Loch Alpine Lakes Rehabilitation Feasibility Study
Prepared for: Loch Alpine Board and Lakes Committee Prepared by JJR Incorporated 110 Miller Ann Arbor, Michigan 48104 |
The Loch Alpine residential community is located approximately five miles northwest of the City of Ann Arbor, Michigan. The northern portion of the 450-acre community is located in Webster Township and the southern portion is in Scio Township, which are both townships in Washtenaw County (Figure 1).
JJR Incorporated was retained in the spring of 1999 to conduct a Lakes Rehabilitation Feasibility Study. Included in this study summary report is: 1) a description of the existing natural features and built conditions within the watershed of the lakes; 2) identification of goals and objectives developed by community members for lake rehabilitation; 3) a discussion of alternative methods considered; 4) a description of why lakes rehabilitation is needed; and, 5) recommendations for the lakes, recreational enhancements and storm water management improvement. A glossary of terms used in this document is presented in Appendix A.
An assessment of the existing conditions surrounding and within the Loch Alpine community was conducted by JJR during spring and summer 1999. The assessment included a review of existing published information and several field visits (Appendix B). The focus of field reviews was to determine:
Information collected and reviewed is summarized as follows under the headings of “Watershed Characteristics,” “Stream and Drainage Characteristics,” “Lake and Shoreline Characteristics,” and “Land Use Surrounding the Lakes.”
The lakes within Loch Alpine are known as the Upper and Lower lakes (the U.S. Geological Survey named them Bridgeway Lake and Green Oak Lake). The lakes receive their surface water contribution from Boyden Creek and associated tributaries, a few storm drains, and runoff from adjacent properties. These surface waters ultimately drain into the Huron River. The Boyden Creek watershed covers approximately eight square miles (Figure 2).
Land use within the Boyden Creek watershed has been dramatically altered from its pre-settlement condition. Prior to settlement of the area (during the early 1800’s) the watershed contained mostly oak-hickory forest with pockets of mixed oak savanna (MDNR, 1998). Over the next hundred years, the watershed was mostly cleared for agricultural use, however, the stream corridors and wetlands remained wooded, and a few upland woodlots were retained.
Figure 1. Project Site Location Map
Figure 2. Boyden Creek Watershed
A few homes that border the county roads within the watershed (such as Joy Road, Webster Church Road, Jennings Road, and Stein Road) appear to have been built in the late 1800’s, although, most appear to have been built within the last fifty years.
The community of Loch Alpine consists of approximately 500 single-family homes. Most of the home lots are approximately one-third of an acre in size and appear to have been developed between 1955 and 1975 (specifically the southern three-quarters of the community). The northern quarter of Loch Alpine was developed within the last five years. Similarly, other residential neighborhoods surrounding Loch Alpine such as North Delhi Hills and Glen Devon have developed in recent years (see Figure 2). A new residential development, The Preserve, is currently under construction in the former Barrett gravel pit area west of Loch Alpine.
Homes within the southern three-quarters of Loch Alpine contain mature trees and established landscaping. The mature vegetation is believed to be an aid in reducing the rate of storm water runoff from the properties. The northern quarter of the subdivision contains new homes with few mature trees. Storm water runoff from lawns, building roofs and pavement within Loch Alpine drains either to a series of vegetated swales adjacent to roads that eventually lead to Boyden Creek or the lakes, or sheet flows toward the golf course or the two lakes. Storm water runoff from North Delhi Hills and Glen Devon drains to sediment/detention basins and low-lying wooded areas prior to entering drainage swales leading to Boyden Creek and the lakes.
Land upstream of Loch Alpine is mostly cultivated (soybean, corn and wheat). Most of the farm fields were observed to be using no-till practices, which was confirmed by the U.S.D.A. Farm Service Agency. No-till farming benefits surface water quality by reducing sediment runoff. Drainage channels near farm fields are vegetated with a combination of native trees, shrubs, and grasses along the channel banks.
Washtenaw County maintains most of the through roads within the watershed, including:
Huron River Drive, North Delhi Road, Joy Road, Webster Church Road, Jennings Road, Northfield Church Road, Maple Road, and Stein Road (Posegay, 1999). Many of the county roads are unpaved, which may be contributing to the sediments within the watershed drainage channels. Zeeb Road is also a county through road, which is located just west of the watershed boundary (see Figure 2).
Truck use of Huron River Drive is prohibited without a permit from the Washtenaw County Road Commission. Huron River Drive may be used as a “Temporary Haul Road” with a permit to transport material between properties located between intersecting county through roads.
Loch Alpine, Glen Devon, and North Delhi Hills roads are private roads and maintained by the respective neighborhood associations. Almost all of the roads within these neighborhoods are paved with a bituminous surface and are paralleled by drainage swales containing turf grass, cobble stone and boulders, or wetland vegetation. Drainage swales are a type of best management practice (BMP) for storm water management. Curbs occur in some areas to direct storm water to specific drainage points along the roads.
JJR representatives participated in a field review meeting on the Ann Arbor Country Club golf course with the golf course superintendent (Mr. James Racine) in late May 1999. The purpose of the site visit was threefold and included: 1) gaining information regarding golf course maintenance practices; 2) reviewing streambank stability within the golf course; and 3) discussing opportunities for implementation of storm water management activities.
The golf course is located primarily within the floodplain of Boyden Creek; therefore, maintenance activities occurring within and adjacent to the floodplain potentially affect the creek and surface water quality. Overall, golf course maintenance activities observed and discussed during the meeting are consistent with storm water best management practices (BMPs) recommended in the Cost Estimating Guidelines – Best Management Practices and Engineered Controls (Wayne County Rouge Program Office, 1997) and the Guidebook of Best Management Practices for Michigan Watersheds (MDNR, 1992). Approximately half of the golf course soils are classified as either Adrian muck or Houghton muck, indicating that they are high in organic content. Mr. Racine stated that the golf course applies approximately one-third of the fertilizers that are typically used by golf courses because the organic soils naturally have high nutrient levels. Similarly, the golf course uses approximately one-third of the irrigation typically used by golf courses. Golf course irrigation pond water is supplied by a groundwater well and is also pumped from the creek. Mow clippings from turf maintenance are left on rough areas and fairways to naturally decompose. Clippings are collected from greens, and occasionally tees, and spread on rough areas at least 50 feet away from the streambank. Brush from tree and shrub trimmings is burned.
