 poor-fair Rivanna R. Restoration 5 fair Rapidan R. Restoration 6 fair *Priority watersheds for further assessment. Figure 4. Watersheds and recommendations 13

14 Section 5. Watersheds Recommended for Conservation Conservation efforts are used in order to protect the natural resources from development and further disruption. Conservation often requires the efforts of local planners and land owners in order to resist development, especially in areas pressured by high growth like Albemarle County. Specific goals include protecting sensitive areas (wetlands, forests, erosion prone land, ground water recharge areas) from development through zoning and city growth limits to promote sustainable development. Booth and others (2002) describe conservation as using integrated mitigation techniques. This includes, limiting impervious surface area, forest retention policies, stormwater detention, riparian conservation, the protection of wetlands and development on steep slopes, which are practiced by Albemarle County (Strategic Plan 2006). Limiting impervious surface area does not always limit low-density residential development that in turn often creates more forest clearing and negative effects on water quality; therefore cluster development should considered as an alternative option. Maintaining forest cover is often as critical to water quality as limiting impervious surfaces (Booth et al 2002). Limiting development within riparian areas is essential for stream health because of its filtering abilities and role as habitat. Albemarle County requires stormwater best management practices (BMPs) such as rain gardens, green roofs, underground detention basin and constructed wetlands all promote successful conservation (Strategic Plan 2006). Conservation of agricultural land is also important for economic purposes and preventing outward development. However, preservation of agricultural lands still threatens the integrity of water quality due to nutrient loading, erosion of pasturelands, sedimentation of stream water, and stream warming due to a lack of forested riparian buffers (Fisher 2006). To limit water quality concerns, conservation practices that should be implemented include but are not limited to, 14

15 conservation tillage, conservation buffers, crop nutrient management, grazing control, and erosion and sediment management plans. For conservation it is important to identify watersheds that have low urban area with high water quality, and to protect these areas by developing management goals (Booth 2002). 5a. Rockfish River The Rockfish River watershed is primarily located in Nelson County and the most eastern portion of the basin intersects with Albemarle County. The area of the watershed is Km 2 and the primary land cover is forest (83%) (Figure 5, Appendix 1). The most northeastern portion of the watershed contains a majority of the percent developed (2.3%) area in the basin, which extends south from the city of Waynesboro (Figure 6, Appendix 1). The 30 meter buffer created around stream channels contains forest (69%), agriculture (19%), and urban (10%) land covers (Appendix 2). Rockfish basin meets the criteria; (70%) forest land cover, (63%) forested buffer, and (6%) urban, to be conserved. The stream health ranking for the watershed would be projected as fair to good (Table 3). The Rockfish Basin was recommended (1 st ) for conservation practices because of issues that arise in the most northern portions of the watershed where outward development is occurring, from the city of Waynesboro. Strict development and impervious surface limits will help mitigate impacts from growth. Rockfish watershed also has 646km of stream channel that is crucial to protect through riparian protection and zoning limitations throughout agricultural lands. Preventing forest clearing and establishing a stormwater management plan before further development are important conservation efforts. 15

16 Figure 5. Rockfish Basin Land Cover Figure 6. Rockfish Basin Percent Urban 5b. Hardware River The Hardware River basin is primarily located in Albemarle County and the most southern part of the basin is located in Fluvanna County. The area of the watershed is Km 2, the smallest watershed being analyzed, and the predominant land covers are forest (70%) and agriculture (24%) (Figure 7, Appendix 1). Within the 30 meter buffer of the stream channel, land cover is forest (63%) and agriculture (28%) (Appendix 2). The basin met all of the criteria for conservation practices and the stream health rating for the watershed would be projected as fair to good (Table 3). Generally the impervious surface areas are roadways that tend to lead to suburban growth, especially in agricultural landscapes. Although percent developed was calculated at (2%) (Figure 8, Appendix 1), nearly 6% of the land cover is urban and preventing the expansion of impervious surface area is crucial. Conservation efforts within the watershed should be designed to protect forest and agricultural lands within the landscape as well as placing impervious area limitations. Overall, some restoration efforts should be included within riparian 16

