Get Full Government Meeting Transcripts, Videos, & Alerts Forever!
Get email alerts on the Open Space Mapping topic
No spam. Unsubscribe anytime.
Commission debates mapping methodology and data reliability for Davis open-space prioritization
Summary
The Open Space and Habitat Commission reviewed draft prioritization maps using 5-acre hexagons and multiple datasets, raised concerns about double-counting waterways and dated species records in CNDDB, and asked staff to produce a written explanation of data weights and a conserved-lands overlay before a September decision.
Michelle, the subcommittee lead on the parcel-identification project, presented the commission with newly acquired habitat and sensitive‑species datasets and a draft methodology for scoring 5‑acre hexagons across the Davis planning area. She said the city now has previously missing vector shapefiles and that the current scoring treats most attributes equally while acknowledging that weightings should be revisited.
"So basically last time we were missing three data sets... they sent out last week so got everything somehow," Michelle said, explaining the technical sources and that priority‑one habitat was scored as 1.0 and priority two as 0.5 under the draft scheme.
Commissioners questioned the approach to layering and weights. Several members pressed staff about a potential double count where county creek buffers (150 meters) and city drainage channels (30 meters) overlap in the same corridor. One commissioner warned this could make a single waterway count twice in the composite score and urged consolidation or reclassification into a single authoritative layer.
"We captured double count is the point," one commissioner said during the discussion, asking that the maps be simplified or merged so that creeks and urban drainage channels are not both counted at different buffer distances.
The commission also scrutinized the California Natural Diversity Database (CNDDB) occurrences that appear as large circles on the maps. Members noted these circles often represent historical observations that can be large and imprecise, and that some records date back decades. "It's very reliable... but there's a lot of false positives," a commissioner said, urging staff to remove records marked 'extirpated' and to cross‑check older observations against recent local surveys where possible.
Tracy, acting as staff liaison, said the city bought an annual subscription to the CNDDB for local planning use and explained the administrative steps: "I bought two years. So second renewal is 400." Commissioners requested a short written report documenting data sources, how each layer was scored (including the 12 attributes and eight categories), and the rationale for any buffer distances and weightings.
The commission asked staff to prepare three changes before the next substantive review: (1) provide a legend and short report explaining weights and methodology; (2) produce a conserved/easement overlay that distinguishes parcels already protected from those still available; and (3) reconcile creek/ditch layers to avoid double‑counting. Staff indicated a draft could be shared with the General Plan committee in July and finalized for commission consideration in September.
Next steps: staff will refine maps, add the requested overlays and documentation, and return with clearer legends and revised weightings for further discussion. The commission did not take a formal policy vote on the mapping method during this meeting.
