How to Map Open Space for Community Rating System Credit

The GIS workflow gives details on how to access your community’s flood insurance rate maps and calculate the SFHA using GIS. See Activity 410 (page 410-1) in the CRS Coordinator’s Manual for detailed guidance.

See Figure 2 in the GIS workflow for an example of an SFHA map.

The SFHA area should be adjusted for three types of areas:

Open waters
Subtract open waters, such as lakes, bays, and large rivers, larger than 10 acres or for reaches of a river that are wider on average than 500 feet from bank-to-bank.

Federally owned or restricted lands
Subtract lands larger than 10 acres that are either owned by the federal government (e.g., military installations or national parks) or where the federal government prohibits development. Certain federal lands leased by private owners may not need to be excluded.

Other areas the community does not regulate
The community may opt to include or exclude nonfederal areas it does not have authority to regulate, such as state lands, tribal lands, or lands owned by another community. However, if these areas are included for open space credit, they must also be included for all CRS activities.

Open space credit can be earned in areas outside the SFHA that are subject to higher regulatory standards. These generally include areas in the “500-year floodplain” or other areas that the community has determined to be at risk. The total area of the SFHA plus the acreage where the community enforces development regulations similar to those enforced in the SFHA is called the “regulatory floodplain.” The community must map the area on its impact adjustment map and document its floodplain management regulations, per CRS Activity 410 (floodplain mapping). Communities should use this base map as they identify lands that may qualify for open space preservation credit.

Identify parcels that fall entirely or partially within the flood hazard areas—the SFHA, regulatory floodplain, and, if mapped, the coastal erosion or special flood-related hazard areas (e.g. tsunamis). See the GIS workflow for more details on how to do this.

See Figure 4 in the GIS workflow for an example of the resulting map.

Types of public land
State and local parks and easements intended to be kept in open space (as documented by the owning agency). Examples include state, county, and city parks and forest preserves, publicly owned beaches or natural areas, school playing fields, and floodplain easements dedicated to the community by developers. Federal lands do not qualify for credit.

Types of private land
Private wildlife or nature preserves that are maintained for open space purposes (as documented by the owner). Examples include church retreats, hunting club lands, and golf courses, nature preserves, and camping areas owned by nonprofit associations.

To determine which lands may qualify, consider the following:

The regulations or use restrictions must prohibit construction of new buildings, as well as filling, grading, or other activities that obstruct flood flows or remove flood storage in areas subject to riverine flooding. It is permissible to maintain existing levees and engineered dune and beach nourishment programs within the area.

If an ordinance prohibits residential development in the V Zone, floodway, or other portion of the floodplain, the community may request open space preservation credit for only those areas of the floodplain that are zoned for residential use.

The area where the regulations are in effect must be mapped or defined by lots or a legal description so it can be mapped. For example, credit will not be given for a wetlands regulation that depends on site analysis to define whether a property is a wetland.

Credit is only given for regulated lands that are undeveloped at the time of application for CRS credit.

See the GIS Workflow for more details on how to map these areas and exclude lands that are not vacant.

Because federal lands (such as military bases and national parks, forests, or refuges) and open water (such as rivers, lakes, and bays) do not qualify for credit, these areas need to be excluded from consideration at the parcel level. The results of the analysis in Step 1.b. can be used for this purpose.

To be considered as “open space,” parcels must have no buildings, storage, filling, significant pavement, or other encroachments to flood flows. Parcels of 10 acres or less in size that contain insurable buildings cannot be included in open space credit calculations, with some exceptions (see CRS Coordinator’s Manual for details). “Non-insurable” structures such as open pavilions or bleachers (as defined in Section 301 of the CRS Coordinator’s Manual) do not disqualify a parcel. Parcels greater than 10 acres in size that contain an insurable building may still qualify for open space credit if the building is essential to the use of that parcel as open space (e.g. restroom facility).

Parcels with fill, storage of materials, or other encroachments would be considered to aggravate flooding on other properties, for example, if they create obstructions to the flow or loss of storage of floodwaters, and would need to be excluded. Note: this does not apply to construction of sand dunes, beach nourishment, and habitat restoration projects. See CRS Coordinator’s Manual Guidance for Activity 420 for details.

If a parcel is intended for a long-term use that is not eligible for open space preservation credit, the parcel does not qualify for such credit even though it may currently be in a natural state or open space. Zoning or land-use classification for the parcel can help determine whether the property is intended for uses other than open space. The GIS workflow can help with this step.

