CDBG 2020

[damonmcc]

primary outputs:

• csvs with details about the CDBG eligibility of 2020 census block groups, tracts, and boroughs
• an excel file with three sheets to align with May 2019 output: Tract, Borough Block Group

source data:

• 2020 census tracts
• PLUTO 24v4
• 2020 HUD Low and Moderate Income Summary Data (LMISD)

source data we seem to be missing, but would only need for documentation:

• ACS data for total population in each census tract
• latest "Low and Moderate 4-Person Family Income Limit: $xx,xxx"

details from GDE Manual

NYC receives Community Development Block Grants from the U.S. Department of Housing and Urban Development (HUD). These grants may be used for projects in residential areas where over half the population is living in low- and moderate-income households.

A census tract is considered residential if at least 50.0% of the total built floor area is residential. This is determined by summing ResArea and BldgArea for MapPLUTO lots in the census tract. If at least 90% of a lot's area is in the tract, the entire lot is assigned to that tract. Otherwise, the building area is assigned proportionately based on the percent of the lot's area in each census tract.

The clipped version of MapPLUTO was used because otherwise waterfront properties on the East River in Queens and Brooklyn had a portion of their building area assigned to Manhattan. An additional check was added to verify that a lot's area was fully captured. This was a problem for waterfront lots that extended outside the tract boundaries.

new/active stuff

new source data in sharepoint

CDBG Eligibility by Census Tract: metadata, DCP website, Bytes, Open Data csv, Open Data fgdb

Status of Update

• source data extracted
• draft build succeeded
• draft build passed QA
• data packaged and distributed

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dev todos

• use >= in eligibility logic
• use HUD's LOWMOD_PCT for block groups and and 'LOWMOD/LOWMODUNIV` for tracts (instead of any total population data)
• remove artifacts of trying to use total population to determine eligibility
• create a README

dev questions

• should the eligibility logic be >= 50% and >=51%?
  • the language in the docs is "at least 50% of the total built floor area is residential" and "at least 51.00% of the residents are low- and moderate-income persons", but the excel sheet used >
  • answer from AD: use >=
• should we use HUD's "persons with the potential for being low/mod income" or total population to calculate eligibility?
  • answer from OMB: use HUD's "persons with the potential for being low/mod income" and update documentation
• there are 95 lots that are not entirely contained by city census blocks/tracts, so some bldg area is "lost" from pluto. Is this fine? Do we want to allocate 100% in these odd edge cases? See CDBG 2020 #1348 (comment)
  • DE idea: allocate the % of the lot that is in the city geographies because that's consistent with how they're allocated across multiple geographies and it isn't invalid that lots cross county lines

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old stuff (but both are related to geocoding CDBG projects, not determining census tract eligibility)

db-cdbg repo

DE CDBG sharepoint folder

[damonmcc]

will add this (new) data product to the DE repo as a dbt project

asked OMB some clarifying questions about the source data but we can proceed as-is

[damonmcc]

added a new DB to ed-data called db-cdbg per our wiki

[damonmcc]

added HUD LMISD source data sent by OMB to edm-recipes/inbox in S3

[damonmcc]

the build on the dev branch looked good. after archiving the latest dcp_mappluto_clipped, ran a build here and shared with @AmandaDoyle via email

[damonmcc]

per HUD LMISD data dictionary:

Field	Definition
LOWMOD	The count of Low- and Moderate-income persons.
LOWMODUNIV	Persons with the potential for being deemed Low-, Moderate- and Middle-income. Use as the denominator for LOW, LOWMOD, and LMMI %'s.
LOWMOD_PCT	The percentage of Low- and Moderate-income persons. Calculated from LOWMOD divided by LOWMODUNIV.

since, per the DCP website, a tract is eligible if "at least 51.00% of the residents are low- and moderate-income persons", seems like we need the total population of each 2020 tract and 2020 block group

@fvankrieken found a source dataset we already archive that may have this (I think dcp_pop_acs?

[fvankrieken]

dcp_censusdata (and dcp_censusdata_blocks) - just a lot smaller than the acs datasets

[damonmcc]

noting that some lots seem to extend outside of NYC. so <100% of their floor areas are assigned to their NYC census tracts/block groups

[fvankrieken]

lots not fully in NYC census geographies issue example

lot over osm basemap

lot in zola

area of interest in pff (where we can see cb boundaries

[damonmcc]

shared latest build from branch dm-cdbg-zeros with @AmandaDoyle for review

edit: noticed that, in the output shared, the borough-level % of population that is low/mod income was still using total population as the denominator

[damonmcc]

we've been asked to determine ZAP project eligibility using this new tract eligibility data. @AmandaDoyle wants an output to review by the morning of 1/8 (tomorrow)

will create a sub-issue for this

[damonmcc]

shared outputs for review on 1/8