Macroinvertebrate Monitoring in the National Capital Region Network: Summary Report 2019–2022
Please cite this publication as:
Hilderbrand, R.H. 2026. Macroinvertebrate Monitoring in the National Capital Region Network: Summary Report 2019–2022. Science Report NPS/SR—2026/492. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2318683
Abstract
I synthesized and analyzed data from the National Park Service, National Capital Region Inventory and Monitoring Network (NCRN I&M) database for stream biota monitoring collected between 2019 and 2022. I assessed the ecological condition of streams and changes through time using the benthic macroinvertebrate data to calculate the Maryland Benthic Index of Biotic Integrity (BIBI) and its associated metrics. I also explored the BIBI and benthic macroinvertebrate community data for linkages to watershed attributes and human influences to better inform management. I analyzed water quality and steam physical habitat data such that each stream’s attributes were placed in the context of peer streams having similar land use, size, and geographic region.
Ecological condition and community structure are strongly tied to levels of watershed protection and disturbance. As watershed impervious surface cover (ISC) or population density increased, ecological condition decreased. Conversely, ecological condition increased as either the percentage of NPS ownership or the percentage of the watershed that is protected increased. Patterns in benthic macroinvertebrate community structure were clearly evident when these same variables were analyzed using ordination plots. The results highlight the importance of watershed protection to limit stream degradation.
Most streams in the National Capital Region Network rate as ecologically “poor or very poor” on the BIBI and are likely influenced by the human activities in most of the watersheds. While their overall condition is degraded, when compared against peer streams of similar size, urbanization levels, and geography that are not protected by NPS status, many NPS streams rank in the upper 25% for the BIBI, its component metrics, and stream physical habitat attributes. Thus, many NCRN I&M streams may be degraded by the surrounding human landscape, but they fare better than their peers under similar settings.
The ecological condition of many streams has declined in the most recent round of sampling compared to previous rounds. Some of the degradation may be attributed to a methods change implemented to capture more aquatic biodiversity and the necessary estimation of condition to make the results more compatible with prior monitoring. A better understanding of trends will be more evident with the next round of monitoring. There is variation in the responses both within and across streams and parks and no discernable geographic trends.
Brief synopses for streams in each park are provided for more detail.
NPS
Acknowledgments
Many thanks to all the NPS NCR staff for their support, ideas, and patience.
List of Acronyms
ANTI: Antietam National Battlefield
BIBI: Benthic Index of Biotic Integrity
CATO: Catoctin Mountain Park
CHOH: Chesapeake and Ohio Canal National Historical Park
EPT: Ephemeroptera, Plecoptera, and Trichoptera
GWMP: George Washington Memorial Parkway
HAFE: Harpers Ferry National Historical Park
I&M: Inventory and Monitoring
ISC: Impervious surface cover
MANA: Manassas National Battlefield Park
MBSS: Maryland Biological Stream Survey
MONO: Monocacy National Battlefield
NACE: National Capital Parks-East
NCR: National Capital Region
NCRN: National Capital Region Network
NMS: Non-metric multidimensional scaling
NPS: National Park Service
PRWI: Prince William Forest Park
ROCR: Rock Creek Park
WOTR: Wolf Trap National Park for the Performing Arts
Data & Code Availability
- Hilderbrand, R., M. Peipoch, M. Norris, and G. Sanders. 2026. National Capital Region Network Biological Stream Survey Data Package - cumulative through 2022. National Park Service. Fort Collins, Colorado. https://doi.org/10.57830/2318473
- Myers, D.T., R. Hilderbrand, and E. Brentjens. 2026. Supplemental information for biological stream survey report. National Park Service. Washington, DC. https://irma.nps.gov/DataStore/Reference/Profile/2318321
Introduction
Headwater streams within the national parks of the National Capital Region (NCR) are ecologically significant freshwater resources, yet they face increasing pressures from climate change, invasive species, and upstream human activities. The mandates of many historical parks, such as battlefields, further influence streams by maintaining the surrounding landscape in historical conditions less conducive to high ecological condition. Protecting these systems requires comprehensive monitoring programs that can detect ecological changes and assess ecosystem health to aid evidence-based management decisions. Benthic macroinvertebrates are commonly used as indicators of the biological condition in streams due to their sensitivity to environmental stressors and diverse assemblages that reflect varying levels of water quality and habitat integrity (Bonada et al. 2006). As integral components of aquatic food webs, these organisms serve as crucial links between primary producers and higher trophic levels, making their community structure and abundance essential indicators of overall ecosystem functioning and condition.
The National Park Service (NPS) Inventory and Monitoring (I&M) Division was established to provide scientific data necessary for informed resource management decisions across the diverse array of park units throughout the United States (U.S. National Park Service 2024). Stream biota monitoring was incorporated into the NPS National Capital Region (NCR) I&M Network with a pilot monitoring phase from 2004 to 2006 (Hilderbrand et al. 2005) and a protocol finalized in 2009 (Norris and Sanders 2009). These I&M efforts enable park managers to understand both local and regional trends in aquatic ecosystem conditions, identify emerging threats, and evaluate management effectiveness. The NPS NCR I&M Network has conducted two full rounds of sampling since inception and can now provide a larger-scale view of factors influencing ecological condition in NPS streams.
The parks (and their streams) within the NCR span a diverse gradient from the Appalachian Mountains eastward through the Eastern Piedmont and on to the Atlantic Coastal Plain. Land uses range from forest parks (Catoctin Mountain Park, Prince William Forest Park), to agricultural landscapes (Antietam National Battlefield), to highly urbanized areas (Rock Creek Park, National Capital Parks - East). Headwater streams within NCR parks thus have substantial diversity in their physical, chemical, and biological characteristics, reflecting the varied geological, climatic, and elevational gradients represented across the region. Benthic macroinvertebrate monitoring efforts focus on measuring the ecological condition of the stream ecosystems in parks, providing standardized assessments that can detect changes in community composition that may indicate shifts in ecosystem processes or stresses. The taxonomic resolution and ecological sensitivity of benthic macroinvertebrate communities make them particularly valuable for detecting ecosystem degradation and identifying situations where conditions may be changing (Kenney et al. 2009).