17 buffer zones dominated by agriculture or urban land cover. As well, it is important to set up best management practices such as conservation tilling, planting row crops etc. to prevent nutrient loading from non-point sources in agricultural areas. Figure 7. Hardware River Basin Land Cover Figure 8. Hardware River Basin Percent Urban 5c. James River- Near Hatton Ferry The James River basin intersects the southernmost part of Albemarle County and is also the southernmost basin being examined. The watershed also intersects with Nelson, Buckingham and Fluvanna counties. The area of the watershed is Km 2 and the predominant land covers are forest (74%) and agriculture (19%) (Figure 9, Appendix 1). Within the 30 meter buffer zone the land covers are forest (68%) and agriculture (14%) (Appendix 2). This particular buffer zone did include 14% water. The watershed met the criteria for conservation practices and based on the stream health rankings the watershed would promote good stream health (Table 3). The James River basin was recommended (3 rd ) for conservation practices and particular concerns for this watershed would be agricultural areas with no riparian buffers and little canopy. Most agricultural land surrounds the town center and is adjacent to the James River. To promote 17

18 conservation, riparian buffer restoration should be done where feasible along the main stem of the river. There was a 1.4 percent developed area mostly in a growing town in the northeastern part of the watershed (Figure 10, Appendix 1). By designated growth boundaries and limiting impervious surface areas the watershed should be able to sustain a healthy stream, steady agriculture, and protection of forests and open space. Figure 9. James River Basin Land Cover Figure 10. James River Basin Percent Urban 5d. South Anna River The South Anna River basin is generally located within Louisa County, but intersects Orange and Albemarle Counties. The area of the watershed is Km 2 and the predominant land covers are forest (66%) and agriculture (25%) (Figure 11, Appendix 1). Within the 30 meter riparian buffer land cover is forest (64%), agriculture (18%), and wetlands (12%) (Appendix 2). This would rank the stream health as excellent (Table 3). Percent developed in the watershed is 2% (Figure 12, Appendix 1). The basin was ranked 4 th for conservation. A small city in the northern part of the watershed could expand further into the watershed without implementation of specific 18

19 development ordinances or growth boundaries. The large amount of wetlands would be highly beneficial to the stream water quality and protection is also vital in a conservation plan. Wetlands remove nutrients and pollutants from runoff and ground water before entering streams and rivers. Construction of more wetlands in the agricultural areas would be beneficial in preventing high loads of nitrogen and phosphorous into the streams. Figure 11. South Anna R. Basin Land Cover Figure 12. South Anna R. Basin Percent Urban Section 6. Watersheds Recommended for Restoration Restoration actions occur after damage or major alterations have occurred to an ecosystem and the goal of is often to offset degradation and make improvements where possible. Goals should be based off reference conditions that are measurable and provide a range of watershed conditions. These conditions should be based off of historical trends, data, and observations in order to represent the most natural conditions for the landscape (Kershner 1997). Recommendations for managing resources should then be directed from these goals (Kershner 1997). 19