Mr. Racine noted that the Huron River Watershed Council Adopt-a-Stream program has sampled macroinvertebrates (water quality indicators) upstream and downstream of the golf course. Sampling data has been provided to JJR from the Watershed Council and reviewed as part of the Lakes Rehabilitation Feasibility Study (see Appendix C).
The Loch Alpine community is situated in an area dominated by glacial moraine, outwash deposits and till. The highest elevation within the watershed (per U.S. Geological Survey quadrangle maps) is approximately 1,000 feet. Within the Loch Alpine community, the highest elevation is approximately 940 feet and the lowest elevation is 833 feet. The topography of Loch Alpine generally slopes toward the Boyden Creek valley and the two lakes within the central portion of the community (Figure 3). Slopes vary from nearly level within the valley to very steep within residential areas of the community; most of the steep slopes average between 10 and 20 percent grade.
Several soil types have been identified within the Loch Alpine community (USDA-SCS, 1977) and are generally associated with the various landforms (Figure 4). Most of the central valley area, which is in golf course use, is characterized by Gilford sandy loam; a soil common to low-lying areas and drainageways of outwash plains. This poorly drained soil typically consists of sandy loam to a depth of approximately three feet, which is underlain by gravelly sand. At the northern boundary of the Loch Alpine community, two tributaries to Boyden Creek flow through an area containing Adrian muck. As the name indicates, this soil type contains muck to approximately two feet deep, underlain by gravelly sand. Gilford and Adrian soils are hydric soils (i.e., capable of supporting wetland vegetation) with shallow depths to seasonal high water tables (0 to 1 feet below the ground surface). A third hydric soil, Houghton muck, is located within a fairly large area on the golf course property, south of Whitman Circle Drive.
Surrounding the lakes a variety of soils types are identified, including:
A small area of Wasepi soil is located in the vicinity of the creek channel downstream from Lower Lake. This soil is located on broad low-lying areas of outwash plains, but it is not a hydric soil. Boyer loamy sand is located along the southern boundary of Lower Lake and along the western boundary of Upper
Figure 3: Loch Alpine and Ann Arbor Country Club Existing Conditions/Analysis
Lake, including the Loch Alpine Park area (see Figure 4). Boyer soil is well-drained, formed in loamy and sandy deposits of outwash plains and moraines, underlain by gravelly coarse sand. The seasonal water table is generally less than five feet from the surface. Within the park, groundwater seeps were observed during field reconnaissance. Fox soil extends around the northwestern portion of Lower Lake. This well-drained soil type is located in upland areas associated with outwash plains and moraines. Miami loam is a well-drained soil formed in loamy textured glacial till. On the Loch Alpine site, Miami loam covers broad areas and is located along drainageways that lead to Boyden Creek and the lakes. Runoff from Miami loam on steep soils is very rapid and soil erosion can be severe.
Boyden Creek is a tributary of the Huron River (see Figure 2). The slope of the stream channel is fairly steep with an average fall of 17 feet per mile. Surface water elevation and stream discharge rises and falls rapidly in response to rainfall; therefore, the stream is considered to be “flashy”. The main branch of Boyden Creek (Stream 1) enters the site along the northeast boundary of the Loch Alpine site and flows southwest towards the lakes. On route to the lakes, two tributaries (Streams 2 and 3) intersect Stream 1. Stream 2 enters the site through two culverts under Joy Road along the north boundary of the site and flows south, intersecting with Stream 1 approximately 300 feet south of Loch Alpine Drive East (within the northern portion of the community). Stream 3 enters the site on the northwest boundary of the site and flows east intersecting Stream 1 approximately 200 feet south of the confluence of Streams 1 and 2. Stream 4 is small tributary that flows southeast within the boundary of the Loch Alpine Park. This tributary appears to convey water from groundwater seeps. Stream 4 discharges into Upper Lake near the former swimming beach area. Stream 5 is a small, intermittent tributary that conveys surface water from hillsides and woodlands that extend beyond the southeast site boundary. Near Loch Alpine Drive East, Stream 5 is diffuse and fairly undefined, however, downstream a channel exists with bank erosion. Sediments from the bank erosion are carried in the stream’s flow to Lower Lake.
During dry weather, streams in the Loch Alpine community and within the watershed are clear and appear to transport very little sediment. Stream 1 within the Ann Arbor Country Club property maintains a constant flow and exhibits a bottom composed of cobble, gravel and silt. Flow is confined to the lower one-quarter of the channel cross-section. Areas of erosion of the stream bank are visible during dry weather. Eroded sections of the stream are primarily located in areas where the streambank lacks woody vegetation including areas within the golf course and Rock Park (see Figure 3). During dry weather, the appearance of Stream 2 is similar to Stream 1, however, the bottom substrates are covered and embedded in silt.
During wet weather, Streams 1 and 2 are very turbid (cloudy) and appear to transport significant quantities of fine sediment. Stream 2 appears to receive sediment from agricultural land north of Joy Road and from the road itself. These sediments are released in a plume as Stream 1 enters into Upper Lake, eventually giving the lake an opaque, muddy appearance. Stream 1 flows over its banks prior to exiting the golf course through a culvert under Bridgeway Drive. The existing culvert is inadequately sized to convey stream flows that arise during wet weather events. The seasonal flooding that occurs on the golf course property may help to reduce the sediment load downstream. During wet weather events unprotected streambanks in Stream 1 are more susceptible to degradation by the higher velocities.
Two wetland areas associated with Stream 2 tributaries are located at the northern site boundary near Joy Road. The western wetland area contains scrub/shrub habitat. The stream flow enters this wetland through a five-foot culvert pipe under Joy Road and disperses through the wetland area (no channel
within the wetland area). The eastern tributary of Stream 2 passes through a three-foot culvert under Joy Road and into an emergent wetland system with predominately cattail vegetation and non-native Phragmites grass. The flow within the eastern tributary was observed to be greater during dry weather conditions compared to the western tributary.
