The Laguna de Santa Rosa watershed is historically a diverse mixture of oak woodland, grasslands, riparian forests, vernal pools and wetlands. Over recent years, the Laguna watershed has undergone profound anthropogenic changes resulting in increased sediment and nutrient loading, profound impacts to the natural flood cycles, habitat fragmentation, and vegetation shifts from native to invasive weed species. Coinciding with these changes has been increased nutrient and sedimentation loads from the Laguna to the Russian River.

Current land use of the watershed consists of urban and rural areas that include approximately 5.5 thousand acres of vineyards, 4 thousand acres of pasture, 2.8 thousand acres of dairies, and 1.3 thousand acres of mixed agriculture. Land-use within the 100-year floodplain includes a wastewater treatment facility, beef cattle, dairies, pastures, vineyards, and poultry. We estimate from analysis of remote sensing images of the Laguna de Santa Rosa floodplain that the rainfall events of winter 2006 inundated just over 3.35 thousand acres of land, 42% of which was pasture (much of it irrigated in the summer months with organic manure slurry), 24% was vineyard, and 26% was natural woodland and grassland cover.

Coverage patterns of this recent flood event suggest that large tracts of managed pasture and vineyard growing lands that receive regular fertilizer nutrient additions can be completely inundated with Laguna flood waters during years like 2006. These flood waters then recede slowly back into the Laguna main channel, potentially with an altered chemical composition resulting from prolonged contact with the soils of pastures and vineyards.