20 Restoration of riparian stream buffers and the implementation of BMPs into agricultural and urban areas are necessary for successful watershed management. Restoration efforts in agricultural areas involve nutrient management and erosion and sediment control measures. Riparian buffers are important as not only a habitat for wildlife but also for their filtering capabilities and removal of nutrients and pollutants (Goetz et al 2003, Kershner 1997). Riparian restoration can be successful in both urban and agricultural areas. Restoration in urban areas often involves construction of riparian buffers, constructed wetlands, infiltration trenches, and vegetated buffers in order to reduce magnitude and pollutant loads of runoff. 6a. South River on the Shenandoah South River basin is located primarily in Augusta County, bordering Albemarle County. The city of Waynesboro resides in the center of the watershed. The watershed is Km 2 in area and the city of Waynesboro is approximately 40Km 2 in area. The predominant land covers in the watershed are forest (59%), agriculture (26%) and urban (15%) (Figure 13, Appendix 1). Within the 30 meter stream buffer there is forest (61%), agriculture (22%) and urban (13%) (Appendix 2). All of the designated criteria for watershed restoration are met. The watershed would rank fair to poor based on the urban percentage (15%) and low forest percentage within the buffer area (61%) (Table 3). The South River Shenandoah watershed was ranked (1 st ) in need of restoration efforts due to urban cover within the riparian zone (13%). Percent developed was measured at (10%) the highest of all watersheds (Figure 14, Appendix 1). There are 462 km of stream to be assessed and a further GIS analysis would be useful in determining critical areas. The city of Waynesboro should begin to set up its own stormwater management program, if not already designed. There should also be strict city growth limits set. In terms of restoration, the area should concentrate its 20

21 efforts on reducing pollutant loads from non-point source runoff within the city. This would include construction of riparian buffers, wetlands, and stormwater BMPs. Figure 13. South River Basin Land Cover Figure 14. South River Basin Percent Urban 6b. South Fork Shenandoah River The South Fork Shenandoah River Basin is the northernmost watershed being analyzed and is located in Page and Rockingham Counties. The western most portion of the watershed borders the city of Harrisonburg. The area of the watershed is Km 2 and the predominant land covers are forest (65%) and agriculture (26%) (Figure 15, Appendix 1). Urban land cover is (8%) and urban land cover within the 30 meter buffer is (10%) (Appendix 2). Also, within the 30 meter buffer land covers are, forest (56%), agriculture (21%) and water (12%) (Appendix 2). Based on the stream health rating the South Fork Shenandoah River basin would rank poor to fair (Table 3). Percent developed (5%) landscapes are spread throughout the agricultural land cover in the basin (Figure 16). Based on the determining criteria the South Fork Shenandoah River is in the need of restoration efforts as well as conservation actions and has been prioritized (2 nd ). Specifically this 21

22 is due to the high percent of urban land cover within the 30 meter buffer zone (10%). Improved stormwater management is necessary and on site detention should be installed in order to control flow duration not just peak flow (Booth et al. 2002). Riparian buffer and wetlands should also be constructed, especially in areas with high urban land cover in the 30 meter buffer area. There are approximately 500 km of streams within the basin and further determination of stream sections in need of mitigation is important. Figure 15. South Fork Shenandoah Basin Land Figure 16. South Fork Shenandoah Basin Percent Urban 6c. South Fork Rivanna River The South Fork Rivanna River basin is located in Albemarle County just north of the city of Charlottesville. The area of the watershed is Km 2 and the predominant land cover includes forest (67%), agriculture (23%), and urban (10%) (Figure 17, Appendix 1). Within the 30 meter stream buffer the land cover includes forest (58%), agriculture (27%), and urban (9%) 22

23 (Appendix 1). The criteria were met to recommend restoration of the watershed. Based on the corresponding stream health measurements the stream health would rank poor to fair (Table 3). The South Fork Rivanna River Basin was prioritized (3 rd )in need of restoration efforts. Although percent developed is only (5%) it is important to analyze the locations of the urban areas (Figure 18, Appendix 1). A large percent of the urban area occurs in the most eastern part of the watershed, the most downstream, and expands outwards. There are also several major roadways which urban development is moving down. It is important to begin implementation of strict zoning ordinances, especially in terms of transportation routes (Schueler 1994). Restoration is necessary within riparian zones due to percent urban land cover (9%) and less than 60% forested buffer in 465km of streams. Stormwater mitigation BMPs within the urban centers is critical for the areas downstream of Charlottesville. Figure 17. South Fork Rivanna R. Basin Land Cover Figure 18. South Fork Rivanna R. Basin Percent Urban 23