Impervious surfaces
Areas considered to have large amounts of impervious surfaces—such as driveways, parking lots, buildings, or other permanent structures, or paved amenities (such as ball courts)—will need to be excluded from calculations. Minor areas such as sidewalks, trails, or pervious pavements, as well as grassy athletic fields, would not need to be excluded.

Linear features and rights-of-way
Use GIS to identify and exclude features considered necessary to serve the development or use of an area. These include linear features such as streets, pavement, parkways, railroads, levees, canals, ditches, and channels, as well as rights-of way such as utility easements.

The GIS workflow provides for more details on how to exclude these areas. See Figure 5 in the GIS workflow for a map that shows eligible and excluded areas within an open space parcel.

Calculate the portion of each property that falls within the adjusted SFHA (or regulatory floodplain, if applicable) in acres. From that area, subtract the acreage for any non-qualifying areas within the floodplain, such as the portion of the property covered with impervious surfaces or ineligible land uses. See page 420-4 of the CRS Coordinator’s Manual for a list of non-qualifying areas. See Table 1 for an example. The GIS workflow provides details on how to do this task using GIS.

To determine the total credit for preserved open space, add up the total acreage for all parcels that qualify as preserved open space as calculated in sub-step “a.” This total will serve as the “numerator” for calculating potential credit. The Worksheet to Calculate Open Space Credit can help perform these calculations.

Credit for preserved open space is calculated using the ratio of preserved open space in the regulatory floodplain to the total area of the SFHA (the “impact adjustment”). To calculate the impact adjustment ratio, divide the result from sub-step “b” (the total acreage of preserved open space in the floodplain) by the total acreage of the community’s SFHA. Then, multiply the resulting ratio by the maximum number of points for the category (1,450) to determine total credit that could be earned for these preserved open space parcels. Note: All points must be verified by FEMA before they are credited.

Example calculations:

Total SFHA area (aSFHA) = 848 acres

Creditable preserved open space in the regulatory floodplain (aOSP) = 126 acres

Ratio of creditable open space (rOSP) = aOSP/aSFHA = 126 acres/848 acres = 0.1486

Total OSP points = 1450 (max per category) * rOSP = 1450 * 0.1486 = 215

See Table 1 for an example. The Worksheet to Calculate Open Space Credit can help you with this task.

Section 422.b. (page 420-12) of the CRS Coordinator’s Manual guidance for Activity 420 describes criteria for qualifying deed restrictions (DR). Generally, they must prohibit new buildings, run with the land (e.g., transfer to future owners), and be amended only by a court for just cause. These can include public lands acquired with state or federal funding that require a deed restriction as a condition of funding, including lands purchased through FEMA mitigation grant programs or other restrictions placed on a property by an owner, agency, or organization. For any qualifying parcels, calculate the additional credit for each parcel using the method below or using the Worksheet to Calculate Open Space Credit (up to 50 points).

Calculation—for each parcel:

If the area within the regulatory floodplain protected by deed restriction is the same as the area that qualifies as preserved open space (OSP), use the same “impact adjustment” ratio as calculated for open space preservation credit in Step 4.c.

If the area within the regulatory floodplain protected by deed restriction differs from the area that qualifies as preserved open space, calculate the area protected by the deed restriction and recalculate the ratio of the deed-restricted parcel acreage to the total acreage of the community’s SFHA.

Multiply the parcel’s “impact adjustment” ratio by the maximum of 50 points for this category.

Tips! See ASFPM’s CRS “Green Guide” Profile for Element 422.b.

Parcels that qualify for open space preservation (OSP) credit may receive additional credit if they are preserved in or restored to a natural state. If so, they may also qualify for even more credit if they are included in a natural floodplain functions plan, designated as critical habitat for threatened or endangered species, or in a designated open space corridor. Section 422.c. (page 420-14) of the CRS Coordinator’s Manual provides detailed guidance for each category. For each qualifying parcel, calculate the additional open space credit using the same method as for “Deed Restrictions” above or using the Worksheet to Calculate Open Space Credit (up to 350 points).

NFOS1 = open space parcels preserved in their undeveloped natural state (have not been built upon, graded, or farmed), or that were formerly farmed or developed but have been restored to their natural state (pre-development conditions). Note: this is a pre-requisite to receive credit for the other three types of natural functions open space (up to 190 points).

NFOS2 = parcels that qualify as NFOS1 and are designated in a natural floodplain functions protection plan that meets the criteria for such plans as described in Element 512.c. (pg. 510-35) of the CRS Coordinator’s Manual (floodplain management planning). Such plans can include a plan credited under Activity 512.c, a habitat conservation plan, habitat protection or restoration plan, “green infrastructure plan,” comprehensive plan, or other community plan that recommends actions to protect the ecological attributes of the watershed or floodplain (up to 50 points).

