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Mitigation Projects > Artificial Reef > Mitigation Phase

[Artificial Reef] Mitigation Phase

  • Planning & Construction
  • Performance Standards
  • Monitoring & Evaluation

Planning and Construction

map of 18 polygons and 56 experimental modules table of  18 polygons and 56 modules
Map of the 18 polygons and 56 experimental modules that comprise the 174 acre Wheeler North Reef.   Acreage and number of long-term monitoring transects for the 18 polygons and 56 experimental reef modules of the Wheeler North Reef.

On April 17, 2006 the California State Lands Commission acting on a request from SCE adopted a resolution declaring that the SONGS Mitigation Reef be named in honor of Dr. Wheeler North. The design for the Wheeler North Reef proposed by SCE and approved by the California Coastal Commission was a low-profile, single-layer reef (< 1 m in height) of quarry rock distributed on the sea floor in quantities similar to those of the lowest substrate coverage used in the experimental phase (i.e. 43%).  Approximately 126,000 tones of boulder-sized quarry material were deposited in 18 polygons that vary in area from 1.35 to 38.8 acres. When added to the 22.4 acre experimental reef a total of 174.4 acres of mitigation reef were constructed.

skip loader   constructing the Wheeler North Reef
A skip loader prepares to dump quarry rock during the construction of the Wheeler North Reef. Constructing the Wheeler North Reef.

Construction of the Wheeler North Reef began on June 9, 2008 and was completed on September 11, 2008. The dimensions of the quarry boulders used to construct the reef averaged 2.3 ft in length, 1.8 ft in width, and 1.4 feet in height. The boulders were hauled to the construction site by barge and precisely cast upon the seafloor within the described boundaries of each polygon in roughly a single-layer. The variation of boulder deposition per polygon ranged from 743 to 987 tons per acre with an average of 829 tons per acre. Post construction surveys using multi-beam sonar and divers verified that the Wheeler North Reef achieved the following desired objectives: 1) all polygons were built in close proximity to the San Mateo Kelp Bed; 2) all polygons avoided existing hard substrate areas that had historical presence of kelp; 3) the integrity of the Phase 1 Experimental Reef modules was maintained; 4) navigation channels were provided in response to concerns raised by fisherman; and 5) all constructed reef polygons avoided areas of historical kelp growth as well as areas of special interest to local fisheries.

   

 

Performance Standards

The SONGS permit requires that the following performance standards be used to measure the success of the Wheeler North Reef and to determine whether remediation is necessary.

  1. The mitigation reef shall be constructed of rock, concrete, or a combination of these materials.
  2. The total area of the mitigation reef (including the experimental reef modules) shall be no less than 150 acres.
  3. At least 42% but no more than 86% of the mitigation reef area shall be covered by exposed hard substrate.
  4. At least 90 percent of the exposed hard substrate must remain available for attachment by reef biota.
  5. The artificial reef(s) shall sustain 150 acres of medium-to-high density giant kelp.
  6. The standing stock of fish at the mitigation reef shall be at least 28 tons.
  7. The resident fish assemblage shall have a total density and number of species similar to natural reefs within the region.
  8. Fish reproductive rates shall be similar to natural reefs within the region.
  9. The total density and number of species of young-of-year fish shall be similar to natural reefs within the region.
  10. Fish production shall be similar to natural reefs within the region.
  11. The benthic community (both algae and macroinvertebrates) shall have coverage or density and number of species similar to natural reefs within the region.
  12. The benthic community shall provide food-chain support for fish similar to natural reefs within the region.
  13. The important functions of the reef shall not be impaired by undesirable or invasive benthic species (e.g., sea urchins or Cryptoarachnidium).
sandbass kelp forest invertebrates understory macroalgae in a giant kelp forest
Sandbass (Paralabrax nebulifer) on the newly constructed Wheeler North Reef (left). An assemblage of common kelp forest invertebrates in southern California (middle). An assenblage of understory macroalgae in a giant kelp forest (right).
UCSB diver measuring size and density of giant kelp
UCSB diver measuring the size and density of giant kelp during annual performance monitoring. Photo by Richard Herrmann

Monitoring and Evaluation

The SONGS coastal development permit requires monitoring by independent scientists be done during the mitigation phase to: (1) determine whether the performance standards established for the mitigation reef are met, (2) determine, if necessary, the reasons why any performance standard has not been met, and (3) develop recommendations for appropriate remedial measures. The Permit also requires the scientists to develop a monitoring plan for the mitigation reef that describes the sampling methodology, analytical techniques and methods for measuring performance of the mitigation reef relative to the performance standards identified in the SONGS coastal development permit. UCSB scientists produced a monitoring plan for the Wheeler North Reef that contains: (1) a description of the process that will be used to evaluate condition compliance, including a list of 13 performance standards by which the mitigation reef will be judged and the general approach that will be used to determine the overall success of the mitigation project, (2) descriptions of the specific sampling methods and analyses that will be used to evaluate each of the 13 performance standards, (3) an explanation of how project data will be managed and archived for future use, and (4) a description of how the results from the monitoring program will be disseminated to the CCC, SCE, and all other interested parties.