Another wetland area observed is located on community property bordering Climbing Way Drive. This wetland covers approximately one-third of an acre (about the size of a typical lot in Loch Alpine) and contains a variety of wetland species, including skunk cabbage, marsh marigold, cattail, and willow shrubs. Other small wetlands were observed along roadsides in association with drainage channels.
A number of small wetland areas are located intermittently along Boyden Creek and its tributaries on the golf course property. In general, these areas are composed of a mixture of woody and herbaceous vegetation and serve to provide wildlife habitat, course obstacles, and windbreaks within the course. Wetlands within and adjacent to the lake are discussed in the next section.
The Upper and Lower Lakes are impoundments of Boyden Creek, which were created in the 1920’s by construction of two roadway dams. The Upper Lake is approximately 10.8 acres in size with a maximum depth of approximately13.1 feet (depth to bottom of sediments) and has a volume of 88,157 cubic yards. Table 1 and Figure 5a illustrate information obtained from on-site sampling in 1999 and information provided by the Loch Alpine Lakes Committee. The Lower Lake is approximately 12.5 acres in size with a maximum depth of 15.4 feet to the bottom of sediments, and has a volume of 107,895 cubic yards (Figure 5b). Both lakes are deepest near the outlet structures. Wind and input from incoming streams allow only weak and temporary periods of thermal stratification (Davis, 1998).
Islands are located in both lakes. The largest island is located at the north end of Upper Lake. The island is a substantial feature within the lake and contains a mix of deciduous trees including boxelder, green ash, basswood, red maple, and large cottonwood trees. A smaller island is located at the north end of the Lower Lake. This island contains a dense thicket of woody vegetation. Shorelines of both islands appear to be stable and have minor erosion problems.
Nonpoint sources of sediment in storm water runoff have caused the lakes to become progressively shallower. Growth and decomposition of aquatic plants has further reduced water depth. This is increasingly evident in the shallow area at the north end of Upper Lake and along the western shoreline of the Lower Lake. The thickness of the sediment layer ranges from 1 to 4 feet in the Upper Lake and 1 to 5 feet in the Lower Lake (Figures 6a and 6b). It is likely that the sediments are high in nutrients that promote excessive growth of algae and vascular aquatic plants.
In 1994, analysis of the sediments and water was conducted. Sediments were analyzed for concentrations of pesticides, volatile organic substances and heavy metals (copper and mercury). Lake water was analyzed for concentrations of fecal coliform bacteria. Pesticides and volatile organic substances in the sediments of both lakes were not evident as indicated by levels that were below the detection limits. Concentrations of heavy metals and copper were higher in the Upper Lake than Lower. Levels of fecal coliform bacteria were well below the levels that would represent a human health hazard.
Table 1: Water and Sediment Depth Sampling in Upper Lake
(sampling conducted by JJR staff on September 8, 1999)
Sampling location |
Depth to top of sediments (water depth) |
Depth to solid bottom |
Sediment layer |
Description of sediment |
A |
1.5' |
3.5' |
2.0' |
black, organic fibrous material |
B |
1.2' |
1.7' |
0.5' |
silty sand |
C |
4.0' |
6.0' |
2.0' |
black, fine silty clay, slippery |
D |
2.5' |
4.5' |
2.0' |
black, silty, with a little sand grit |
E |
3.0' |
3.5' |
0.5' |
black, sandy clay |
F |
1.2' |
2.2' |
1.0' |
drop off 20' from the shore |
G |
11.0' |
> 12' |
undetermined |
sandy clay |
H |
3.2' |
4.2' |
1.0' |
sandy/silty clay |
Figure 5a: Water Depths- Upper Lake
Figure 5b: Water Depths- Lower Lake
Figure 6a: Sediment Depths- Upper Lake
Figure 6a: Sediment Depths- Upper Lake (continued)
Figure 6b: Sediment Depths- Lower Lake
In September 1999, during dry weather conditions, samples of sediment and lake water were collected within the Upper Lake and submitted to a local laboratory for chemical analysis (Table 2). Samples were analyzed for concentrations of nutrients including total phosphorus, nitrate nitrogen and total nitrogen. In general, the parameters were below the levels indicative of nutrient enrichment. This does not imply, however, that nutrients are not the cause of excessive growth of aquatic weeds and algae in the lake. It is possible that, between wet weather events, nutrient utilization by plants and algae could significantly reduce nutrient concentrations in the water column. Sampling during wet weather events would provide a more accurate assessment of nutrient concentrations. Analysis of a sample taken at location A (see Figure 5a), near the mouth of Boyden Creek, indicates that levels of phosphorus approach the State of Michigan Surface Water Quality Standard Limit of 5.0 mg/l. Although a more rigorous sampling effort would be needed to confirm that Boyden Creek is a major source of nutrient enrichment, initial information identifies this stream as a likely source of phosphorus loading.
Sediment samples were collected to confirm the opinion that the lake sediments are nutrient rich and promote excessive growth of aquatic weeds and algae. Analyses of sediment samples indicate that levels of phosphorus (38 mg/kg) fall outside the range (44 – 2,200 mg/kg) found in sediments collected from other locations within this region (MDEQ, 1999). However, the level of total nitrogen (2,433 mg/kg) is within the range (165 – 13,000) found in sediments collected from other locations within the region (MDEQ, 1999). The large range is indicative of the amount of variability found in sediments within the region. Nevertheless, the amount of phosphorus within the sediment is sufficient to produce the algae blooms and weed growth observed.
Qualitatively, water quality within the lakes is good with the exception of areas of stagnation. Stagnation within the north end of Upper Lake is causing conditions that impair aesthetics and the community of aquatic organisms. Blooms of blue green algae were observed at this location during site visits. This is a sign of nutrient rich sediment and anoxic conditions which promote the growth of this type of algae. Similar conditions exist along the western shoreline of Lower Lake; however, it does not appear as severe as in the Upper Lake.