NFOS3 = parcels that qualify as NFOS1 and are designated as critical habitat for threatened or endangered species, or have these species present. This includes species on an official federal or state list as threatened or endangered or as a “species of concern.” For federally listed species, use the U.S. Fish and Wildlife Service’s iPAC website to see what species might be present on each parcel, or see maps showing critical habitat for marine species under NOAA’s jurisdiction. Or consult with your state’s wildlife or natural resource agency (up to 50 points).

NFOS4 = parcels that qualify as NFOS1 and are in an open space corridor or connected network (e.g., of wetlands, woodlands, or wildlife habitats) designated in an approved plan (up to 60 points). Tip! State CELCP plans or state wildlife action plans may be good sources for this information.

Tips! See ASFPM’s CRS “Green Guide” Profile for Elements 422.c. and 512.c.

The CRS offers credit for preserved open space within areas subject to the following flood-related hazards: uncertain flow paths (alluvial fans and channel migration), closed basin lakes, ice jams, land subsidence, mudflows, and tsunamis (up to 150 points). To qualify, the community needs to have mapped its special flood-related hazard areas (see Element 412.f. on page 410-24) and the area must be subject to special hazard-specific regulations credited under Activity 430, Higher Regulatory Standards (see 432.k.-m. on pages 430-32-48). See Element 422.d. on page 420-19 of the CRS Coordinator’s Manual for detailed guidance.

To determine the amount of SHOS credit:

Calculate the area of the special hazard-prone open space. Note: this area may extend outside the SFHA.

Multiply that area by 150, and then divide the result by the size of the community’s adjusted SFHA (from Step 1).

Tips! See ASFPM’s CRS “Green Guide” Profile for Elements 422.d. and 432.l.

The CRS offers bonus credit for preserved open space within a community’s mapped coastal erosion hazard areas that are landward of a coastline eroding at a rate greater than or equal to 1.5 feet per year (up to 750 points). To qualify, the community needs to have mapped its coastal erosion hazard areas (Element 412.f, page 410-24 of the CRS Coordinator’s Manual), kept the maps updated (Element 442.d, page 440-13), and received credit under Element 432.n. (page 430-48) for its coastal erosion regulations.

To determine the amount of CEOS credit,

Calculate the size of the community’s coastal erosion hazard areas mapped under Element 412.f (page 410-24) and the area that qualifies for CEOS.

Calculate the total length of the community’s coastline and the length of coastline that is eroding at ≥ 1.5 feet per year.

If the erosion projections consider future sea levels, determine the year to which the location of the erosion reference feature is projected and select the applicable multiplier for consideration of future sea level rise (1.2 for using NOAA’s “intermediate-high” projection for the year 2100 and 1.5 for using the NOAA “high” projection for 2100). See Element 404 (page 400-14) of the CRS Coordinator’s Manual for guidance on sea level rise projections).

Calculate credit using the formula for Element 422.e. on page 420-20 of the CRS Coordinator’s Manual or using the “Worksheet to Calculate Open Space Credit”.

Tips! See ASFPM’s CRS “Green Guide” Profile for Elements 422.e, 432.n, and 442.d

To determine the total extra credit, sum the credit earned for all parcels or areas within the categories above: deed restrictions, natural functions open space, coastal erosion open space, and special flood-related hazards open space. The “Worksheet to Calculate Open Space Credit,” below, can help you with this task.

This “impact adjustment map” should clearly identify the portion of each creditable open space property within the regulatory floodplain and identify any areas excluded from the calculations. The map should also identify which parcels qualify for extra credit based on deed restrictions (mark as DR), natural functions (mark as NFOS#), or special flood-related hazard areas (mark as SHOS and/or CEOS). This map may be generated using any convenient base map or in a GIS. See Section 403 (page 400-8) of the CRS Coordinator’s Manual for guidance on selecting a base map.

See Figure 8 in the GIS workflow for an example of an impact adjustment map.

Provide a list of parcels that qualify for open space preservation credit (OSP). The list must correspond to the impact adjustment map. For each parcel, include parcel owner, land use designation, total acreage of parcel, and acreage of parcel within the SFHA, and whether the parcel qualifies for any “extra credit” (DR, NFOS, CEOS, or SHOS). If the parcel falls within a regulated area outside the SFHA, also include the parcel’s flood zone. The completed Worksheet to Calculate Open Space Credit (Excel spreadsheet) can be used as this documentation.

