Maryland Department of Natural Resources

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Harris Creek Restoration

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Large-scale restoration efforts began in 2011 in Harris Creek sanctuary. The initial phase of the restoration project was completed in 2015, with a total of 348 acres of reef restored. All six-year monitoring has been completed.

The restoration plan for Harris Creek can be found here. View the Harris Creek Story Map. 
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The oyster metrics are quantitative evaluation criteria used to determine the restoration success of an oyster reef and tributary.

  • A successfully restored reef should have:
    • A ‘minimum threshold’ of 15 oysters and 15 grams dry weight per square meter covering at least 30 percent of the target restoration area at six years post restoration;
    • A ‘target’ of 50 oysters and 50 grams dry weight per square meter covering at least 30 percent of the target restoration area at six years post restoration;
    • Two or more oyster year classes present; and
    • Stable or increasing spatial extent, reef height, and shell budget.
  • A successfully restored tributary is one where:
    • 50 to 100 percent of the currently restorable oyster habitat (CROH) has oyster reefs that meet the reef-level metrics above. Restorable habitat is defined as area that, at a minimum, has appropriate bottom quality and water quality for oyster survival AND
    • ​8 to 16 percent of historic habitat (Yates Bars), and preferably more, has oyster reefs that meet the reef-level metrics above

Three-year and six-year monitoring efforts are used to assess the oyster metrics for each reef.

Per the success criteria established in Oyster Metrics, and the Harris Creek Tributary Plan, the Harris Creek tributary can now be considered fully, successfully restored.

As of fall 2021, all 90 restored reefs (348 acres) in Harris Creek have been monitored as they matured to six years—the point where, per Oyster Metrics, a reef can be considered successfully ‘restored’ if it meets all the Oyster Metrics success criteria. Harris Creek is the first tributary where the recommended six-year monitoring period has been completed.
The restoration plan called for between 300 and 600 acres of reefs to be restored (per Oyster Metrics criteria) for Harris Creek to be considered fully restored. A total of 348 acres of reefs have received restoration treatment. Of those, 343 acres of reefs can be considered successfully restored after the recommended six-year monitoring period.

  • 89 of the 90 restored reefs (345/348 acres) met the minimum threshold oyster density and biomass metric when monitored at age six years. Seventy reefs met the target oyster density metric and 69 reefs met the target biomass metric at six years.
  • 88 of the 90 reefs (346/348 acres) met the shell budget metric when monitored at age six years.
  • 90 of 90 reefs met the multiple year class metric when monitored at age six years.

Of all reefs that were monitored at six years of age for reef height and reef footprint through fall 2019, 100% met these success criteria. In 2020 and 2021, no data was collected on these metrics due to COVID-related restrictions. Given that none of the reefs monitored for these parameters Bay-wide have failed, and that site selection criteria for restored reefs is similar, it is likely that the remaining six-year-old reefs in Harris Creek also meet these parameters.

Oyster monitoring reports can be found here:

Harris Creek Restoration Reefs

Below is an interactive map with the restoration reefs in the Harris Creek sanctuary. The legend and layers are located in the upper right-hand corner. You can click on a reef to see more information. The information was last updated in March 2023. ​ 

Restoration sites are identified as ‘seed only’ restoration (hatchery-produced spat-on-shell added to existing remnant reefs) or ‘substrate + seed’ restoration (adding reef-building substrate to the reef footprint, followed by planting with hatchery-produced spat-on-shell) or ‘premet’ (sites that already meet the Oyster Metrics target oyster density (50+ oysters per m2) and oyster biomass (50+ grams per m2) and did not receive initial restoration).