24 6d. North Fork Rivanna The North Fork Rivanna Basin is located Primarily in Greene and Albemarle counties and is in close proximity to the city of Charlottesville. The area of the watershed is Km 2 and the primary land covers are forest (67%), agriculture (23%), and urban (9%) (Figure 19, Appendix 1). Within the 30 meter stream buffer land cover is predominantly agriculture (32 %) and forest (57%) (Appendix 2). There is also (8%) urban land cover within the buffer, which meet the criteria to be restored, and percent developed is (5%) (Figure 20, Appendix 1). Based on the forested buffer (57%) and urban land cover (9%), the watershed ranked poor to fair stream health (Table 3). The North Fork Rivanna River was ranked (4 th ) in need of restoration. Being an agricultural landscape within the buffer zone (35%) the watershed would benefit from restoration and mitigation efforts. Riparian restoration efforts, wetland construction, and nutrient management BMPs within agricultural areas would help in reducing nutrient loads into the streams. Stormwater management BMPs should also begin to be put in place along with zoning ordinances to prevent forest clearing for development (Booth 2002). There are 300 km of streams to be assessed and a more detailed GIS analysis could help further determine the sections in need of restoration. It can also be noted that a majority of the forested land cover occurs in the most northern part of the watershed 24

25 Figure 19. North Fork Rivanna Basin Land Cover Figure 20. North Fork Rivanna Basin Percent Urban 6e. Rivanna River The Rivanna River basin is located primarily in Albemarle and Fluvanna Counties and the city of Charlottesville is located within the watershed. The area of the watershed is Km 2, and the primary land cover includes forest (68%), agriculture (18%), and urban (12%) (Figure 21, Appendix 1). Within the 30 meter buffer land cover includes forest (66%), agriculture (17%), and urban (7%) (Appendix 2). The stream health within the basin is rated fair (Table 3). The watershed was ranked (5 th ) for restoration however the City of Charlottesville and the surrounding areas could cause significant water quality impairments. Specific city growth limits should be put in place to prevent more urban spread. Approximately (8%) of the watershed is developed that suggests restoration efforts should be put in place within the watershed and riparian areas (Figure 22, Appendix 1). Within the watershed stormwater management efforts should begin which include constructed wetlands, underground detention 25

26 basins, and rain gardens. Along stream channels, riparian buffers should be constructed to reduce flooding and pollutant loads. Figure 21. Rivanna R. Basin Land Cover Figure 22. Rivanna R. Basin Percent Urban 6f. Rapidan River The Rapidan River Basin intersects with Madison, Greene, Orange and Albemarle Counties. The watershed has an area of Km 2 and the predominant land covers are forest (57%) and agriculture (36%) (Figure 23, Appendix 1). In both the watershed and riparian buffer land cover is urban (6%), but percent developed is only (3%) (Figure 24). Within the remaining 30 meter buffer the land cover is forest (41%) and agriculture (49%) (Appendix 2). The stream health ranking would be poor to good (Table 3). The Rapidan River Basin was prioritized as last (6 th ) for restoration efforts and conservation practices are as important in this watershed as restoration (Table 2). Restoration efforts in the Rapidan River Basin would expand through much of the watershed, due to the large 26

27 amounts of agriculture (49%) and urban area (6%) within the buffer. This means there is little vegetated buffer and no tree shading for the stream. This would indicate stream warming, and heavy nutrient loads entering the stream from agriculture. Using farming and stormwater BMPs is crucial in this landscape. By only allowing cluster development, protecting agriculture, and mitigating some agricultural runoff this watershed should allow for future generations to have the same resources available. Figure 23. Rapidan River Basin Land Cover Figure 24. Rapidan River Basin Percent Urban Section 7. Limitations and Suggestions for Further Study The watershed scale analyzed in this preliminary study was useful in determining watersheds whose water resources and ecological integrity may be impaired. However, a further analysis at the sub-watershed scale would provide a more useful insight on which areas are of greatest concern. Mapping of impervious surface area at the sub-watershed scale, with a more detailed land use classification and applying the tree cover data would help in determining more suitable study sites. Analysis of canopy within the 30 meter zone would better determine 27