The synthesis of benthic macroinvertebrate monitoring data from streams across the NCR Network (NCRN) represents an important step toward identifying and understanding broad-scale patterns in ecological condition and identifying system-wide patterns and conservation priorities. These data help managers understand the condition and trends of park streams and identify potential stressors to these valuable resources, while simultaneously contributing to our scientific understanding of how protected aquatic ecosystems respond to regional and global environmental changes. This comprehensive analysis of multi-year monitoring datasets provides an opportunity to evaluate the effectiveness of current management strategies, assess the vulnerability of different stream types to various stressors, and establish baseline conditions against which future changes can be measured. By examining patterns across multiple parks, one might identify both common threats and unique conservation challenges that require targeted management approaches to improve the long-term protection of these public resources.
This report has several objectives. A primary objective is an overall assessment of current stream ecological conditions as derived from benthic macroinvertebrates and if there have been changes compared to previous monitoring. The overall assessment should be valuable to anyone reading this report and could help parks focus resources and attention on specific streams. A related objective informs resource management at all levels by analyzing benthic macroinvertebrate community structure and relating this to watershed attributes such as ownership and land uses. Finally, a peer stream analysis was performed to compare each NPS stream against regional streams in similar settings. The results are intended to inform park staff about the ecological condition of their streams given the constraints imposed by mandated land uses and other factors. This last objective is not meant to be a sugar coating of stream conditions or relieving of responsibilities. Rather, this provides a way of assessing whether degraded streams in parks are similar to other streams under similar landscape settings or if the NPS streams are actually doing better than expected given their constraints.
Methods
Sites
NCRN I&M monitors 37 streams located within 10 parks (Table 1). Streams were selected by NPS during the pilot monitoring phase, 2004–2006. Most original sites have been sampled two times in subsequent years, but some were dropped and new sites have been added. This report includes only sites sampled in the most recent sampling round from 2019 to 2022. Each site was sampled for benthic macroinvertebrates with a D-Net following the protocols in Norris and Sanders (2009). Briefly, 10 square feet of substrate was sampled within the selected 75 m reach. Riffle habitats were prioritized because these contain the most benthic macroinvertebrate diversity, and other habitats were sampled in proportion to their abundances within the reach. During the same visit, stream physical habitat was evaluated using NCRN protocols (Norris and Sanders 2009). Descriptions of the habitat measures are listed in Table 2. Samples were collected during a spring period between March 1 and April 30.
| Park | Site | Stream | Region | Year Sampled | Order | Area (ha) | % NPS Owned |
% Urban | % ISC | % Protected Lands | Population Density (persons / ha) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| ANTI | NCRN_ANTI_SHCK | Sharpsburg Creek | HIGHLAND | 2022 | 1 | 331 | 24 | 40 | 9 | 55 | 3 |
| CATO | NCRN_CATO_BGHC | Big Hunting Creek | HIGHLAND | 2022 | 3 | 2231 | 25 | 2 | 0 | 58 | 0 |
| CATO | NCRN_CATO_BLBZ | Blue Blazes Creek | HIGHLAND | 2022 | 1 | 219 | 100 | 0 | 0 | 100 | 0 |
| CATO | NCRN_CATO_OWCK | Owens Creek | HIGHLAND | 2022 | 2 | 724 | 64 | 3 | 1 | 64 | 0 |
| GWMP | NCRN_GWMP_MICR | Minnehaha Creek | EPIEDMONT | 2022 | 2 | 350 | 0 | 79 | 21 | 3 | 15 |
| GWMP | NCRN_GWMP_MIRU | Mine Run | EPIEDMONT | 2022 | 3 | 650 | 5 | 22 | 4 | 8 | 2 |
| GWMP | NCRN_GWMP_PIRU | Pimmit Run | EPIEDMONT | 2022 | 3 | 2778 | 2 | 80 | 24 | 9 | 17 |
| GWMP | NCRN_GWMP_TURU | Turkey Run | EPIEDMONT | 2022 | 2 | 269 | 50 | 36 | 8 | 52 | 4 |
| HAFE | NCRN_HAFE_FLSP | Flowing Springs Run | HIGHLAND | 2022 | 2 | 2118 | 3 | 33 | 13 | 5 | 3 |
| MANA | NCRN_MANA_YOBR | Young’s Branch | EPIEDMONT | 2022 | 3 | 1714 | 71 | 15 | 9 | 70 | 0 |
| MONO | NCRN_MONO_BUCK | Bush Creek | EPIEDMONT | 2022 | 4 | 8244 | 1 | 24 | 7 | 6 | 3 |
| MONO | NCRN_MONO_GAMI | Gambrill Mill Creek | EPIEDMONT | 2022 | 2 | 263 | 21 | 27 | 5 | 20 | 3 |
| NACE | NCRN_NACE_HECR | Henson Creek | COASTAL | 2022 | 2 | 964 | 8 | 65 | 40 | 25 | 18 |
| NACE | NCRN_NACE_OXRU | Oxon Run | COASTAL | 2022 | 3 | 3392 | 7 | 74 | 39 | 12 | 33 |
| NACE | NCRN_NACE_STCK | Still Creek | COASTAL | 2022 | 2 | 964 | 55 | 38 | 23 | 54 | 12 |
| PRWI | NCRN_PRWI_BONE | Boneyard Run | EPIEDMONT | 2021 | 1 | 47 | 96 | 0 | 0 | 74 | 0 |
| PRWI | NCRN_PRWI_CARU | Carter’s Run | EPIEDMONT | 2021 | 1 | 36 | 93 | 1 | 2 | 100 | 0 |
| PRWI | NCRN_PRWI_MARU | Mawavi Run | EPIEDMONT | 2021 | 1 | 27 | 100 | 0 | 0 | 100 | 0 |
| PRWI | NCRN_PRWI_MBBR | Mary Byrd Branch | EPIEDMONT | 2021 | 2 | 206 | 100 | 0 | 0 | 100 | 0 |
| PRWI | NCRN_PRWI_NFQC | North Fork Quantico Creek | EPIEDMONT | 2021 | 2 | 1782 | 97 | 2 | 1 | 90 | 0 |
| PRWI | NCRN_PRWI_ORRU | Orenda Run | EPIEDMONT | 2021 | 1 | 51 | 95 | 1 | 3 | 46 | 0 |
| PRWI | NCRN_PRWI_SFQC | South Fork Quantico Creek | EPIEDMONT | 2021 | 3 | 4328 | 59 | 1 | 1 | 95 | 0 |
| PRWI | NCRN_PRWI_SORU | Sow Run | EPIEDMONT | 2021 | 2 | 344 | 100 | 0 | 0 | 100 | 0 |
| PRWI | NCRN_PRWI_TARU | Taylor Run | EPIEDMONT | 2021 | 1 | 122 | 100 | 0 | 0 | 100 | 0 |
| ROCR | NCRN_ROCR_BAKE | Battery Kemble Creek | EPIEDMONT | 2019 | 1 | 69 | 38 | 53 | 13 | 69 | 17 |
| ROCR | NCRN_ROCR_BRBR | Broad Branch | EPIEDMONT | 2019 | 2 | 667 | 14 | 79 | 29 | 16 | 37 |
| ROCR | NCRN_ROCR_DUOA | Dumbarton Oaks | EPIEDMONT | 2019 | 1 | 80 | 23 | 67 | 32 | 47 | 17 |
