**1.2. St. Jones River Watershed**

This largely semi-pristine forested watershed provides many recreational activities, and therefore varying degrees of anthropogenic effects disturb the ecosystem. Monitoring the Blackbird Creek Reserve has been on-going since mid-1970 for the detection of ecosystem changes and established management practices. Blackbird Creek is a part of the Delaware National Estuarine Research Reserve (DNERR) which is associated with the NOAA for maintaining the estuarine system. Just over a decade ago, the Delaware Department of Natural Resources and Environmental Control (DNREC) identified that roughly 36.1% of the watershed is designated for agricultural use, and an additional 13.2% for urban use [19]; **Figure 1**. However, based on more current data from the Delaware Geospatial Exchange, approximately

The Blackbird Creek tidal marsh ecosystem is dominated by various salt marsh grasses and macro fauna. Similar to many estuaries in the United States, this ecosystem is threatened by the surrounding land-use activities especially agricultural and residential activities [12].

**Figure 1.** Land use practices in Blackbird Creek, Delaware, as described by LSPC Model Segmentation (map copied from

Stone 2016, map by DNREC [19].

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Stone [2] reported how population growth and land-use changes put pressure on ecosystems. As the population increases, more land is cleared for development and agricultural purposes. Increased impervious surfaces from roads, parking lots, and other infrastructure can prohibit rain from entering the soil system. This can result in the conversion of the rainfall to runoff,

44% of the watershed is designated to agriculture and only about 4% to urban use.

The St. Jones River Watershed, located in central Kent County, covers 23, 327 ha (57,643 ac). This 16-km long river extends from Silver Lake Dam to the Delaware Bay. The St. Jones Reserve, part of DNERR land, covers 1517 ha (3750 ac) and is located in the lower part of this watershed and features tidal brackish-water and salt marshes dominated by salt marsh salt hay (*Spartina patens*), cordgrass (*S. alterniflora*), and open water of creek, river, and bay areas, buffered by farmlands, freshwater-wooded fringe, and meadows but urbanized at upstream non-tidal areas [38]. It consists of three of the four hydro-geomorphic regions: poorly drained uplands, well-drained uplands, and beaches/tidal marshes/lagoons/barrier islands [39]. In the St. Jones Watershed, 39% of wetlands are tidal salt or brackish marshes, 35% are freshwater flats and 24% are riverine wetlands, and less than 2% are freshwater tidal or depressions [40]. There are several unique and threatened wetland features including bald cypress, Atlantic white cedar, and coastal plain ponds [40].

Agriculture and developed land in the St. Jones Watershed comprise almost 70% of the entire watershed's acreage. **Figure 2** shows the distribution of land use across the watershed from the National Land Cover Dataset (NLCD). Agricultural land and non-tidal wetlands are spread throughout the watershed. While forested patches are mainly located in the northern portion, large areas of tidal wetlands occur in the southeastern portion of the watershed. Since 2002, this watershed has experienced significant changes in land use and cover. The conversion of farmed land into residential housing led to a 6.1% increase in developed land and a 6.5% decrease in agricultural land. There were also losses in freshwater wetlands, particularly in non-tidal forested and scrub-shrub wetland habitats [41].

**Figure 2.** Land cover for the St. Jones River Watershed in 2007 based on National Land Cover Dataset (NLCD) land use categories [42].

Water quality problems in the St. Jones Watershed are attributed to sediment, nutrient, and chemical runoff [39]. Non-point pollution sources including runoff are mainly from roads (potentially containing oil, antifreeze, salt, and/or gas), lawn fertilizers and pesticides, and so on, dominate the St. Jones Watershed. Wastewater from septic systems is a source of nutrients in groundwater [39]. Moreover, channelization and ditching for agriculture and mosquito control led to altered natural wetland functions [39]. In addition, the invasive species such as *P. australis* have spread throughout fresh to brackish wetlands [39].