Excessive growth of submergent aquatic plants including non-native weeds such as Eurasian water milfoil and curlyleaf pondweed evident throughout the perimeter of both lakes is reported to impair recreational activities and aesthetics during the summer months (Figure 7).
Treatment of algae and aquatic vegetation with herbicide occurs repeatedly during the summer months. A total of four separate treatments with aquatic herbicide were conducted during 1998. JJR representatives contacted Great Lakes Aquatic Weed Control (Mr. Ronald Berry) during the study to learn about on-going chemical treatment of aquatic weeds (milfoil, coontail, and curleyleaf pondweed) and algae within the two lakes. A Treatment Report was provided to JJR indicating the chemicals used in 1998 and also planned for use in 1999. Chemical treatment in 1998 included:
A permit was obtained from the Michigan Department of Environmental Quality (MDEQ) prior to the chemical treatment in the lakes. Of the chemicals used, only 2,4-D requires a restriction on swimming for one-day following its use.
Table 2: Water Chemistry and Sediment Analysis (see Figure 5a for sample location)
WATER CHEMISTRY |
SEDIMENT CHEMISTRY | ||||||||
Sample Location |
Dissolved Oxygen |
Conductivity |
PH |
Total Phosphorus (TP) (mg/L) |
Nitrate (NO3) (mg/L) |
Total Nitrogen (TKN) (mg/L) |
Total Phosphorus (TP) (mg/kg) |
Nitrate (NO3) (mg/kg) |
Total Nitrogen (TKN) (mg/kg) |
A |
7.4 |
540 |
7.3 |
1.60 |
<0.04 |
720.00 |
47.00 |
3.90 |
2000.00 |
B |
7.3 |
660 |
7.3 |
4.40 |
<0.04 |
970.00 |
31.00 |
2.00 |
2000.00 |
C |
10.0 at water surface 8.8 at top of sediment |
580 |
7.4 |
||||||
D |
12.6 at water surface 9.1 at top of sediment |
550 |
7.5 |
1.00 |
0.068 |
995.00 |
37.00 |
4.00 |
3300.00 |
E |
12.0 at water surface 13.0 at top of sediment |
540 |
7.6 |
||||||
F |
Analysis not conducted for this sample |
||||||||
G |
Analysis not conducted for this sample |
||||||||
H |
Analysis not conducted for this sample |
||||||||
Figure 7. Lake Area Existing Conditions/Analysis
Great Lakes Aquatic Weed Control uses a 16-foot boat with a pump and motor to mix the lake water with the chemicals. Great Lakes provides monitoring of treatment success. In 1999, treatment resulted in a temporary reduction of nuisance aquatic vegetation and algae. Unfortunately, by late summer, dense stands of Eurasian watermilfoil were evident in waters less than six feet deep in the Upper and Lower Lakes. Recent algae blooms resulted in mats of green and bluegreen algae at the north and south ends of the Upper Lake.
Loch Alpine lakes are host to a variety of aquatic life. Many residents report angling for several species of warmwater game fish including yellow perch, black crappie, largemouth and smallmouth bass, bluegill and pumpkinseed sunfish, and occasionally northern pike. During a site visit, creek chub, and Johnny darters were observed within Stream 1 approximately 200 feet upstream from its confluence with the Upper Lake. Largemouth bass and smallmouth bass were also observed within Stream 1 and both Upper and Lower Lakes. The shallow water area along the north shore of Lower Lake appeared to be heavily used by small fish and these areas probably serve as important nursery habitat. Removal of silt would probably expose firm substrate that would allow the area to serve as nursery and spawning habitat. Conversations with residents and subsequent site visits have identified spawning sites for bass along the northwest shore of the Lower Lake and the southeast shore of the Upper lake. The Redside dace, a state endangered fish species, was found in Boyden Creek in 1945 (Appendix C).
Aquatic macroinvertebrates were observed within the lakes and contributing waterways. These small organisms such as crayfish and dragonfly larvae serve as an important part of the food chain for the Loch Alpine aquatic ecosystem. Although a detailed survey of aquatic macroinvertebrates was not conducted, scuds, damselfly and dragonfly larvae, water beetles, water-striders, midge and mayflies were observed within the lakes. The Purple wartyback mussel, a state species of special concern is known to occur within the Huron River downstream of the confluence of the river with Boyden Creek (Appendix C).
Since 1993 the Huron River Watershed Council has conducted assessments of tributaries to the Huron River including Stream 1. During this period a total of 71 different taxa have been collected including several taxa that exhibit a low tolerance for environmental pollution (see Appendix D). In general, assessments indicate Stream 1 exhibits a healthy community of aquatic organisms, good water quality and is rated as one of the highest quality streams in the Huron River system (Martin, 1998).
Floodplain elevations surrounding the lakes are not identified on the Flood Insurance Rate Map prepared by the Federal Emergency Management Agency (FEMA, 1989). Personal communication with one of the lakefront owners indicates that the lake levels rise as much as three feet after a major storm event.
Relatively few wetland areas were observed in the vicinity of the lakes. Emergent wetland vegetation was observed along the channel of Stream 4 and within Upper Lake near the Loch Alpine Park shoreline. A small (less than 0.2 acre) emergent wetland is located within the northeast corner of the Lower Lake where Stream 5 flows into the lake. Emergent vegetation observed included iris, cattail, arrowhead, reed canary grass, swamp milkweed and blue vervain. A scrub/shrub area borders this wetland on the north and contains cottonwood, black cherry, willow, silky dogwood, honeysuckle, and buckthorn. A limited amount of wetland vegetation such as softstem bulrush was observed along the northern edge of the Lower Lake.
The Loch Alpine community is situated near areas of significant wildlife habitats associated with the Huron River corridor, Boyen Creek corridor and woodlands to the east, while the lakes themselves attract waterfowl and mammals as well. Residents commonly observe large mammals such as deer and fox along the lakefront. Muskrats inhabit the lake and were observed during the site visit. Other common mammals likely to inhabit the area include raccoon, skunk, opossum, Eastern and black squirrel, and Eastern Cottontail rabbit.