| ROCR | NCRN_ROCR_FEBR | Fenwick Branch | EPIEDMONT | 2019 | 2 | 404 | 4 | 95 | 44 | 5 | 56 |
| ROCR | NCRN_ROCR_KLVA | Klingle Valley Creek | EPIEDMONT | 2019 | 1 | 51 | 1 | 97 | 41 | 1 | 56 |
| ROCR | NCRN_ROCR_LUBR | Luzon Branch | EPIEDMONT | 2019 | 1 | 266 | 11 | 91 | 47 | 14 | 61 |
| ROCR | NCRN_ROCR_NOST | Normanstone Branch | EPIEDMONT | 2019 | 1 | 102 | 10 | 84 | 33 | 22 | 20 |
| ROCR | NCRN_ROCR_PHBR | Pinehurst Branch | EPIEDMONT | 2019 | 1 | 268 | 22 | 75 | 16 | 22 | 19 |
| ROCR | NCRN_ROCR_PYBR | Piney Branch | EPIEDMONT | 2019 | 1 | 991 | 7 | 94 | 57 | 7 | 75 |
| ROCR | NCRN_ROCR_R630 | Reservation 630 | EPIEDMONT | 2019 | 1 | 93 | 22 | 74 | 32 | 21 | 43 |
| ROCR | NCRN_ROCR_ROC3 | Rock Creek | EPIEDMONT | 2022 | 4 | 19626 | 5 | 65 | 25 | 24 | 22 |
| WOTR | NCRN_WOTR_CHCK | Courthouse Creek | EPIEDMONT | 2022 | 1 | 407 | 1 | 77 | 43 | 7 | 11 |
| WOTR | NCRN_WOTR_WOTR | Wolf Trap Creek | EPIEDMONT | 2022 | 2 | 1434 | 3 | 74 | 30 | 8 | 12 |
| Habitat Metric | Rating (Low–High) |
Description |
|---|---|---|
| Velocity/Depth Diversity | 0–20 | Variety of velocity/depth regimes |
| Riffle Quality | 0–20 | Depth, complexity, and functional importance of riffle/run habitats |
| Pool Quality | 0–20 | Variety and complexity of slow or still water habitats |
| Instream Habitat | 0–20 | Perceived quality of fish habitat |
| Epifaunal Substrate | 0–20 | Amount and variety of stable substrates usable by benthic macroinvertebrates |
| Embeddedness | 0–100 | Percent of coarse riffle substrates surrounded by fine material |
The data from the most recent round was incorporated into a master dataset compiled and maintained by NCRN I&M and containing all of the NPS stream biota monitoring data collected to date (Hilderbrand et al. 2025).
The number of individuals identified for each benthic macroinvertebrate sample was increased to 200 in the latest sampling round compared to the samples collected before 2019, which identified only 100 individuals. The increase was instituted to more fully capture the biodiversity in NPS streams. A resampling routine was implemented to estimate the Maryland Benthic Index of Biotic Integrity (BIBI) scores for a 100-individual count for the most recent monitoring samples.
Peer Stream Selection and Analysis
An analysis was designed to compare each NPS site against non-NPS streams sampled by the Maryland Biological Stream Survey (MBSS; https://dnr.maryland.gov/streams/Pages/dataRequest.aspx) that were matched for size, land uses, and geographic region. Although many of the NPS sites are not located within Maryland, they are nearby, and the Maryland sampling methodologies have been adopted for stream biological monitoring. The peer streams were identified to provide a more realistic comparison to streams existing under similar conditions rather than comparing NPS streams against least-disturbed streams in forested landscapes. It was deemed nonsensical to only compare NPS streams in landscapes with human-modified conditions against least-disturbed conditions. This approach recognizes degradation where it exists, yet also evaluates streams within their constraint context.
Each site was matched with MBSS peer streams based on several factors. NPS NCR provided attributes for each of the NPS stream watersheds, whereas MBSS stream characters were pulled directly from the MBSS database. A simple filtering approach was used so that all streams in the MBSS database meeting selection criteria for each NPS monitoring site were selected. Peer streams were drawn from the same geographic region, and their size had to fall within ±1 stream order of the NPS site. Watershed area was initially tried instead of stream order, but there was too much variation in stream size due to geography and hydrography. The percentage of agricultural land uses in the watershed (Dewitz 2021) was binned into low (<20% land cover) and high (>20% land cover). Watershed urbanization (Dewitz 2021) was binned into low (<15% land cover) and high (>15% land cover). At least 10 peer streams were matched to each NPS site with the exceptions of Monocacy National Battlefield (MONO) Bush Creek (n = 7) and Rock Creek Park (ROCR) Dumbarton (n = 4). For a full list of park acronyms and definitions used throughout this report, see the List of Acronyms.
A full list of the peer streams and associated data that were used for the analysis can be found in the Dataset “Supplemental Information for Biological Stream Survey Report” available on the NPS DataStore at: https://irma.nps.gov/DataStore/Reference/Profile/2318321.
All of the ecological and stream physical habitat attributes at each site were compared against the data distribution of values for the peer sites, and the percentile ranking within the distribution calculated for that specific attribute. The results then allowed for an assessment of each attribute for each NPS site compared to other streams with similar size and land use attributes.
Data Analyses
The benthic macroinvertebrate data were used to calculate the Maryland Benthic Index of Biotic Integrity (BIBI; Stribling et al. 1998) and its component metrics for each of the samples collected for each year of the monitoring, 2006–2022. The BIBI is a composite index produced from component metrics identified to reflect the ecological condition of streams. The BIBI has slight differences in component metrics across the Highlands, Eastern Piedmont, and Coastal Plain regions because there are regional differences in benthic macroinvertebrate genera and their abilities to reflect ecological condition (Stribling et al. 1998). Although many of the streams in this report are located outside of Maryland, the same BIBI has been used for consistency. All streams fall within the same geographic regions used by BIBI analysis, and the NPS NCR region methodology is based on the MBSS protocols. The R package MBSStools (Leppo 2021) was used to calculate the BIBI and component metrics for each of the sites.
