4.11 Wetlands

Goal 11 - Wetlands

Preserve, create and restore wetland resources and maximize the benefits and functionality of wetlands to the watershed.

Discussion

The Functional Assessment of Wetlands evaluated 485.8 acres of wetlands in the Gleason Lake Creek subwatershed, of which 121.6 acres were in the Preserve classification (see Table 8 in Section 2.5.4 and Figure 12).  There are several wetlands of exceptional and high quality functions and values within this subwatershed.  Their conservation is integral to achieving ecological integrity goals, as well as water quality, stormwater management, and floodplain management goals.

A key strategy of this plan is regulation of wetland impacts in accordance with a management classification based on the functions and values findings of the Functional Assessment of Wetlands.  Wetlands are assigned to a classification – either Preserve or Manage 1, 2, or 3 – and allowable impacts would be based on that classification.  The wetlands with the highest values – those in the Preserve classification – would be allowed minimal impacts.  The Manage classifications would be allowed some impacts, such as accepting new stormwater discharges, depending on classification.   This strategy would preserve existing high values such as habitat, vegetative diversity, and sensitivity, while also recognizing that wetlands play an important part in managing stormwater.  Wetlands provide essential storm and flood water storage.

Wetlands of exceptional or high vegetative diversity or fish or wildlife habitat value have been designated key conservation areas (see Figure 19), as have wetlands that are riparian to streams or channels, have high restoration potential, or that provide key floodplain storage.  Except for those in the Preserve classification, which would be managed to an even higher standard, these conservation wetlands would be managed as if they were Manage 1 classification wetlands, with limitations on the amount of new runoff that can be directed to them, and a requirement to pretreat any new discharges to them.

An important part of achieving the goal of no net loss of wetland size, quality, and type will be tracking wetland impacts to assist in identifying future restoration or wetland creation needs.

Equally important to the regulation of wetlands is the restoration of degraded wetlands within the subwatershed.  Figure 14 identifies wetlands based on restoration potential.  Only a few small wetlands were identified in the FAW as having moderate to high restoration potential.  Restoring wetlands increases specific functions and values of the resource within the watershed ranging from management of flows to water quality improvement to enhancement of the overall ecosystem, particularly within identified corridors.

Desired Outcomes:  Maintain existing quantity and quality of wetlands throughout subwatershed; improve wetland and surface water quality within Key Conservation Areas.

Metrics:

  • Wetland quantity (acres)
  • Wetland quality (acres/management classification)
  • Acres of restored/created wetland within Key Conservation Areas

Goal 11.1 - Gleason Lake

Maintain existing acreage of wetlands in the subwatershed and achieve no net loss in their size, quality, type, and biological diversity.

Actions

  1. Regulate wetland impacts commensurate with the quality of the wetland as determined by the Management Classifications identified in the Functional Assessment of Wetlands (FAW).
  2. In consultation with LGUs through an appropriate rulemaking process, amend existing or establish new District rules requiring submittal of a functions and values assessment for all proposed wetland impacts requiring a permit; mitigation of all fill in Preserve category wetlands; and specifying by management classification stormwater discharge pretreatment, buffer, hydroperiod, and other wetland standards.
  3. Require that wetland losses be mitigated within the lake subwatershed in which they occur, either Gleason or Hadley Lake subwatershed.
  4. Track wetland losses resulting from permitted fill.
  5. Restore degraded wetlands in Key Conservation Areas to improve vegetative diversity and ecological integrity, with priority given to wetlands where restoration could improve management classification to at least a Manage 1.  Restore other wetlands as opportunities arise.
  6. Restore vegetative diversity and ecological integrity of all wetlands in which the District acquires an interest.
  7. Update the MCWD Functional Assessment of Wetlands to maintain a current inventory of wetland location and size, as well as function and value.

Goal 11.2 - Gleason Lake

Increase the quantity, quality, and biological diversity of Gleason Lake subwatershed wetlands through the restoration of impacted wetlands or creation of new wetlands.

Actions

  1. Restore other hydrologically impacted wetlands in Key Conservation Areas determined in the FAW to be “restorable,” where restoration could improve vegetative diversity and ecological integrity.