Migratory and resident waterfowl utilize the lakes. During the site visits mallards, Canada geese, and a Mute swan were observed. Residents report observing Wood duck in areas of woody vegetation along the shore of the lakes. A Mute swan was observed nesting within a more remote area of shoreline on Lower Lake. Residents report that this swan has returned to nest on the lake for approximately five years in succession. Canada geese use the common areas preferring to feed on the turf grass located there.
Painted turtles and bullfrogs were observed near the small island within Lower Lake. Other amphibians and reptiles likely to inhabit the lakes and wetlands of Loch Alpine include green frog, wood frog, chorus frog, snapping turtle, garter snake, and northern water snake.
Most of the lake edge is vegetated with a mix of deciduous trees, mature evergreen plantings, lawns, and non-native shrubs such as common buckthorn and honeysuckle. These invasive large shrubs diminish views of the lakes from lakefront properties, roads, and parkland within Loch Alpine during warm weather months and discourage the growth of native groundcovers and young tree seedlings by creating a dense shade layer within the woodland understory. Most native woodland understory shrubs and small trees such as alternative leaf dogwood, serviceberry, and mapleleaf viburnum have more stratified branching patterns and leaf out later than non-native shrubs, which permit light to penetrate to the woodland ground layer. Native groundcover plants such as mayapple, bloodroot, Pennsylvania sedge, wild geranium and trillium require a more open understory to thrive well.
Shrubs and trees were recently removed along the eastern shoreline of Lower Lake, to protect the roadway dam stability.
Non-native invasive purple loosestrife (a herbaceous plant with bright purple flowers in July) was observed in a few areas; however, it is not currently a major concern along the lake edge. Monitoring, hand removal, and proper disposal of this species is currently the best method to control its growth.
Lawns maintained up to the edge of the lakes encourage waterfowl such as Canada geese to feed and rest along the lake edge. The shallow roots of turf grass species also do not prevent the wave action of the shoreline waters from eroding the banks.
Land use surrounding the two lakes consists of residential lawns, maintained parkland, and naturalized areas on community owned property. A strip of community land of varying width rings the two lakes; however, many residents maintain the strip as part of their lawns and a specific line of demarcation between community and private property is not apparent. Small boat storage was observed in numerous locations surrounding both lakes. A total of 29 households border the lakes and of this total only 20 have convenient direct access to the lakes. Many more households, however, most likely have views of the lake or the potential for views with selective clearing of non-native vegetation along the lake edge.
Several common areas exist adjacent to the lake. Loch Alpine Park located on the western shore of the Upper Lake is a large community resource with a number of amenities including a new play structure, picnic tables and grills, volleyball net, and a ball diamond. The park is used informally by Loch Alpine residents and collectively during the 4th of July festivities. Brush piles are burned within the park during the spring and fall. The low-lying areas of the park are often unpleasant during warm weather due to mosquitoes, and the former swimming beach area is unused due to excessive aquatic weed growth, a mucky shoreline bottom, and abundance of goose droppings along the shoreline. Several groundwater seeps were observed along the drainage channels within the park.
Pedestrian access to the park is provided by a series of wooden steps adjacent to Loch Alpine Drive West and vehicular access is obtained from Bridgeway Drive. The lack of a pedestrian ramp from Loch Alpine Drive makes stroller access difficult.
Rock Park, located on the northern shoreline of the Upper Lake, is the second largest common space within the community (with the exception of the wastewater treatment area). Rock Park contains a meandering section of Boyden Creek and a filled area that is stabilized with turf grass. Relatively little use of this park was observed during site visits with the exception of boat storage.
A third common space area is located near Rock Park and is easily accessed (both pedestrian and vehicular) from Woodland Drive. This wooded site contains an open understory and is also used for boat storage. An excessive amount of algae and aquatic weed growth was observed along the shoreline at this location, which is adjacent to the large island. The island is ringed by steep side slopes and a drainage channel. Access to the island is obtained with difficulty (across a debris pile) during low water level conditions.
A little used common space area is located at the end of Greenook Boulevard. This area is landscaped with mature evergreen trees near the road, which prohibit views of the Lower Lake from the road. Between the road and lake edge, the topography drops fairly quickly. The area is currently used for storage of brush piles.
West of Greenook Boulevard is a fairly wide low-lying common space that is densely vegetated with tall shrubs and trees. A narrow pathway extends into this area but disappears into the brush. The area was traversed by JJR representatives and could potentially be improved to provide pedestrian access between Greenook Boulevard and the wooden steps near the inlet point to the Lower Lake. Additional recommendations are discussed later in this document. The steps provide fishing and viewing access from the Midway Drive bridge. A wood guardrail adjacent to the lake edge is needed. Use of this area by anglers was observed on several site visits.
A primary boat storage area exists within common space between Midway Drive and the northwestern shoreline of Lower Lake. This turf grass area serves as an emergency spillway for the Upper Lake during flooding events.
The northeastern common space area bordering the Lower Lake is not readily accessible to Loch Alpine residents. The low-lying, densely vegetated area is only accessible from the backyards of a few properties. Nesting waterfowl, as discussed above under Wildlife, use this area.
The purpose of developing goals and objectives during the scope of this feasibility study was to provide direction for the study and a means of measuring the success of future activities intended to respond to those goals and objectives. A survey of Loch Alpine residents taken in 1993 provided the foundation for the development of goals and objectives regarding rehabilitation of the lakes. Additional information obtained from a July 1999 meeting with the Loch Alpine Lakes Committee influenced the drafting of goals and objectives for not only lakes rehabilitation, but also long-term storm water management and enhancement of the lakes area as a recreational amenity for the Loch Alpine community.