28 riparian zones in need of restoration. A more integrated study of agricultural lands would also be beneficial due to their water quality impacts. Detailed analysis should be completed based on priority watersheds listed in Table 2 of this report. Several issues arose which should be further analyzed for all watersheds. The most pertinent issue is ground water and surface water quality. Water quality data might include chemical, physical and biological properties such as ph, temperature, stream bank erosion and sedimentation, fish species richness, and aquatic macroinvertebrate data. Essentially, with these data streams and watersheds with poor water quality can be further investigated. Reference stream should be set up in order to determine an appropriate classification for comparison of stream health and land use within a watershed. This information can then be used in setting up future management goals. At the watershed scale of analysis, landscape metrics such as fragmentation, distance to streams, slopes, and patchiness can be included. Using a Digital Elevation Model to analyze slope and runoff would be one example of such a variable which could help delineate areas in need of stormwater management or riparian buffers. These metrics are also useful for analyzing effective impervious area (Booth 2002). Several watersheds encountered a 30 meter buffer that was not sufficient for classifying the riparian buffer. Because the buffer was based around the NHD stream layer, 30 meters to either side of the stream center, water was often classified. In this case a 60 meter or greater buffer should be calculated in order to observe the riparian buffer. Section 8. Discussion Population growth is inevitable but watershed and county conservation planning can play a vital role in protecting the integrity of water quality and natural resources. Understanding land 28

29 cover interactions with water resources is as essential as farmland and forest conservation. This preliminary assessment is an example of how one county can assess the current status of resources. Although this assessment uses data from seven years ago, and does not give specific locations or stream health ratings based on water quality, it is a necessary first step in watershed planning. Specific restoration or conservation practices are recommended for each watershed as well as priority for action. An important next step is to do an analysis at the sub-watershed scale. This includes site visits and water quality samples to determine more specific areas. Funding should not be prioritized based on restoration or conservation needs but in terms of cost benefit and what will promote the best watershed health into the future. Reference stream and watersheds should be established in order to set appropriate goals for each watershed (Kershner 1997). As well, each watershed and sub-watershed should have its own conservation and restoration plan since no watersheds are identical. Agriculture lands should be protected using sound BMPs (in order to promote stream health), forests preserved, and proper planning with implementations such as cluster development encouraged. Restoration should be completed where necessary and conservation efforts should be put in all county plans. With these suggestions Albemarle County should be able to further investigate the necessary watersheds and continue with a more detailed study of priority watersheds. 29

30 Appendix 1. Watershed Data Watershed Recommendation Priority Estimated Stream Health Rating* Area (Km 2 ) Land Cover 5 Total Stream "Percent Length (Km) Actual %ISA 1 Mean ISA 2 developed" 3 Urban 4 Forest Agriculture Wetlands Rockfish R. Conservation 1 fair-good % 6.25% 83.17% 10.13% 0.00% Hardware R. Conservation 2 fair-good % 5.63% 70.00% 23.82% 0.05% James R. Conservation 3 good % 4.23% 73.52% 19.14% 0.41% South Anna R. Conservation 4 excellent % 4.36% 66.25% 25.27% 2.10% South River Shenandoah Restoration 1 poor-fair % 14.79% 59.15% 25.67% 0.00% South Fork Shenandoah R. Restoration 2 poor-fair % 8.34% 64.55% 26.02% 0.00% South Fork Rivanna R. Restoration 3 poor-fair % 9.96% 66.63% 22.55% 0.02% North Fork Rivanna R. Restoration 4 poor-fair % 9.14% 66.80% 23.41% 0.12% Rivanna R. Restoration 5 fair % 12.12% 68.38% 17.60% 0.76% Rapidan R. Restoration 6 fair % 6.25% 57.00% 35.99% 0.21% *Based on urban land cover and forested riparian land cover 1Actual ISA derived from NLCD dataset 2 Mean ISA of NLCD Impervious dataset 3NLCD Impervious layer was reclassified to Urban = 10% or greater Impervious surface 4Urban development derived from NLCD Land Cover 5 Land Cover totals do not equal 100 percent due to removal of selected land covers 28

