performance standards and credit release schedules for

Performance Standards and Credit Release Schedules for Wetland Mitigation Sites

April 2019

Overview

• Reference Materials

• Performance Standards

• Vegetation

• Hydrology

• Credit Release Schedules

Reference Materials

• Performance Standards and Credit Release Schedules Guidance (BWSR and Corps 2015)

• Regulatory Guidance Letter 19-01

• Target Hydrology and Performance Standards for Compensatory Mitigation Sites (Corps 2019)

Performance Standards

Purpose

• Required as part of a complete Mitigation Plan (MP) under the Federal and State rules.

• Used to assess whether the project is achieving its objectives


Uses

• Provide a metric for assessing the need for corrective actions or management activities when site development is inconsistent with the MP.

• Used to justify the release of credits when site attributes reflect successful development towards site objectives in the MP.

Community Interim Performance Standards Monitoring Data

2016 2017 2018

Mesic Prairie Native vegetation having ≥ 50% total cover 40% 56% 73% > 75% total vegetative cover >75% 93% 100%

Wet Meadow -1 ≥ 5 native herbaceous species 13 26 14 Native herbaceous species total cover ≥ 50% 78% 81-96% 100% > 75% total vegetative cover 90-100% 90-100% 100%

Wet Meadow -2 ≥ 5 native herbaceous species 20 11 17 Native herbaceous species total cover ≥ 50% 48% 58% 81% > 75% total vegetative cover 90-100% 90-100% 93%

Shallow Marsh

< 85 % cattail 40-60% 54-60% 50-70% < 20% cover other non-natives < 5% < 5% < 5% ≥ 2 native aquatic plants 5 >12 >12 ≥ 20% total cover of native aquatic plants 25-50% 25-50% 25-50%


Development

• The 2015 Guidance has a section dedicated to developing performance standards (1.1) and identifying attributes to measure (1.2)

• The guidance affords flexibility to sponsors but it is important to remember that all PS have the following characteristics• Can be objectively measured using standard, repeatable methodology;• Can be expected to change within the typical monitoring period (5-10 years)• Can be practicably measured

• Almost every wetland bank site today is using vegetation and/or hydrology as the basis for assessing site performance.


Vegetation

• The agencies have established a set of typical measurements used for performance standards in Minnesota (2015 Guidance Section 1.3)

• Percent absolute cover of bare ground/open water• Percent relative cover of native, non-invasive

species• Percent relative cover by hydrophytes (wetland

plant communities)• Plant species richness


Vegetation- Percent absolute cover of bare ground/open water

• Interim standard is typically 20% and final is 10% for non-inundated communities and upland buffer

• For inundated communities, the final standards are higher

• As an alternative, some banks are using unvegetatedarea as a measure of performance scaled to show decreasing size as the site develops


Vegetation- Percent absolute cover of bare ground/open water

Wright County Site

Milestone Wet Meadow Shallow Marsh Deep Marsh Upland Prairie

Vegetation Interim 1 25% 70% none 20%

Vegetation Interim 2 15% 60% none 10%

Vegetation Final PS 10% 40% none 5%

McLeod County SiteMilestone Wet Meadow Shallow/Deep Marsh Upland PrairieVegetation Interim 1 40% 40% 35%Vegetation Interim 2 30% 40% 25%Vegetation Final PS 10% 30% 20%

Nicollet SiteMilestone Wet Meadow Upland PrairieVegetation Interim 1 no unveg areas greater than 400sf no unveg areas greater than 400sfVegetation Interim 2 no unveg areas greater than 100sf no unveg areas greater than 100sfVegetation Final PS no unveg areas greater than 10sf no unveg areas greater than 10sf


Vegetation - Percent relative cover of native, non-invasive species

• The minimum amount for most wetland plant community types is greater than 50% (dominance) with increasing relative cover as the site develops

• The standard for the final release has typically been greater than or equal to 80% but in the northeast has been 90% or higher



• Because of the challenges associated with establishing vegetation in marsh communities and managing non-native cattail, an initial standard less than 50% has been approved (but typically not less than 40%)

• The standard for the final release in these communities is also reduced with 70% being most commonly used

• For upland buffer (prairie) an interim 1 between 50% and 60% and a final between 80% and 90% is typical