Understanding the processes that have led to the need for rehabilitation of the lakes is important to the selection of alternatives and future long-term management. Eutrophication and sedimentation are two processes that have led to impairment of the lakes. Eutrophication is the process by which lakes are fertilized with nutrients, which are used for the growth of rooted aquatic plants and algae. Eutrophication is a natural aging process in lakes. Under natural conditions, nutrients such as nitrogen, potassium and phosphorus are contributed to a lake from surface water runoff and eroded soil. Over a span of centuries, growth and decomposition of aquatic plants may cause a lake to fill in and become a marsh or a bog. Human activities such as farming, maintenance of lawns and golf courses, air pollution and nutrient contributions from excessive numbers of waterfowl can contribute exorbitant amounts of nutrients resulting in dense growths of aquatic plants. By accelerating the natural process of eutrophication, the time required for a lake to fill in is reduced from centuries to decades. This process termed “cultural eutrophication” is what has, and is, occurring in the Upper and Lower lakes.
The second process affecting the lakes is called sedimentation. Erosional forces of wind and water transport soils from a surrounding watershed down to a lake. These soils, commonly called sediment, settle on the bottom of a lake and the lake becomes increasingly shallow. This process of sedimentation is a natural part of lake aging and is governed by gravity and forces of wind and rain. Sedimentation is greatly accelerated by human activities that leave soils exposed for extended periods of time. This process exceeds cultural eutrophication in its ability to reduce depths of lakes. Since the construction of the Loch Alpine lakes, land development has increased soil erosion within the watershed resulting in increases in turbidity, increases in the rate of sedimentation during wet weather events, and decreases in lake depths.
The processes of sedimentation and cultural eutrophication have led to the aesthetic and recreational impairments evident in the Upper and Lower lakes, necessitating the investigation and implementation of lake rehabilitation activities.
The process of cultural eutrophication can significantly reduce the lifetime of a lake causing open water to be replaced by aquatic plant growth. In the absence of an integrated program for in-lake rehabilitation activities and storm water management practices, the following would be expected to occur:
The in-lake problems can be reduced by a number of different rehabilitation techniques as discussed in this section. Table 3 summarizes the various techniques that have been considered for improving the Loch Alpine lakes.
Table 3: Techniques that have been considered for improving the Loch Alpine lakes
ALTERNATIVES |
BENEFITS |
CONSIDERATIONS | |||||||||||
Recreational Use |
Aesthetics |
Water Quality |
Wildlife Habitat |
Lake Access |
Impacts to Infrastructure |
Impacts to Huron River |
Cost (2) |
Maintenance |
Duration of Improvement |
Predictability of Success |
Recommendation (3) | ||
Physical Measures | |||||||||||||
|
Dredging(1) |
High - Improved conditions for boating, swimming and fishing |
High - Improved appearance of lake surface and shallow water areas |
High - Removal of nutrient rich sediments decreases amounts of nutrients within the lake system and reduces or eliminates algae blooms |
Moderate – Shallow water habitats may be eliminated during sediment removal reducing habitat diversity |
Low - No change in access |
High - Condition of existing roads may be degraded |
Moderate. – Sediment discharge during dredging must be controlled |
High |
Low |
Long-term |
Moderate - Dependent on concentration of nutrients in newly exposed lake bottom |
Recommended | |
|
Alteration of Lake Bottom Contours |
Moderate - Improvements for boating. swimming and fishing limited to new deep areas |
Moderate - Improved appearance of lake surface in deeper areas. |
None - No removal of nutrient rich sediments |
High - Bottom variability provides a diversity of habitat for fish and waterfowl |
High - New points of access can be created by piling and stabilizing regraded sediment to extend existing shoreline. |
Low - limited disturbance to lake edge at points of access |
Moderate. – Sediment discharge during grading must be controlled |
Moderate – requires dewatering |
Moderate - Nutrients are not removed from sediment and treatment of nuisance plants and algae will continue to be required |
Short-term |
Moderate – Dependent on concurrent application of other restoration techniques |
Recommended | |
Aeration |
Moderate - Improvements for fishing, boating and swimming limited to new deep areas. |
Moderate - Improvements aesthetics will be contingent upon removal of existing stands of nuisance aquatic vegetation |
High – Increases dissolved oxygen supports decomposition of organic matter in bottom sediments. |
High - High levels of dissolved oxygen can improve fish community. |
None |
Low - requires electrical connection |
None |
Moderate - Initial purchase and installation fees incurred and will require continual electricity during the growing season |
Moderate - Pumps will require routine maintenance. |
Short-term |
Low - When applied to whole lake treatments greater than five acres |
Recommended | |
Dilution and Flushing |
Moderate - Improvements for boating, swimming and fishing will be contingent upon removal of existing stands of nuisance aquatic vegetation |
Moderate – Improvements aesthetics will be contingent upon removal of existing stands of nuisance aquatic vegetation |
High - Method reduces nutrient concentrations within the lake system. Water clarity improvements may occur, but are dependent on the volume and clarity of the water input. |
Moderate – Improved water clarity and quality |
None |
None |
None |
Low - if water comes from a natural source Moderate – if artificial water source is needed. |
Low - if water comes from a natural source Moderate - if artificial water source is needed. |
Long-term |
High |
Not Recommended | |
Drawdown |
High - improved conditions for fishing |
High - Improved appearance of lake surface and shallow water areas. |
None - No removal of nutrient rich sediments. |
Moderate - method impacts native and non-native flora and fauna. |
None |
None |
None |
Moderate – Drawdown evacuation of fish species may require restocking of gamefish |
Moderate - for optimum results this method may need to be repeated bi-annually |
Short-term |
Moderate – Dependent upon duration of drawdown and composition of the existing plant community. |
Recommended | |
Harvesting |
High - although short lived. method will result in improved conditions for boating, swimming and fishing |
High - although short lived, method will result in improved appearance lake surface. |
None |
Low - Benefits to wildlife habitat are minimal and short lived. |
None |
None |
None |
Low |
High - method may require implementation two to three times during the growing season |
Short-term |
Low - Repeat treatments |
Not Recommended | |
Bottom Sealing |
Moderate - Improvements for boating, swimming and fishing will be contingent upon removal of existing stands of nuisance aquatic vegetation |
High - Improved appearance of lake surface and shallow water areas |
High - Improves water clarity and prevents recycling of nutrients in sediments. |