31 Appendix Meter Buffer Land Cover Data Watershed Recommendation Priority Estimated Stream Health Rating* Land Cover 2 Total Stream Length (Km) Water Urban 1 Forest Agriculture Wetlands Rockfish R. Conservation 1 fair-good % 9.81% 69.30% 18.63% 0.02% Hardware R. Conservation 2 fair-good % 6.43% 62.97% 28.38% 0.29% James R. Conservation 3 good % 2.54% 67.88% 13.48% 2.11% South Anna R. Conservation 4 excellent % 2.09% 63.88% 18.36% 11.76% South River Shenandoah Restoration 1 poor-fair % 13.39% 61.30% 22.23% 0.00% South Fork Shenandoah R. Restoration 2 poor-fair % 10.44% 56.05% 21.48% 0.00% South Fork Rivanna R. Restoration 3 poor-fair % 9.46% 57.73% 27.22% 0.15% North Fork Rivanna R. Restoration 4 poor-fair % 7.54% 57.30% 31.60% 1.05% Rivanna R. Restoration 5 fair % 6.61% 65.88% 17.30% 4.32% Rapidan R. Restoration 6 fair % 5.99% 40.92% 48.97% 1.20% 1 Urban development derived from NLCD Land Cover 2 Land Cover totals do not equal 100 percent due to removal of selected land covers *Based on urban land cover and forested riparian land cover 29

32 References: Boesch F. Donald, Brinsfield B. Russell, Magnien E. Robert Chesapeake Bay Eutrophication: Scientific Understanding, Ecosystem Restoration, and Challenges for Agriculture. Journal of Environmental Quality 30: Booth B. Derek, Hartley David, Jackson Rhett Forest Cover, Impervious-surface Area, and The Mitigation of Stormwater Impacts. Journal of the American Water Resources Association (JAWRA) Brabec Elizabeth, Schulte Stacey, Richards L. Paul Impervious Surfaces and Water Quality, A Review of Current Literature and Its Implications for Watershed Planning. The Journal of Planning Literature 16(4): Cablk M. E., Minore T. B., Detecting and Discriminating Impervious Cover with High Resolution IKONOS Data using Principal Component Analysis and Morphological Operators. INT. J. Remote Sensing 24(23): Goetz J. Scott Remote Sensing of Riparian Buffers: Pas Progress and Future Prospects. Journal of the American Water Resources Association pg Goetz J. Scott, Wright K. Robb, Smith J. Andrew, Zinecker Elizabeth, Schaub Erika IKONOS Imagery for Resource Management: Tree cover, Impervious surface, and Riparian Buffer Analyses in the Mid-Atlantic Region. Remote Sensing of the Environment. 88: Fisher Thomas, Benitez A. Jorge, Lee Kuang-Yao, Sutton J Adrienne. History of land cover change and biogeochemical impacts in the Choptank River basin in the mid-atlantic region of the US. International Journal of Remote Sensing. 27[17] Kershner L. Jeffery Setting Riparian/Aquatic Restoration Objectives within a Watershed Context. Restoration Ecology. 5[4] Schueler R. Thomas The Importance of Imperviousness. The Practice of Watershed Protection Techniques. 1(3): Strategic Plan Albemarle County, Virginia. U.S. Geological Survey. HUC 11 watershed boundaries. and U.S. Geological Survey National Land Cover Data U.S. Geological Survey. National Hydrography Dataset. 30