The MBSS implementation of the BIBI uses data generated from a 100-individual subsample, and NPS samples prior to 2019 were constructed from these 100 subsample counts. The latest sampling round beginning in 2019 constructed samples based on 200 individual subsamples. This was an intentional change moving forward to identify more aquatic biodiversity and better characterize the benthic macroinvertebrate communities in the parks. Increasing from 100 to 200 individuals increases the total numbers of genera within a sample, which will produce artificially higher BIBI scores compared to the calculations from previous monitoring rounds. To make the samples more comparable, a bootstrapped resampling technique was used to calculate BIBI scores for the 200 count samples. The routine randomly selected 100 individuals from each of the samples collected 2019–2022 and calculated the BIBI. This was implemented 1,000 times for each sample and the mean and 95% confidence interval were calculated. The mean value was used for any analyses comparing changes through time. While rarefaction (another way of standardizing samples of different sizes) could have been used to estimate taxa richness from the 200 individual subsamples, it could not be used to calculate the numerous other BIBI metrics. As discussed in the results, taxa richness estimates generated by rarefaction were compared to the resampled estimates.
The ecological attributes comprising the BIBI were used in a linear models framework to explore relationships between ecological condition for each stream and the surrounding watershed settings provided by NPS NCR (Table 3) including: stream order, % watershed impervious surface cover (ISC), % NPS ownership, % protected lands, and population density. Population density was calculated by dividing the human population size data by the catchment area converted to hectares. These same ecological attributes calculated for the most recent round of sampling were compared against the most recent previous sampling, to identify if conditions have improved, declined, or remained similar. For those attributes where a larger number is a negative indicator (e.g., % Chironomidae), the data were rescaled so they would move in the same direction as the other indicators. Differences were calculated as the percent change in an attribute with any values greater than 100% capped at 100% for display purposes. Given the variation in environmental data, only differences exceeding ±30% were considered ecologically meaningful.
| Characteristic | Dataset | Column Name in Dataset | Filename from Which Column Was Calculated | Source Data Provider or Description |
|---|---|---|---|---|
| Catchment area acres | bss_loc_lookup.csv | Catchment_Area_Acres | ||
| % Watershed impervious surface cover | bss_loc_lookup.csv | Watershed_Percent_Impervious_NLCD2019 | ||
| % NPS ownership | bss_loc_lookup.csv | NPS_Watershed_Ownership_Percent | ||
| % Protected lands | bss_loc_lookup.csv | Watershed_Protected_Area_Percent_PAD | ||
| Stream order | nps_stream_order.csv | Stream_Order | ||
| Human population size in a watershed | bss_loc_lookup.csv | Watershed_Landscan_Population_Sum |
In addition to the BIBI and component metrics, benthic macroinvertebrate communities were explored with non-metric multidimensional scaling ordination. Patterns in community structure in relation to the landscape and land use attributes were plotted on the ordinations as well as formally assessed using Adonis in the Vegan package (Oksanen et al. 2024) in R 4.4.2 (R Core Development Team 2025). All results were considered statistically significant at P = 0.05.
Results and Discussion
National Capital Region parks are embedded within a highly human-modified landscape, and the ecological condition of their streams reflects this. The overall general condition seems to have decreased since previous rounds of sampling. Yet, many streams in the NCR I&M Network compare favorably to peer streams in the region after matching to similar landscapes. As detailed below, ecological condition and biotic community structure are strongly related both to the amount of impervious surface cover (ISC) and human population (negative) in the upstream watershed and to the amount of the watershed that is protected (positive). This leads to the idea that even in more urbanized areas, streams with greater protection are more likely to have better ecological condition and a more “natural” appearance despite being degraded.
Current Ecological Condition Is Reduced by Human Activities and Mitigated with Land Protections
Stream ecological condition showed significant influences from the modern landscape. BIBI scores significantly decreased as the % ISC increased (regression; P < 0.001) or the human population density increased (regression; P = 0.001; Table 4). BIBI scores were not significantly influenced by stream order (P > 0.05). However, increasing the percentage of NPS-owned lands (regression; P < 0.001) and the overall percentage of protected lands (P < 0.001) in the watershed was associated with a significant increase in BIBI scores.
| Ecological Response | Predictor | Estimate | Std. Error | t-Value | df | P-Value |
|---|---|---|---|---|---|---|
| BIBI | % ISC A | −0.04 | 0.007 | −6.12 | 35 | <0.001 |
| % NPS A | 0.02 | 0.003 | 5.44 | 35 | <0.001 | |
| Stream Order | 0.16 | 0.188 | 0.83 | 35 | 0.411 | |
| Population Density A | −0.03 | 0.007 | −5.04 | 35 | <0.001 | |
| % Protected A | 0.02 | 0.004 | 5.52 | 35 | <0.001 | |
| EPT Richness | % ISC A | −0.17 | 0.027 | −6.48 | 35 | <0.001 |
| % NPS A | 0.06 | 0.014 | 4.36 | 35 | <0.001 | |
| Stream Order | 0.15 | 0.755 | 0.20 | 35 | 0.842 | |
| Population Density A | −0.12 | 0.028 | −4.17 | 35 | <0.001 | |
| % Protected A | 0.07 | 0.015 | 4.72 | 35 | <0.001 | |
| Total Richness | % ISC A | −0.16 | 0.050 | −3.24 | 35 | 0.003 |
| % NPS | 0.03 | 0.025 | 1.05 | 35 | 0.301 | |
| Stream Order | 1.88 | 1.034 | 1.82 | 35 | 0.077 | |
| Population Density A | −0.15 | 0.041 | −3.72 | 35 | 0.001 | |
| % Protected A | 0.03 | 0.027 | 0.97 | 35 | 0.338 | |
| % Urban Intolerant | % ISC A | −0.74 | 0.144 | −5.14 | 35 | <0.001 |
| % NPS A | 0.30 | 0.067 | 4.39 | 35 | <0.001 | |
| Stream Order | −0.19 | 3.613 | −0.05 | 35 | 0.959 | |
| Population Density A | −0.48 | 0.140 | −3.45 | 35 | 0.002 | |
| % Protected A | 0.31 | 0.073 | 4.32 | 35 | <0.001 |
A Values are statistically significant (also with a light gray background).