Wright County Site

Milestone Wet Meadow Shallow Marsh Deep Marsh Upland Prairie

Vegetation Interim 1 50% 40% 40% 60%

Vegetation Interim 2 70% 50% 50% 75%

Vegetation Final PS 80% 70% 70% 90%

McLeod County SiteMilestone Wet Meadow Shallow/Deep Marsh Upland PrairieVegetation Interim 1 50% 40% 50%Vegetation Interim 2 65% 55% 65%Vegetation Final PS 80% 70% 80%

Nicollet County SiteMilestone Wet Meadow Upland PrairieVegetation Interim 1 50% 50%Vegetation Interim 2 60% 70%Vegetation Final PS 80% 90%


Vegetation - Percent relative cover by hydrophytes (wetland plant communities)

• The minimum amount is greater than 50% relative cover

• The wetter the water regime of the wetland the greater the % for this standard

• Example: Seasonally flooded basin could be 50% throughout while final for shallow marsh could be 90%

• Variations across wetland plant community type are expected but percent cover should increase during monitoring period


Vegetation - Plant species richness

• This standard has the most variation between wetland plant community types, however, the ranges are very similar between banks

• Standards should show an increase in species richness during the monitoring period

• Upland prairie/wet meadow: Interim 1 is typically 5 species with a final of 20 species

• Marshes: Interim 1 is typically 3-5 species, with final of 5 *



• Do: Incorporate NNI and relative cover into proposed standards (i.e., #NNI, each with at least x% cover)

• Don’t: Incorporate dominance into proposed standards (ie., # species, with # being dominants)



Wright County SiteMilestone Wet Meadow Shallow Marsh Deep Marsh Upland PrairieVegetation Interim 1 4 3 2 5Vegetation Interim 2 10 4 3 10Vegetation Final PS 12 5 3 15

McLeod County SiteMilestone Wet Meadow Shallow/Deep Marsh Upland PrairieVegetation Interim 1 5 3 6Vegetation Interim 2 8 5 8Vegetation Final PS 10 5 10

Nicollet County SiteMilestone Wet Meadow Upland PrairieVegetation Interim 1 5 NNI, 2 dominant NNI 6 NNI, 2 dominantVegetation Interim 2 10NNI, 3 dominant NNI 10NNI, 3 dominantVegetation Final PS 20NNI, 4 dominant NNI 20NNI, 4 dominant NNI


Vegetation

• Thresholds for the same communities should be similar for banks in the same region

• Thresholds could vary between communities

• This presentation gives some general concepts and ranges, but some sites warrant different standards

• Thresholds proposed that are outside the norm should be accompanied by a rationale


Hydrology

• In March 2019 the Corps released the availability of Target Hydrology and Performance Standards for Compensatory Mitigation Sites Version 6.0

Credit Release Schedules

• Required by both the state and federal programs

• Outlines the milestones, amounts, and types of credits to be released through the establishment period.

• At the end of the MP phase the agencies will provide an approved credit release schedule (CRS) based on the information in the MP.


• 2015 Guidance contains an example credit release schedule that can be used for a mitigation project

• The table is only an example and sponsors have the flexibility to propose other release amounts provided there is good reason to do so


As a means of providing some additional guidance on the development of credit release schedules the agencies have agreed to the following:

• the initial release can be no more than 15% of the total projected credits (WCA rule)

• the hydrology credit release can account for up to 45% of the total projected credits

• the final release should be no less than 20% of the total projected credits


As a means of providing some additional guidance on the development of credit release schedules the agencies support the following:

• the hydrology standards must be met for two years but they do not have to be consecutive years

• More than one vegetation credit release can occur if the site has developed more rapidly than anticipated and both interim standards are met

• Credits from buffer could be released at the same time credits from other AECs are released


Alternative Credit Release Schedule (Assuming Both Vegetation and Hydrology Are Restored)

Wetland Credit TypeFinal

Projected Credits

Initial Hydrology Vegetation 1 Vegetation 2 Final

15% 45% 10% 10% 20%

Fresh (wet) Meadow A A(0.15) A(0.45) A(0.10) A(0.10) A(0.20)

Shallow Marsh B B(0.15) B(0.45) B(0.10) B(0.10) B(0.20)

Questions

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