1. Project Title: Effects of Beach Nourishment on the Nearshore Environment, Lexington Harbor, Lake Huron
2. Contact
Thomas A. Edsall
Project Officer, Lexington Project
National Biological Service, Great Lakes Science Center (NBS-GLSC), 1451 Green Road, Ann Arbor, MI 48105, USA
Tel.: (313) 994-3331 ext 235; FAX: (313) 994-8780; E-mail: (cc-mail) R8 NFRC.GL
3. Agencies Involved
U.S. Army Corps of Engineers, Coastal Engineering Research Center, Kingman Building, Fort Belvoir, Virginia 22060, USA
National Biological Service, Great Lakes Science Center (NBS-GLSC), 1451 Green Road, Ann Arbor, MI 48105, USA
4. Restoration Goal
Mitigate beach erosion attributable to the installation of a small
watercraft harbor of refuge, which interrupted alongshore movement
of sediments and created sediment-starved beaches on
prevailing downcurrent side. Assess effects of beach nourishment
project on nearshore aquatic biota and habitats.
5. Project Type
Move accumulated beach sediments on upcurrent side of harbor to sediment-starved beaches on down current side; also nourish starved beaches with sediments of similar composition from a nearby borrow site on land. Conduct a "before and after" study of the project area to determine the short-term effects of the beach nourishment project on the nearshore aquatic biota and habitats.
6. Background and Rationale
In the late 1970's the U.S. Army Corps of Engineers (Corps) constructed a harbor of refuge for small watercraft on the shoreline of Lake Huron at Lexington, Michigan. The harbor provided the required shelter for small craft but also interrupted alongshore transport of sediment. This disruption of sediment transport created a sediment accretion area on the north side of the harbor and caused the beach to expand lakeward while starving the beaches to the south and causing them to recede landward to the base of the headland. The Corps designed a beach nourishment project to restore the beach-face profile north and south of the harbor to near pre-harbor condition and asked NBS-GLSC (then the U.S. Fish and Wildlife Service-Great Lakes Fishery Laboratory) to monitor the project for effects on nearshore aquatic biota and habitats. The nourishment project and the assessment study were performed in the early 1980's.
7. Regulatory Considerations
The Corps was the permitting agency and they contracted the nourishment work and the biological assessment. The Fish and Wildlife Coordination Act provided for project review by the U.S. Fish and Wildlife Service.
8. Criteria
Restore nearshore lake bed and beach front on both sides of the harbor to near-normal conditions as determined from adjacent reference areas and anecdotal site information that preceded harbor construction; cause no significant adverse impact on aquatic biota or habitats in the project area; and restore affected areas to near-normal condition.
9. Project Design
The Corps designed the beach nourishment project. The NBS-GLSC designed the "before and after" study that assessed project effects. The assessment study was conducted along an 8.4 km segment of shoreline roughly centered on the harbor. Aerial photography was used to document changes in the shoreline and the beach-face profile. Physical and biological data were collected at preset time intervals (June-October 1980, before and during project; and June-November 1981, after project) and at preset depth intervals, on four transects extending from the shoreline to the 5 m depth contour. Physical data collected were sediment grain size, suspended particulate matter, turbidity, temperature, and dissolved oxygen level. Biological data collected were kinds and numbers of macrozoobenthos, and kinds, numbers, and sizes of fish.
10. Implementation
The transport and placement of beach nourishment sediments occurred in October 1980. About 54 000 m3 of sediment was moved from the shoreline accretion site on the north side of the harbor to the shoreline nourishment site on the south side of the harbor; an additional 19 000 m3 sediment was trucked to the nourishment site from a nearby commercial borrow site on land. The assessment study lasted about 3 years. The field portion of the study extended from June 1980 to November 1981. The field work was performed from the shoreline and from a small boat. Weather and sea conditions controlled the work schedule particularly in the fall when storms were common. Macrozoobenthos sample reduction and analysis was typically labor intensive.
11. Degree of Environmental Intervention
The beach sediments and those from the borrow site were excavated and moved by land to the nourishment site with large equipment, including trucks. Bulldozers were used to spread the sediments along the beach front. Additional details may be available from the Corps. Some local, minor increases in turbidity probably occurred during the excavation of beach sediments and the deposition and spreading of sediments in the starved beach area. The lakeward extension of the shoreline in the sediment-starved area may have displaced some aquatic organisms, but the total effect, if any, was probably minor because the biota in the surf zone on this exposed beach were highly mobile (fishes), sparse (large benthic invertebrates), or adapted to life within wet sediments (psammon).
12. Cost
We have no estimates of the cost of the beach nourishment project.
The Corps may be able to provide them. Assessment costs covered
under the contract with the Corps were approximately
$50 000.
13. Biological Assessment
A 2 year before and after study with preselected effect and reference areas was performed. The study involved measurement of physical and biological variables in the study area. The study protocol and results are detailed in a published report (see item 15 below).
14. Measures of Success
The nourishment project was completed as planned. The assessment was completed as planned and demonstrated that the beach nourishment project had no major adverse effect on substrate particle-size distribution, water quality, macrozoobenthos, or fish in the study area. Marked changes in the shoreline and beach-face profile occurred in the immediate vicinity of the harbor as a result of the nourishment activity. However, the only obvious change that persisted 14 months after the nourishment project was completed (i.e., in November 1981 when the field portion of the assessment study was completed) was a moderate lakeward extension of the shoreline in the area immediately south of the harbor.
Success Rating: 4
The project was successful as designed. The project site is in a hydrodynamically dynamic zone and, therefore, the study would have benefited from assessment of longer duration to document annual physical and biological variation.
15. Key References
The effects of the beach nourishment project on the beach face and shoreline and all aspects of the assessment study are detailed in:
Nester, R.T., and Poe, T.P. 1982. Effects of beach nourishment on the nearshore environment in Lake Huron at Lexington Harbor (Michigan). U.S. Army Corps of Engineers, Coastal Engineering Research Center Miscellaneous Report No. 82-13, Springfield, Virginia.
The report is presumably available from the National Technical Information Service in Washington, DC.
Correct citation for this contribution:
Edsall, T.A. 1995. Effects of beach nourishment on the nearshore environment, Lexington Harbor, Lake Huron, p. 259-262. In J.R.M. Kelso and J.H. Hartig [editors]. Methods of modifying habitat to benefit the Great Lakes ecosystem. CISTI (Can. Inst. Sci. Tech. Inf.) Occas. Pap. No. 1.