Other aspects of benthic macroinvertebrate biodiversity and sensitivity to humans followed similar patterns to ISC. Both the richness of the indicator group EPT (Ephemeroptera, Plecoptera, and Trichoptera) and the percent of urban intolerant taxa in a sample were strongly negatively related to watershed % ISC and population density, and they were positively related to the percentage of NPS ownership and overall percent of protected lands in the watershed (Table 4). While most EPT are also urban intolerant taxa, many intolerant taxa are not EPT, and the results suggest the negative aspects of % ISC and positive aspects of protected lands apply to diverse groups of taxa. Surprisingly, the overall total taxonomic richness was not associated with measures of watershed protection. However, taxonomic richness significantly decreased both with increasing levels of watershed % ISC and increasing population density. Stream order was not related to any of the ecological measures.
The actual BIBI scores calculated for each stream during the most recent monitoring (2019–2022) are mostly “poor” to “very poor” (Figure 1). These results are not surprising given the urban nature of most NCR parks and the relationships between ecological condition and human activities. Nonetheless, several streams rated as Fair and even Good. Most of the higher scoring streams are in less urban parks such as Catoctin Mountain Park and Prince William Forest Park. Specific metric values for each of the sites are presented later in the individual park synopses.
NPS / ROBERT HILDERBRAND
The ecological condition of most of the streams is like that of their peer streams after matching for similar region, size, and land use. Sites such as Oxon Run in the Coastal Plain (Table 5), Turkey Run in the Eastern Piedmont (Table 6), and Sharpsburg Creek in the Highland region (Table 7) are mostly worse than their peers for the BIBI and component metrics. However, a number of sites in more urbanized areas such as Rock Creek Park compare well with their peers even if they are more degraded than is desired (Figure 2). These more urbanized parks tend to have streams in better ecological condition than similarly matched streams in the region, and the protections afforded by being in a park likely explains much of that. However, the peer analysis comes with caveats because the results can be misleading for parks such as Catoctin Mountain Park and Prince William Forest Park where the streams have suitable ecological condition (i.e., Figure 1), but their matched peer streams may be even better. Thus, this plot should be seen as additional information about a stream, but not as the primary source for assessment.
| Park Unit | Site | Scraper Richness | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | Ephemeroptera Richness | % Climber | BIBI |
|---|---|---|---|---|---|---|---|---|---|
| NACE | Henson Creek | 69 | 61 | 77 | 65 | 64 | 50 | 69 | 55 |
| NACE | Oxon Run | 87 | 98 | 82 | 81 | 77 | 79 | 80 | 95 |
| NACE | Still Creek | 69 | 63 | 77 | 60 | 68 | 72 | 37 | 61 |
| Park Unit | Site | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|
| GWMP | Mine Run | 99 | 69 | 94 | 88 | 99 | 99 | 97 |
| GWMP | Minnehaha Creek | 91 | 79 | 80 | 73 | 68 | 90 | 95 |
| GWMP | Pimmit Run | 92 | 82 | 91 | 78 | 83 | 89 | 98 |
| GWMP | Turkey Run | 87 | 88 | 97 | 96 | 99 | 99 | 99 |
| MANA | Young’s Branch | 92 | 87 | 96 | 52 | 78 | 84 | 85 |
| MONO | Bush Creek | 100 | 89 | 99 | 91 | 99 | 100 | 100 |
| MONO | Gambrill Mill Creek | 73 | 63 | 91 | 56 | 85 | 91 | 79 |
| PRWI | Boneyard Run | 86 | 88 | 84 | 92 | 62 | 47 | 89 |
| PRWI | Carter’s Run | 98 | 88 | 90 | 93 | 34 | 36 | 84 |
| PRWI | Mary Byrd Branch | 95 | 48 | 61 | 23 | 8 | 18 | 39 |
| PRWI | Mawavi Run | 90 | 80 | 86 | 97 | 56 | 34 | 84 |
| PRWI | NF Quantico Creek | 99 | 95 | 98 | 70 | 8 | 19 | 88 |
| PRWI | Orenda Run | 98 | 82 | 96 | 92 | 74 | 45 | 93 |
| PRWI | SF Quantico Creek | 100 | 43 | 48 | 8 | 13 | 23 | 31 |
| PRWI | Sow Run | 97 | 72 | 88 | 52 | 74 | 75 | 82 |
| PRWI | Taylor Run | 75 | 79 | 49 | 29 | 48 | 36 | 50 |
| ROCR | Battery Kemble Creek | 97 | 97 | 99 | 97 | 100 | 100 | 100 |
| ROCR | Broad Branch | 85 | 28 | 22 | 0 | 28 | 48 | 6 |
| ROCR | Dumbarton Oaks | 93 | 77 | 48 | 14 | 83 | 29 | 88 |
| ROCR | Fenwick Branch | 90 | 79 | 78 | 22 | 79 | 81 | 96 |
| ROCR | Klingle Valley Creek | 72 | 77 | 30 | 0 | 66 | 45 | 36 |
| ROCR | Luzon Branch | 91 | 77 | 94 | 70 | 87 | 63 | 99 |
| ROCR | Normanstone Branch | 91 | 77 | 32 | 0 | 77 | 73 | 88 |
| ROCR | Pinehurst Branch | 84 | 77 | 63 | 0 | 71 | 44 | 65 |
| ROCR | Piney Branch | 97 | 77 | 62 | 3 | 63 | 30 | 88 |
| ROCR | Reservation 630 | 65 | 48 | 17 | 40 | 75 | 50 | 76 |
| ROCR | Rock Cr Dumbarton | 95 | 62 | 89 | 90 | 0 | 94 | 90 |
| WOTR | Courthouse Creek | 71 | 50 | 76 | 5 | 39 | 82 | 55 |
| WOTR | Wolf Trap Creek | 85 | 79 | 70 | 73 | 18 | 85 | 75 |
| Park Unit | Site | % Tanytarsini | % Swimmer | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | % Diptera | BIBI |
|---|---|---|---|---|---|---|---|---|---|
| ANTI | Sharpsburg Creek | 73 | 83 | 100 | 100 | 99 | 89 | 8 | 98 |
| CATO | Big Hunting Creek | 71 | 4 | 97 | 77 | 93 | 14 | 65 | 74 |
| CATO | Blue Blazes Creek | 77 | 37 | 98 | 59 | 89 | 57 | 93 | 91 |
| CATO | Owens Creek | 71 | 15 | 90 | 51 | 77 | 45 | 79 | 74 |
| HAFE | Flowing Springs Run | 76 | 66 | 94 | 80 | 93 | 73 | 73 | 96 |
NPS / ROBERT HILDERBRAND
It is important to realize that each estimate is derived from a subsample of suitable habitats collected in a 75 m stream reach. Each of these are further subsampled to 200 individuals. We assume that this sample is representative of the entire stream but must accept that there can be variation and randomness with any sample. Only higher sampling densities within a reach or along the entire stream length can provide the information to determine how representative a single sample is for the entire stream. NPS does not have the staffing or budget to allow such precision and uses each sample as the best possible representative of the site and perhaps the entire stream. This assumption also applies to comparing trends through time. Only after several rounds of sampling will a clearer picture of stream conditions and any changes emerge.