Reserve, part of DNERR land, covers 1517 ha (3750 ac) and is located in the lower part of this watershed and features tidal brackish-water and salt marshes dominated by salt marsh salt hay (*Spartina patens*), cordgrass (*S. alterniflora*), and open water of creek, river, and bay areas, buffered by farmlands, freshwater-wooded fringe, and meadows but urbanized at upstream non-tidal areas [38]. It consists of three of the four hydro-geomorphic regions: poorly drained uplands, well-drained uplands, and beaches/tidal marshes/lagoons/barrier islands [39]. In the St. Jones Watershed, 39% of wetlands are tidal salt or brackish marshes, 35% are freshwater flats and 24% are riverine wetlands, and less than 2% are freshwater tidal or depressions [40]. There are several unique and threatened wetland features including bald cypress, Atlantic

Agriculture and developed land in the St. Jones Watershed comprise almost 70% of the entire watershed's acreage. **Figure 2** shows the distribution of land use across the watershed from the National Land Cover Dataset (NLCD). Agricultural land and non-tidal wetlands are spread throughout the watershed. While forested patches are mainly located in the northern portion, large areas of tidal wetlands occur in the southeastern portion of the watershed. Since 2002, this watershed has experienced significant changes in land use and cover. The conversion of farmed land into residential housing led to a 6.1% increase in developed land and a 6.5% decrease in agricultural land. There were also losses in freshwater wetlands, particularly

**Figure 2.** Land cover for the St. Jones River Watershed in 2007 based on National Land Cover Dataset (NLCD) land use

white cedar, and coastal plain ponds [40].

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categories [42].

in non-tidal forested and scrub-shrub wetland habitats [41].

Rogerson et al. [42] reported that tidal sites with higher wetland condition scores resulted in lower avian species richness composed of primarily wetland-specific species, based on the intensive surveys of the avian community and vegetative biomass. Unfortunately, large areas of headwater flats in St. Jones River Watershed have been lost due to mainly agricultural production and development. According to Rogerson et al. [42] "Thirty-five percent of wetlands across the watershed were flats and had an average condition of 81, ranging from 57 to 94. Using condition categories, 37% of flat wetlands were minimally stressed, 47% were moderately stressed, and 16% were severely stressed." Over the last 50 years, over half (53%) of the 1385 ha of flats had not been forested (e.g., clear-cut, selective cut). As stated by Rogerson et al. [42], "Flats in higher condition had minimal garbage or dumping, low coverage by invasive plants, minimally altered micro-topography, and had a low occurrence of wetland ditching." Based on their assessment, forestry activity including cutting and harvesting within wetlands, and development and agriculture in buffers seem to be the major source of stressors in the watershed. Per Rogerson et al. [42], "Riverine wetlands, found adjacent to streams and rivers, accounted for 24% of the watershed's wetland acreage and had an average condition score of 72. Over half (55%) were considered minimally stressed, with low occurrences of invasive species, fill, and ditching, but frequently had dumping in addition to development and roads in the buffer. The severely stressed portion (10%) had condition scores as low as 27, related to the high prevalence of forestry activity, dumping, fill, storm water inputs and development within the buffer." They noted that wetlands with greater condition scores result in greater amounts of total-below ground biomass and a greater ratio of total-above-to-total-below ground biomass. Developmental activities such as residential, commercial, and/or transportation in the 100-m assessment site buffer were strongly related to the occurrence and frequency of wetland stressors such as storm water inputs, garbage, dumping, and invasive plants.

The watershed wetland condition report by Rogerson et al. [42] provided site-specific recommendations to improve wetland management, maximize natural benefits of tidal and non-tidal wetlands, and encourage informed decisions concerning the future of wetlands in Delaware. Previous research by Tiner [41] confirmed that the Delaware Bay basin was converted significantly to agriculture and residential development, particularly in non-tidal forested and scrub-shrub wetland habitats in St. Jones River Watershed. Emergent tidal wetland losses resulted in the excavation and filling of hydric sediments and the creation of impoundments [41]. As stated by Rogerson et al. [42], changes in land-cover and land-use patterns, especially near wetlands, are important to consider when evaluating wetland condition and its health.
