As we try to adapt to climate change, understanding how our changing hydrology funnels through legal filters will be crucial.

That’s why the South Central Climate Adaptation Science Center funded this terrific piece of work by UNM Water Resources Program student Annalise Porter: New Mexico’s Greenbelt Law: Disincentivizing Water Conservation Through Agricultural Tax Breaks, just out in the Natural Resources Journal, a law journal.

Annalise studied the history of New Mexico’s greenbelt law, which provides substantial tax breaks for land deemed “agricultural”. The intent of the 1967 law, as the New Mexico Supreme Court noted in a 1980 decision, was the protection of subsistence farming against the impacts of rising property values and therefore rising taxes:

It is clear that the legislative intent behind this special method of property tax valuation is to aid the small subsistence farmers in our state.

In practice, today in the greater Albuquerque metro area the law enables vast swaths of lovely green space around affluent people’s homes across Albuquerque’s valley floor. Annalise estimated some 11,000 acre feet per year of consumptive use on parcels irrigated under the agricultural tax exemption.

To be clear, not all of the land and water is supporting green space for the affluent. There’s land in Annalise’s inventory that clearly looks like traditional farming. But a huge fraction of the land is located in Albuquerque’s most affluent – and greenest – valley communities, places that are home to very little commercial or subsistence farming.

To also be clear, green space is of significant non-market value! But as climate change reduces our available water supply, our continuing insistence on funneling climate-changed hydrology through antiquated laws, and our continued resistance to changing them, bears scrutiny.

Co-authors are Bob Berrens, UNM Economics and former Water Resources Program director, and myself. Annalise did all the actual hard work!