Current Ecological Condition Has Declined at Several Monitoring Sites
Given the caveats of the previous paragraph, changes in ecological condition for parks in the Coastal Plain (Figure 2), Piedmont (Figure 3), and Highland (Figure 4) regions show different aspects of how benthic macroinvertebrate attributes have changed from prior sampling to the most recent sampling (2019–2022). The overall trend is that ecological condition as assessed by the BIBI has declined at more sites than increased, with most remaining the same. Sites falling within the 0 ± 30% gray area are considered not to have changed because the differences are too small to be reliably detected and meaningful. The overall taxonomic richness and the BIBI have largely declined (but see caveat below), whereas the other metrics show varied responses. The declines seem to be across the NCR and not restricted to specific parks.
NPS / ROBERT HILDERBRAND
NPS / ROBERT HILDERBRAND
Stream-specific values for changes in each of the ecological attributes can be found in the discussions of each of the individual parks later in this report.
An important caveat to this analysis is that the number of individuals identified for each benthic macroinvertebrate sample was increased to 200 in the latest sampling round compared to the samples collected before 2019, which identified only 100 individuals. The increase was instituted to more fully capture the biodiversity in NPS streams moving forward. A resampling routine was implemented to estimate the BIBI scores for a 100-individual count for the most recent monitoring samples. The resampling routine tended to underestimate the total number of taxa by 1–2 genera on average compared to estimates using rarefaction. Thus, the BIBI scores for the latest monitoring round may be slight underestimates and may suggest decreases in ecological condition when there are none.
Community Structure Changes with Human Activities
The surrounding landscape and human population numbers had substantial influences on benthic macroinvertebrate community structure across NPS NCR I&M Network streams. The communities examined in 2004–2022 were significantly different at sites where the upstream watershed was less than 10% impervious surface cover (ISC) compared to sites with >10% ISC (ADONIS P < 0.001; Panel ISC Amount: All Years, Figure 5). The same pattern was observed with even greater differentiation when examining only the most recent monitoring round (ADONIS P < 0.001; Panel ISC Amount: 2019–2022, Figure 5); there is clear separation in the benthic communities at different levels of watershed ISC.
NPS / ROBERT HILDERBRAND
Similar, yet less visually striking results in community structure also emerged when the human population density within a watershed was above or below 5/ha for all years sampled (ADONIS P < 0.001; Panel Human Population: All Years, Figure 5) as well as for the most recent sampling round (ADONIS P < 0.001; Panel Human Population: 2019–2022, Figure 5).
The changes in community structure are consistent with prior research demonstrating substantial biodiversity loss as watersheds become urbanized and hardened with roads, parking lots, and other features that promote stormwater runoff and decrease infiltration (Utz et al. 2009). As watersheds harden, the streams generally experience more frequent and intense flooding (O’Driscoll et al. 2010) and increased delivery of sediments and human-related chemicals (Anh et al. 2023; Russell et al. 2018), which can stress the aquatic biota. Some macroinvertebrate taxa show negative effects in their occurrences at watershed impervious surface cover (ISC) levels >3% (Utz et al. 2009), and by 10% ISC, the communities are notably different from those in less disturbed watersheds (Schiff and Benoit 2007).
Community Structure Is Influenced by Land Protections
Benthic macroinvertebrate community structure changed as the amount of protected land within a watershed increased. There was a noticeable pattern in community structure when the NPS % ownership within a watershed was above or below 10% across the entire monitoring record (ADONIS P < 0.001; Panel NPS Ownership: All Years, Figure 6). The pattern became more pronounced when only the most recent round of sampling was examined (ADONIS P < 0.001; Panel NPS Ownership: 2019–2022, Figure 6). This same pattern was evident and perhaps more defined when considering all protected lands within the watershed for all years (ADONIS P < 0.001; Panel Protected Lands: All Years, Figure 6) and especially for the most recent sampling round (ADONIS P < 0.001; Panel Land Protections: 2019–2022, Figure 6).
NPS / ROBERT HILDERBRAND
The similarities among land protections, ISC, and population density are expected because they are all correlated. The greater the population density, the more likely ISC will be higher because of the infrastructure required to support society. Conversely, greater amounts of protected lands result in lower human population density and infrastructure.
Ecological Results Did Not Appreciably Change with the Increased Subsample Size
Because the samples collected 2019–2022 were sorted for 200 individuals rather than 100 as in the previous rounds, the community data were displayed and tested to assess differences. The 95% confidence ellipses for the samples collected prior to 2018 (blue) show considerable overlap with those collected 2019–2022 (red) and suggest similar community structure (Figure 7). However, the communities are statistically different (ADONIS P < 0.001) and are also different when comparing communities sampled 2012–2014 against those sampled 2019–2022 (ADONIS P = 0.001). This is likely due to the additional taxa identified in the 200-individual sorting, even if the overall structure has not appreciably changed in the plot. Despite the significant differences, the large overlap in Figure 7 suggests that any differences are more likely in the proportions of individual taxa rather than the occurrences of novel taxa.