Moderate - may inhibit certain important biological processes on the lake bottom. |
None |
None |
None |
Moderate |
Low |
Long-term |
Low - In shallow lakes the bottom seal can be disrupted. |
Not Recommended | |
Shading |
Moderate - improvements for boating, swimming and fishing will be limited to shaded areas |
Moderate - will eliminate nuisance growth of aquatic vegetation, but will not eliminate mats of floating algae |
None - No removal of nutrient rich sediments. |
None |
None |
None |
None |
High |
High - materials used to cover the lake bottom are expensive. |
Short-term |
High |
Not Recommended | |
Chemical Measures | |||||||||||||
Herbicides & Algaecides |
High - Kills aquatic weeds |
High - Kills aquatic weeds |
Moderate -Improved Water clarity, but no reduction in nutrient concentrations. |
Moderate - accumulation of copper in sediments may result from long-term use and can lead to impairment of aquatic communities |
None |
None |
None |
Low |
Moderate - repeat treatments are necessary. |
Short-term |
High |
Recommended | |
Biological Measures | |||||||||||||
Herbivorous Aquatic Insects |
High for rooted aquatic vegetation, No impact on algae |
High |
Moderate – Improved water clarity, but no reduction in nutrient concentrations. |
High |
None |
None |
None |
Low |
None |
Long-term |
Moderate – Dependent on the number of aquatic insects introduced and their survival. |
Not Recommended | |
Ocean Arks “Lake Restorer” |
High |
High |
Moderate - The structure itself may provide habitat for aquatic insects and fish. |
High |
None |
Low – may require electrical connection |
None |
High |
Moderate |
Long-term |
Unknown |
Undecided | |
(1) Assuming 75% of lake bottom dredged and the majority of sediments are disposed of off site. |
|||||||||||||
(2) High Cost (>$100.000): Moderate Cost ($20.000 - $100.000): Low Cost (<20.000). |
|||||||||||||
(3) Assuming the recommended alternative activity is conducted in combination with dredging and stormwater management activities. |
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Removal of lake sediment is usually undertaken to deepen a lake thereby increasing its volume to enhance recreational uses such as boating and swimming and to improve aesthetics, fish production, or to remove nutrient rich sediment, toxic or hazardous material, and excessive stands of submergent aquatic plants. The technique is recommended for deepening and for reducing phosphorus release from sediment. Removal of nutrient laden sediment can be conducted with minimal environmental impact when proper equipment is used, but it may be extremely expensive. In addition, dredging will remove submergent aquatic plants, however, their rate of re-growth will depend on the conditions of the lake bottom after dredging including sediment texture, slope and concentration of nutrients. Often the cost of sediment removal and disposal is prohibitive.
Alteration of lake bottom contours consists of changing the lake bottom to increase or decrease depth of the lake at certain locations. This typically involves draining the lake and re-grading bottom sediments. Control of nuisance aquatic weeds can occur in areas that are made sufficiently deep. Because this alternative involves redistribution and not reduction of sediments, efforts to control algae will likely continue in remaining shallow water areas. Aesthetic improvements are likely to be greatest in areas where the lake has been sufficiently deepened.
Artificial aeration can eliminate or prevent thermal stratification, through the injection of compressed air into the lake from a pipe or ceramic diffuser at the lake's bottom. This can greatly reduce the chemical processes that cause migration of nutrients from bottom sediments into the water column, and as a result, eliminate or reduce the occurrence of algae blooms. Success of this method has been unpredictable and is difficult to implement on water bodies greater than five acres.
Dilution/flushing has been documented as an effective rehabilitation technique for Moses Lake and Green Lake in Washington State. The dilution water added in both lakes was low in nutrient content relative to the lake or normal input water. Flushing rates were about ten times normal during the spring-summer periods in Moses Lake and three times normal on an annual basis in Green Lake. Improvement in quality (reductions in nutrients, algae, and increases in transparency) was on the order of 50 percent in Moses Lake and even greater in Green Lake. Long-term improvement is dependent on a lake receiving sufficient quantities of well-oxygenated, low nutrient water.
Draining water from a lake and exposing sediments to prolonged freezing and drying for approximately two to four weeks results in permanent damage to certain rooted plant species, but the technique is species-specific. Density of coontail, milfoil, water lily and Robbin’s pondweed decrease, while bushy pondweed may increase and common elodea may not respond at all. This is a fairly short-term solution due to the fact that nutrients in the sediment remain and can support re-growth of aquatic plants in three to five years after the drawdown.
Harvesting is a method used to reduce nutrients by manually or mechanically removing algae and plants from a lake. In lakes that contain excess nutrients in the sediments or receive nutrient rich storm water the amounts of nutrients removed in the form of plant materials is insignificant. This method is primarily considered a short-term, cosmetic improvement similar to mowing a lawn.
This method uses chemicals such as alum and calcium nitrate to inactivate nutrients in sediment by forming compounds that cannot be utilized by algae and submergent aquatic plants. In shallow lakes, currents from wind and recreational activities can compromise the integrity of the bottom seal. Foraging activities of bottom feeding fish can also break the seal and allow for a release of phosphorus. The Michigan Department of Environmental Quality (MDEQ) does not recommend this method due to its unpredictability of success (MDEQ, 1990).
Sediment covering materials are used to stop plant growth by inhibiting root establishment and light penetration. Because the materials are expensive, use is often limited to small areas such as dock spaces and swimming beaches. Shade tolerant species have been known to survive these light limited conditions. Commonly used materials and effectiveness are as follows:
Black Polyethylene • Application Difficulty: High • Comments: Poor choice of materials, easily dislodged and "balloons" Polypropyl (Typar) • Application Difficulty: Low • Comments: Effective Fiberglass PVC (Aquascreen) • Application Difficulty: Low • Comments: Effective |
Nylon (Dartek) • Application Difficulty: Moderate • Comments: Effective if vented Burlap • Application Difficulty: Moderate • Comments: Effective up to one season: rots Nylon- Silicone • Application Difficulty: Unknown Comments: Must be installed by dealer |
Presently, this technique is being conducted on an annual basis within the lakes. This is a short-term technique that treats the symptoms but not the source of the impairment. This method uses herbicide toxic to either a broad group of aquatic plants or specific plants. Typically, repeat treatments must occur to obtain the desired aesthetic improvement. Late summer observations indicate a significant amount of aquatic vegetation exists at the end of the growing season.
