One of four large valleys on the windward side of East Moloka'i, H & amacr;lawa was a major centre of traditional irrigated taro cultivation in the 19th and early 20th centuries. Leveraging prior results of archaeological research undertaken in 1969-1970, from 2020 to 2022 we investigated the valley's irrigated and dryland agricultural features in order to better understand the longue dur & eacute;e of agricultural development, and to assess the long-term sustainability of the agroecosystem. Extensive sampling and analysis of soil nutrient properties reveal that the colluvial slopes have the greatest potential to support intensive cultivation, and that the irrigated alluvial flats are likely enriched by periodic transport of colluvial sediments due to flooding and overland mass transport. The earliest evidence for agricultural activities, dated to ca. AD 1200, is suggestive of shifting cultivation on the colluvial slopes. Stone-faced irrigated terraces were in place by at least by the late 13th or early 14th centuries, and a stone-lined irrigation canal by the mid-15th century. Extensive pondfields on the lower alluvial flats near the river mouth were constructed later, in the mid-17th century, presumably after the marshy terrain was elevated through deposition of sediments eroded from the interior valley slopes. Extensive dryland (non-irrigated) terraces were constructed on the colluvial slopes in the 17th and 18th centuries. Geochemical analysis of stratified sediments in pondfield terraces is indicative of some nutrient draw-down through intensive cultivation over long time periods, however the agroecosystem remained sustainable due to continued rejuvenation of soil nutrients through regular down-valley transport of fertile colluvium. Potential drivers of agricultural intensification are discussed. H & amacr;lawa, l'une des quatre grandes vall & eacute;es situ & eacute;es du c & ocirc;t & eacute; expos & eacute; au vent de Moloka'i Est, & eacute;tait un important centre de culture traditionnelle du taro irrigu & eacute; aux XIXe et d & eacute;but XXe si & egrave;cles. En nous appuyant sur les r & eacute;sultats de recherches arch & eacute;ologiques men & eacute;es en 1969-1970, nous avons men & eacute;, de 2020 & agrave; 2022, des & eacute;tudes et des fouilles dans les zones agricoles irrigu & eacute;es et s & egrave;ches de la vall & eacute;e afin de mieux comprendre le d & eacute;veloppement agricole & agrave; long terme et d'& eacute;valuer la durabilit & eacute; & agrave; long terme de l'agro & eacute;cosyst & egrave;me. Des & eacute;chantillonnages et analyses approfondis des propri & eacute;t & eacute;s nutritives du sol r & eacute;v & egrave;lent que les pentes colluviales pr & eacute;sentent le plus fort potentiel pour une culture intensive, et que les plaines alluviales irrigu & eacute;es sont probablement enrichies par le transport p & eacute;riodique de s & eacute;diments colluviaux d & ucirc; aux inondations et au transport terrestre de masse. Les premi & egrave;res traces d'activit & eacute;s agricoles, dat & eacute;es d'environ 1200 apr & egrave;s J.-C., sugg & egrave;rent une culture itin & eacute;rante sur les pentes colluviales. Des terrasses irrigu & eacute;es & agrave; parement pierreux & eacute;taient en place au moins & agrave; la fin du XIIIe ou au d & eacute;but du XIVe si & egrave;cle, et un canal d'irrigation bord & eacute; de pierres & eacute;tait en place au milieu du XVe si & egrave;cle. De vastes champs d'& eacute;tangs sur les plaines alluviales inf & eacute;rieures pr & egrave;s de l'embouchure du fleuve ont & eacute;t & eacute; am & eacute;nag & eacute;s plus tard, au milieu du XVIIe si & egrave;cle, vraisemblablement apr & egrave;s que le terrain mar & eacute;cageux ait & eacute;t & eacute; sur & eacute;lev & eacute; par le d & eacute;p & ocirc;t de s & eacute;diments & eacute;rod & eacute;s des pentes int & eacute;rieures de la vall & eacute;e. De vastes terrasses s & egrave;ches (non irrigu & eacute;es) ont & eacute;t & eacute; am & eacute;nag & eacute;es sur les pentes colluviales aux XVIIe et XVIIIe si & egrave;cles. L'analyse g & eacute;ochimique des s & eacute;diments stratifi & eacute;s des terrasses des champs d'& eacute;tangs indique une certaine absorption des nutriments par la culture intensive sur de longues p & eacute;riodes. Cependant, l'agro & eacute;cosyst & egrave;me est rest & eacute; durable gr & acirc;ce au renouvellement continu des nutriments du sol par le transport r & eacute;gulier de colluvions fertiles vers l'aval de la vall & eacute;e. Les facteurs potentiels de l'intensification agricole sont abord & eacute;s.