NPS / ROBERT HILDERBRAND
Stream Physical Habitat Is Generally Adequate and Not Limiting Ecological Condition
Stream physical habitat conditions (Table 2; defined in Norris and Sanders 2009) within NPS NCR I&M Network streams were generally similar to, or better than, their peer streams (Table 8). Most streams had better riffle quality and similar pool quality, instream habitat, epifaunal substrate (quality habitats for benthic macroinvertebrates), and embeddedness (fine sediments) compared to peer streams. ROCR streams in particular tended to have good habitats compared to their urban peers. From a habitat perspective, the results suggest that the observed ecological responses are probably not limited by habitat and could be better were they not limited by other factors such as those associated with urbanized landscapes, increasing stream temperatures, or in some cases, by excess nutrients.
| Park Unit | Site | Velocity/ Depth | Riffle Quality | Pool Quality | Instream Habitat | Epifaunal Substrate | Embeddedness |
|---|---|---|---|---|---|---|---|
| ANTI | Sharpsburg Creek | 33 | 16 | 31 | 10 | 69 | 98 |
| CATO | Big Hunting Creek | 76 | 24 | 71 | 43 | 62 | 97 |
| CATO | Blue Blazes Creek | 83 | 37 | 81 | 91 | 69 | 100 |
| CATO | Owens Creek | 76 | 20 | 64 | 75 | 89 | 100 |
| GWMP | Mine Run | 89 | 5 | 91 | 35 | 38 | 53 |
| GWMP | Minnehaha Creek | 29 | 4 | 35 | 55 | 85 | 20 |
| GWMP | Pimmit Run | 28 | 14 | 69 | 78 | 63 | 45 |
| GWMP | Turkey Run | 8 | 4 | 58 | 59 | 77 | 66 |
| HAFE | Flowing Springs Run | 61 | 5 | 80 | 17 | 41 | 55 |
| MANA | Young’s Branch | 75 | 70 | 67 | 91 | 86 | 25 |
| MONO | Bush Creek | 100 | 12 | 100 | 53 | 95 | 72 |
| MONO | Gambrill Mill Creek | 85 | 29 | 86 | 86 | 77 | 89 |
| NACE | Henson Creek | 49 | 2 | 12 | 55 | 39 | 39 |
| NACE | Oxon Run | 58 | 9 | 42 | 67 | 19 | 53 |
| NACE | Still Creek | 14 | 4 | 30 | 36 | 10 | 39 |
| PRWI | Boneyard Run | 89 | 100 | 73 | 52 | 99 | 42 |
| PRWI | Carter’s Run | 58 | 62 | 10 | 74 | 50 | 72 |
| PRWI | Mary Byrd Branch | 31 | 42 | 46 | 11 | 34 | 27 |
| PRWI | Mawavi Run | 89 | 97 | 97 | 52 | 72 | 62 |
| PRWI | NF Quantico Creek | 14 | 42 | 25 | 48 | 77 | 36 |
| PRWI | Orenda Run | 89 | 93 | 97 | 98 | 100 | 54 |
| PRWI | SF Quantico Creek | 2 | 12 | 50 | 19 | 47 | 74 |
| PRWI | Sow Run | 31 | 29 | 46 | 18 | 45 | 46 |
| PRWI | Taylor Run | 45 | 75 | 82 | 29 | 72 | 52 |
| ROCR | Battery Kemble Creek | 81 | 8 | 49 | 63 | 92 | 23 |
| ROCR | Broad Branch | 43 | 85 | 93 | 68 | 91 | 33 |
| ROCR | Dumbarton Oaks | 83 | 48 | 82 | 13 | 57 | 3 |
| ROCR | Fenwick Branch | 84 | 25 | 71 | 80 | 95 | 37 |
| ROCR | Klingle Valley Creek | 1 | 15 | 66 | 51 | 9 | 3 |
| ROCR | Luzon Branch | 38 | 22 | 28 | 13 | 23 | 3 |
| ROCR | Normanstone Branch | 13 | 39 | 28 | 6 | 9 | 5 |
| ROCR | Pinehurst Branch | 13 | 29 | 47 | 3 | 9 | 55 |
| ROCR | Piney Branch | 55 | 58 | 66 | 88 | 57 | 8 |
| ROCR | Reservation 630 | 92 | 68 | 99 | 79 | 96 | 74 |
| ROCR | Rock Cr Dumbarton | 85 | 7 | 63 | 88 | 41 | 80 |
| WOTR | Courthouse Creek | 92 | 18 | 92 | 6 | 15 | 35 |
| WOTR | Wolf Trap Creek | 43 | 12 | 71 | 10 | 31 | 37 |
Individual Park Synopses
Antietam National Battlefield
Sharpsburg Creek was the only stream sampled for the 2019–2022 round of I&M monitoring at Antietam. Although the monitoring site is in a rural setting, the Sharpsburg Creek watershed upstream of the site is in a human influenced environment. Compared to other similar Highlands regional streams it is much higher in both agriculture and urbanization, including impervious surfaces, and low in forest (Table 9).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | % Tanytarsini | % Swimmer | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | % Diptera | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mumma Spring | 2004 | 20 | 25 | 95 | 84 | 93 | 99 | 92 | 93 | 98 | 98 | 78 | 74 | 100 | 86 | 99 | 79 | 3 | 95 |
| Newcomer Spring | 2004 | 20 | 58 | 91 | 49 | 97 | 96 | 92 | 93 | 98 | 100 | 78 | 72 | 100 | 86 | 98 | 77 | 5 | 95 |
| Sharpsburg Creek | 2004 | 94 | 98 | 100 | 94 | 55 | 37 | 52 | 22 | 51 | 98 | 77 | 36 | 100 | 100 | 99 | 64 | 7 | 96 |
| Sharpsburg Creek | 2006 | 94 | 98 | 100 | 94 | 66 | 53 | 52 | 47 | 77 | 100 | 65 | 82 | 100 | 100 | 99 | 89 | 12 | 93 |
| Sharpsburg Creek | 2013 | 94 | 98 | 100 | 94 | 66 | 45 | 63 | 29 | 42 | 89 | 74 | 85 | 100 | 100 | 99 | 90 | 12 | 98 |
| Sharpsburg Creek | 2022 | 94 | 98 | 100 | 94 | 33 | 16 | 31 | 10 | 69 | 98 | 73 | 83 | 100 | 100 | 99 | 89 | 8 | 98 |
Sharpsburg Creek rates as “poor” on the BIBI (Figure 1, Table 10) and shows no appreciable change since the last round of monitoring (Figure 8). However, there appear to be substantive improvements in % Ephemeroptera and % urban intolerant with a slight decline in taxa richness and % Diptera (Figure 8). The stream is dominated by amphipods (Myers et al. 2026), likely due to its high calcium content.
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Tanytarsini | Percent Scrapers | Percent Swimmers | Percent Diptera | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|---|---|
| Mumma Spring | 2004 | 1.5 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Newcomer Spring | 2004 | 1.5 | 6 | 1 | 1 | 0 | 0 | 1 | 6 | 0 |
| Sharpsburg Creek | 2004 | 2.3 | 5 | 2 | 1 | 0 | 5 | 21 | 0 | 0 |
| Sharpsburg Creek | 2006 | 2.5 | 11 | 2 | 2 | 3 | 20 | 3 | 7 | 1 |
| Sharpsburg Creek | 2013 | 2.0 | 11 | 2 | 1 | 1 | 7 | 2 | 7 | 0 |
| Sharpsburg Creek | 2022 | 2.0 | 7 | 2 | 1 | 1 | 9 | 3 | 2 | 1 |
NPS / ROBERT HILDERBRAND
With respect to its peers, most attributes rank Sharpsburg Creek as generally average to above average habitat quality, but poor for most ecological attributes (Table 9).