Insects have been introduced with some success to selectively feed upon aquatic plant populations. Larvae of aquatic moths and weevils have been introduced where exotic plant populations have become established. The degree of success is dependent on the number and survival of insects introduced and how effectively they colonize the remainder of the lake (Carr, 1999). It can take several years to realize the benefits of this method, however, when combined with consistent monitoring and maintenance of control organisms long-term effectiveness has been obtained.
This is a manmade structure that floats on the surface of a lake or pond. The Lake Restorer technology uses the ability of naturally occurring plants and bacteria to remove excess nutrients from the water and sediments. The structure consists of a core cell containing plastic media that supports growth of nutrient consuming bacteria and a platform, surrounding the core cell that contains nutrient consuming plants. Water is lifted from the bottom of the lake into the core cell and from the core cell into the surrounding platform and then back into the lake. This results in a two-stage process of nutrient removal and addition of oxygenated water to the lake. The Lake Restorer does not remove sediments; therefore, this option would not create deeper water habitat for fish.
The technique of dredging sediments from the lake received considerable analysis as part of this Feasibility Study because it is most likely to: 1) reduce the concentration of released nutrients from the lake bottom; 2) increase depths and overall volume; and 3) result in immediate aesthetic and recreational improvement. When combined with dredging, methods including alteration of the lake bottom, aeration, drawdown, and limited herbicide application can enhance the short-term success of the lake rehabilitation and aid in the long-term management of the lake. With the exception of the Lakes Restorer, other techniques identified above would be of limited benefit to Loch Alpine, although methods such as shading or harvesting could be applied on an individual basis. Additional review of the Lakes Restorer is needed to determine the feasibility of this technique for improving water quality in the lakes.
The 13th Edition of RSMeans’ Heavy Construction Cost Data (1999) was used to compare the different methods available for removing the sediment from Upper and Lower Lakes. Three different types of earth removal were analyzed, including, dredging, bulk bank measure excavating and bulk dragline excavating. An Earth Removal Cost Estimate (Appendix E) was developed to more easily compare the different methods. The costs and times to completion were broken down for each excavation method, as well as for several different amounts of sediment to be removed.
Several different types of dredging equipment are available to remove the sediment from the lakes. Essentially they are broken down into barge-mounted clamshells or draglines and hydraulic pumping. The clamshells or draglines mechanically remove the soil from the bottom of the lake and deposit it into a scow. A scow is a large, flat-bottomed boat that would allow for the soil to be pumped or transported to the shore. The hydraulic pump extracts the wet soil from the bottom of the lake and either deposits it into a scow for transport or continues pumping it to the shore. The values shown in the Earth Removal Cost Estimate are given as minimums and maximums. The cost of the dredging operation will depend on the properties of the soil. Harder soils are more difficult to remove and therefore would tend to cost more than soft soils which are easier to remove. Since the sediment to be removed is near the surface and observed to be relatively soft, the cost will tend toward the minimums.
Bulk bank measure excavating can be accomplished using several different machines. These consist of backhoes, clamshells, front-end loaders, and shovels. Many different sizes are available for each of these machines. The values shown in the Earth Removal Cost Estimate show how the cost and time for completion varies for the different types and sizes.
Bulk dragline excavating is accomplished using a single type of machine. Different size buckets are available, and the productivity of the machine is relative to the type of soil to be removed. The values shown in the Earth Removal Cost Estimate show the different sizes available, as well as how the cost and time to completion varies with the soil type.
As can be seen in the Earth Removal Cost Estimate, the bulk bank measure excavating techniques provide the most cost efficient methods of earth removal. However, both of the bulk excavating methods involve drawing down the water surface of the lakes, and this extra cost must be considered.
Sediment testing should be conducted to determine the quality of the sediment for reuse. Potential re-use opportunities to be considered include engineered fill, regular fill, or topsoil.
Several different sizes of dump trucks are available for transporting sediment from one place to another. In order to minimize the negative impact on the existing roads, smaller trucks were analyzed. The Hauling Cost Estimate (Appendix E) was developed to compare the different vehicles.
The site for the dumping of the excess sediment is undecided. Consequently, the round trip distance for the dump trucks is unknown. For this reason, several different travel distances were used for each size vehicle. A separate column was added with a larger number of trucks. This will reduce the number of days necessary to complete the hauling without increasing the cost of the operation. The number of trucks can be matched to the number of days for the completion of the excavation so that they will finish concurrently.
In order to remove the excess sediment that has built up in Upper and Lower lakes, both of which lie within the Loch Alpine neighborhood, a series of dump trucks may have to traverse the on-site roads. These roads were not designed for this type of loading. Therefore, it is necessary to determine the level of impact that will occur to the roads within the Loch Alpine neighborhood. The AASHTO Guide for Design of Pavement Structures (1986) was used for this analysis.
Review of construction drawings for the site reveal that the existing road cross section is as follows:
Figure 3.1 from the AASHTO Guide (Appendix E) was used to determine the design characteristics of the existing pavement section. The following parameters were defined in Division II, Section 7I, of the City of Ann Arbor Design Standards:
Since the traffic that will traverse a roadway will be made up of several different types of vehicles, a standard was developed to simplify the design process. The standard is the 18-kip Equivalent Single Axle Load (one kip equals 1,000 pounds). A vehicle smaller than 18-kips will have less of an impact on the roadway. Therefore, it is given a reducing coefficient. The opposite can be said for vehicles larger than 18-kips.
In order to determine the Total 18-kip Equivalent Single Axle Load Applications, W18, that the on-site roadways were designed for, the Structural Number, SN, for the pavement section and the Effective Resilient Modulus, MR, of the sub-grade must be calculated. The following equation can be used to calculate the Structural Number:
In this equation, ai represents the layer coefficients and Di represents the layer thickness. These are multiplied and summed over the number of layers to determine the Structural Number. The layer coefficients, which depend on the material used in each layer, were also defined by the City of Ann Arbor Design Standards as follows: