6 Things to Look Out For in Your LAM Data

If you’re working at an urban water supply agency in California, then you’ve probably recently received your landscape area measurement data from DWR, and you may be wondering what to do now!

To help the water community better understand what to look for in the LAM data, the CaDC has identified six key areas to assess when evaluating the quality of the data provided to your agency. These recommendations come from our own experience helping agencies to assess their data and estimate their residential objectives, as well as from the excellent advice of ACWA and the San Diego County Water Authority.

Land Use Assumptions

When starting to evaluate your LAM Data, be sure to check for mislabelling of voided or non-residential areas in your water service area. Sometimes the land use code for a parcel is just missing, while in other cases a parcel might be labeled as VACANT when in fact there is a home there. If these parcels are not counted as residential, then their landscape will not be included in your budget.

In the center, the highlighted parcel was classified as vacant land, but satellite imagery indicates that a house is present.

Multifamily Landscape Areas

Multifamily landscape areas present another source of potential confusion between self-reported calculations and State assessments because of the variety of categories that can be applied to them (i.e. residential, commercial, or dedicated landscape). When reviewing your LAM data, check to ensure that these areas are classified as residential (or are otherwise consistent with the State’s guidance). This is more often an issue with condos than with apartments, in which each condo has its own parcel, but common areas fall within a separate parcel.

Condos for which landscaping is not counted as residential.

Apartments where landscaping is counted as residential.

Mixed-Use Housing

Mixed-use housing — or areas in which both residential and non-residential water uses are present on the same parcel — can generate problems as well. For example, a building that serves as a home on its second floor but a storefront on its first could be classified as either a residential or commercial property. Water districts with a high proportion of mixed-use housing areas will need to pay special attention to the classifications in their LAM data in order to assure that their calculations are coherent with the State’s objective calculation.

In a rapid assessment of LAM data for one agency, we flagged this parcel of land for secondary review after noticing that, while this area had a residential meter, it was identified under the land-use code OFFICE BLDG (GENERAL).

Boundary Areas

In areas where land is shared, or in which the absence of a physical boundary makes it difficult to calculate individual water use, attention should be paid to the accuracy of the boundaries drawn in State and self-reported data. In particular, look out for cut-outs and non-contiguous areas in your LAM data to make sure that they accurately reflect the boundaries determined for your service area.

Residential meters (black dots) located outside the Area of Interest (AOI) representing the supplier’s service area boundary.

Parkways

Parkways, or areas between the sidewalk and the road that are irrigated by a residential customer, are taken into consideration in customer water demand calculations for certain highly-impacted agencies. Nevertheless, the State does NOT include parkways in their calculations of LAM data or final water demand objectives. Consequently, agencies should pay careful attention to these areas in their water demand calculations, making sure to remove them from the ultimate water demand calculation to avoid excess reporting of water use.

In this example, we see that the parcel area for each individual residence does NOT include the parkway beyond a resident’s official parcel. When evaluating your LAM data, be sure to exclude these areas from your water demand calculations to avoid excess water use estimates.

Easements

Finally, easements — areas outside a residential parcel but which are irrigated by individual residents — require specific considerations for both the DWR and individual water agencies. For example, consider an area in which a resident’s “yard” includes a strip of land not included within their parcel boundary. In these cases, residents may irrigate areas not included in their parcel because they lack a physical separation from the resident’s own land parcel. If these areas are common to your service area, they should be flagged and reported to the DWR to determine if this landscape needs to be included in your budget.

The most important principle to keep in mind when checking (and eventually reporting) this data is to make sure that water use in areas that DWR thinks are residential ends up being reported as residential while water use in areas that DWR does not think are residential ends up being reported elsewhere (or not at all).

Making sure that the state’s definitions ultimately align with the definitions you use when reporting is key. By including areas not previously added to the overall water demand budget and removing those that the State does not require for compliance, agencies can avoid the high costs associated with compliance shortfalls and fully benefit from their own existing conservation efforts to reduce water demand.

If you are interested in learning more about the CaDC’s approach or would like to receive a low-cost, rapid analysis to check your data quality and estimate your residential water use objective, please contact us at info@theCaDC.org.