See Sections 231.b and c. (page 230-4) of the CRS Coordinator’s Manual for guidance on documenting regulatory language. Digital documentation is preferred.

For each parcel that is preserved through ownership as public land or private wildlife or nature preserves and maintained for open space purposes (per Section 422.a., credit criterion 3a or b, page 420-6), provide documentation that the owner will keep the parcel open. See Template: Letter/Documentation from Property Owner

For each parcel preserved through regulation, provide a copy of the ordinance language that prohibits structures and fill in all or part of the regulatory floodplain. See also Sections 231.b and c. (page 230-4) of the CRS Coordinator’s Manual on documenting regulatory language.

Credit for deed restrictions must be documented with a copy of the actual deed restriction.

The documents can be

For NFOS1, a report or plan prepared by a qualified agency, such as a habitat conservation plan, a natural areas inventory, green infrastructure plan, etc., that includes the property to be credited. Tip! For many coastal states, the state’s CELCP plan is a good place to find a list of such plans in the coastal area.

A memo or letter signed by a professional in a natural science such as botany, biology, forestry, or landscape architecture. See sample natural floodplain functions form.

For NFOS2 (lands designated in a natural floodplain functions protection plan), provide a copy of the plan and the resolution or other formal adoption action. This is not needed if the plan is submitted for credit under CRS Activity 510.

For NFOS3, provide documentation if any threatened or endangered species are present and documentation from a federal or state wildlife agency that the species is listed.

For NFOS4, provide the appropriate open space corridor plan.

Provide a map of, or include on the impact adjustment map, the special flood-related hazard area and its relationship to the open space parcel. Also, provide a copy of special hazards regulations that would apply to the area if it were not open space.

Provide a map of, or include on the impact adjustment map, the coastal erosion hazard area and the portion of the open space parcel that falls within that area. Note: To receive this credit, the community also needs to receive at least 25 points for mapping coastal erosion areas under Activity 412.f, 20 points for regulating new development in coastal erosion areas under Activity 432.n, and 10 points for keeping maps updated under Activity 442.d.

Identify parcels that fall within the SFHA or, if applicable, the regulatory floodplain with high amounts of open land and a low amount of impervious surface using land cover data (e.g., create an “open space” layer from forest, wetlands, grassland classes). Exclude parcels that do not qualify (see Step 3) and those that have already received CRS credit for open space preservation (Activity 420). Then, calculate the portion of each parcel that falls within the SFHA. Additional criteria may be considered for screening as well, such as type of ownership, tax value, or repetitive loss areas.

Conduct an initial screening to determine the parcel’s potential to earn open space credit. Using the method in Step 4, determine how much of the parcel would qualify as preserved open space if protected, for example, after excluding impervious surfaces or other non-qualifying uses. Then determine whether the parcel could qualify for additional credit for natural functions or special flood-hazards open space (see Step 5). The CRS Parcel Screening and Documentation Checklist can help with this task.

Work with land trusts, open space committees, or nonprofit organizations to determine whether the identified parcels support their planning efforts. If so, work with them to consider protecting parcels through these voluntary approaches: purchase or transfer of development rights, acquisition of the land, conservation easement, or other deed restriction on the land. Some landowners may be willing to consider donation of an open space easement to a qualified conservation organization or buyout of a property that has experienced repetitive losses.

Open Space Incentives: A community can receive credit for using such open space incentives as density transfers, transfer of development rights, cluster developments, planned unit developments, setback rules (such as buffers for shorelines or wetlands), and others. See Element 422.f. on page 420-21 of the CRS Coordinator’s Manual for more information.

Low-Density Zoning: A community can receive credit for zoning designations that keep the floodplain substantially open, such as zoning for agricultural uses, conservation, or low-density residential use (5-acre lots or larger). See Element 422.g. on page 420-28 of the CRS Coordinator’s Manual for more information.

Natural Shoreline Protection: A community can receive credit for having programs in place to protect channels and shorelines in their natural state. See Element 422.h. on page 420-30 of the CRS Coordinator’s Manual for more information.

Special Flood Hazard Areas: Communities can earn credit for open space preservation and low-density zoning in areas subject to special inland and coastal flood hazards. Inland flood hazards can include uncertain flow-paths (alluvial fans and channel migration, closed basin lakes, ice jams, land subsidence, and mudflows. Special coastal flood hazards include tsunamis as well as coastal erosion. See Element 422.d. on page 420-19 of the CRS Coordinator’s Manual for more information.