Freshwater wetlands have been shown to be extremely efficient at removing nitrate in watersheds where fertilizer runoff is high due to corn-soybean cultivation. Vegetation in these wetlands typically consists of dense monocultures of aggressive species such as narrow leaf and hybridized cattails, i.e. Typha spp. which can tolerate the dual stressors of high nitrate inputs and highly variable flow. Typha spp. in particular are highly productive and form thick, dense detrital mats, creating a region outside of the sediment which is rich in organic carbon and replete in oxygen and thus, potentially favorable for denitrification. Because of this, we asked if the growth of dense, mat-forming vegetation such as Typha in agriculturally impacted wetlands creates a negative feedback mechanism well adapted to regulate nitrate export. Through field sampling in two wetlands over six dates, we quantified denitrification rates by location, substrate, plant functional group, concentrations of nitrate and dissolved organic carbon and inflow nitrate load within wetlands. We used a mass balance approach to estimate overall contributions of denitrification occurring on detrital and sediment substrates and associated with emergent vegetation to wetland nitrate removal. We found denitrification rates, normalized by area, were highest for sediment, followed by detritus then live surfaces, and were linearly related to nitrate concentration for all substrates within the wetlands. Denitrification on detritus accounted for up to 20 % of nitrate removal. Concentrations of nitrate and dissolved organic carbon were tightly and inversely related across sampling events and both wetlands, suggesting microbial control of C:N where N was present and indicating plant-derived resources were in ample supply.