3.2 Federal Wetland Protections Vary as a Function of Wetland Size and Landscape position
Wetlands are unevenly distributed across the landscape, both in terms of individual wetland size and the position of wetlands in relation to stream networks. The size-frequency relationship of wetlands tends to follow a power-law distribution, with smaller wetlands occurring orders of magnitude more frequently on the landscape than comparatively larger wetlands (Van Meter & Basu, 2015). This relationship holds for NYS, where 73.2% of unique wetlands are smaller than 1 ha in size (Figure 3). However, while the majority of New York wetlands are relatively small, the largest proportion of total wetland area is concentrated amongst a limited number of large wetlands. Although wetlands larger than 30 ha make up only 1.1% of NYS wetlands by number, they represent 44.2% of total wetland area (Figure 3).
The position of wetlands in relation to the nearest jurisdictional water also follows a skewed distribution (Figure 3). Of NYS’s wetlands, 52.8% of unique wetlands and 84.7% of total wetland area are located within 100 ft (30.5 m) of the stream network. We also observe that wetlands located at greater distances from the stream network tend to be smaller in area than those positioned near streams (Figure 4). While most of New York’s wetlands are relatively small and located across a wide range of distances from the stream network, the majority of total wetland area is concentrated near the stream network, contributed by large wetlands.
We observe that both the CWR and NWPR preferentially protect wetlands in close proximity to the stream network, though this phenomenon is more pronounced for the NWPR (Figure 4). Within 100 ft (30.5 m) of the stream network, the CWR protects 100% of NYS wetlands by rule, representing over 740,000 ha of total wetland area. Of wetlands located between 100 and 4000 ft (30.5 and 1219.2 m) from streams, 14.1% of unique wetlands (23.4% of total area) are afforded jurisdictional status by the CWR while the remaining 85.9% of unique wetlands (76.6% of total area) require further evaluation under the significant nexus test. With its requirement of a surface-water connection, the NWPR considerably narrows the extent of protected wetlands toward the stream network. In direct comparison to the CWR, the NWPR protects only 74.4% of wetlands (92.1% of total area) within 100 ft (30.5 m) of the jurisdictional stream network and no wetlands outside of 100 ft (30.5 m). Despite these decreases, the NWPR still protects roughly 690,000 ha of wetlands within 100 ft (30.5 m) of the stream networks.
Coupled with the distribution of wetlands on the landscape, these geographic patterns result in distinct biases in the sizes of wetlands conserved (Figures 4 and 5). Under both rules, larger wetlands are considerably more likely to be classed as jurisdictional, while comparatively smaller wetlands tend to fall into the significant nexus or non-jurisdictional categories. Of wetlands larger than 30 ha, 99.0% and 96.2% of wetland area are jurisdictional under the CWR and NWPR, respectively. By comparison, wetlands smaller than 1 ha received markedly less protection, with only 57.8% and 36.9% of wetland area considered jurisdictional by rule under the CWR and NWPR, respectively. With decreasing wetland size, wetlands become increasingly dependent on the CWR significant nexus test to receive legal protection (Figure 5). Roughly 43% of wetlands smaller than 1 ha required the application of the significant nexus test under the CWR, compared to 0.99% of wetlands larger than 30 ha. We note that this size bias has little effect on the total area of wetlands protected, as small but numerous wetlands contribute a relatively small proportion of wetland area.