Catoctin Mountain Park
Three streams were sampled during the most recent monitoring round (2019–2022) in Catoctin Mountain Park: Big Hunting Creek, Blue Blazes Creek, and Owens Creek.
All three streams have average amounts of urbanization, impervious surfaces, and forest, and generally lower amounts of agriculture in their upstream watersheds compared to peer streams (Table 11). The lower amounts of human activities likely contribute to Big Hunting Creek and Owens Creek rating as “fair” on the BIBI and having generally good BIBI metrics (Table 12). Blue Blazes Creek was an anomaly with a “poor” BIBI score and notable decline in condition compared to previous sampling rounds (Figure 9). Blue Blazes Creek scored the highest in previous rounds in Catoctin Mountain Park and is expected to return to more normal values in the next round of sampling.
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | % Tanytarsini | % Swimmer | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | % Diptera | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Big Hunting Creek | 2006 | 36 | 40 | 29 | 11 | 75 | 43 | 70 | 54 | 38 | 99 | 72 | 12 | 35 | 82 | 57 | 40 | 14 | 29 |
| Big Hunting Creek | 2010 | 36 | 40 | 29 | 11 | 30 | 24 | 37 | 5 | 51 | 100 | 61 | 12 | 0 | 98 | 11 | 29 | 45 | 42 |
| Big Hunting Creek | 2022 | 36 | 40 | 29 | 11 | 75 | 24 | 70 | 43 | 63 | 97 | 72 | 5 | 97 | 78 | 91 | 15 | 64 | 72 |
| Blue Blazes Creek | 2010 | 30 | 34 | 17 | 10 | 100 | 100 | 99 | 99 | 100 | 90 | 74 | 27 | 15 | 53 | 13 | 25 | 14 | 19 |
| Blue Blazes Creek | 2022 | 30 | 34 | 17 | 10 | 85 | 39 | 83 | 93 | 71 | 100 | 77 | 39 | 99 | 57 | 90 | 58 | 92 | 91 |
| Owens Creek | 2010 | 35 | 41 | 34 | 11 | 69 | 57 | 75 | 17 | 43 | 99 | 72 | 11 | 2 | 97 | 18 | 36 | 51 | 50 |
| Owens Creek | 2022 | 35 | 41 | 34 | 11 | 79 | 21 | 66 | 77 | 91 | 100 | 72 | 18 | 91 | 51 | 80 | 48 | 79 | 78 |
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Tanytarsini | Percent Scrapers | Percent Swimmers | Percent Diptera | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|---|---|
| Big Hunting Creek | 2006 | 4.2 | 28 | 14 | 4 | 1 | 31 | 38 | 9 | 45 |
| Big Hunting Creek | 2010 | 4.0 | 39 | 20 | 8 | 4 | 9 | 38 | 29 | 18 |
| Big Hunting Creek | 2022 | 3.4 | 17 | 8 | 5 | 1 | 9 | 46 | 40 | 48 |
| Blue Blazes Creek | 2010 | 4.5 | 31 | 19 | 6 | 1 | 24 | 25 | 9 | 67 |
| Blue Blazes Creek | 2022 | 2.6 | 13 | 8 | 4 | 0 | 10 | 21 | 61 | 65 |
| Owens Creek | 2010 | 3.8 | 37 | 18 | 5 | 1 | 6 | 35 | 32 | 25 |
| Owens Creek | 2022 | 3.1 | 18 | 9 | 3 | 1 | 10 | 30 | 49 | 68 |
NPS / ROBERT HILDERBRAND
Stream habitat attributes were variable across Catoctin streams. Blue Blazes Creek was generally of poorer quality compared to peer streams, and the other streams generally of average quality. All streams had higher amounts of fine sediments (as indicated by their embeddedness) than peers. Ecological condition using the BIBI was average for Big Hunting Creek and Owens Creek and low for Blue Blazes Creek compared to peers. The individual metrics varied from above to below average compared to peers.
George Washington Memorial Parkway
Four streams were sampled during the most recent monitoring round (2019–2022) in George Washington Memorial Parkway (GWMP): Mine Run, Minnehaha Creek, Pimmit Run, and Turkey Run. GWMP streams tend to be in urbanized watersheds compared to peers even if the streams are mostly forested on NPS lands (Table 13). Mine Run has the best overall ecological condition as measured by the BIBI (Figure 1) and rated as “fair”. The remaining sites all rated as “poor” for the current sampling round, and all were dominated by Chironomidae and had low % urban intolerant values (Table 14).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mine Run | 2004 | 25 | 60 | 1 | 0 | 75 | 24 | 59 | 39 | 61 | 49 | 100 | 88 | 100 | 97 | 100 | 100 | 100 |
| Mine Run | 2012 | 25 | 60 | 1 | 0 | 96 | 61 | 100 | 35 | 47 | 31 | 85 | 60 | 94 | 62 | 87 | 96 | 61 |
| Mine Run | 2022 | 25 | 60 | 1 | 0 | 89 | 5 | 91 | 35 | 38 | 53 | 99 | 69 | 94 | 88 | 99 | 99 | 97 |
| Minnehaha | 2014 | 57 | 29 | 42 | 20 | X | X | X | X | X | X | 16 | 37 | 49 | 19 | 79 | 6 | 26 |
| Minnehaha | 2022 | 57 | 29 | 42 | 20 | 29 | 4 | 35 | 55 | 85 | 20 | 91 | 79 | 80 | 73 | 68 | 90 | 95 |
| Pimmit Run | 2004 | 68 | 53 | 46 | 15 | 45 | 22 | 52 | 8 | 20 | 45 | 99 | 82 | 94 | 78 | 92 | 82 | 99 |
| Pimmit Run | 2006 | 68 | 53 | 46 | 15 | 28 | 22 | 10 | 4 | 93 | 25 | 47 | 72 | 75 | 33 | 21 | 63 | 76 |
| Pimmit Run | 2012 | 68 | 53 | 46 | 15 | 74 | 28 | 100 | 8 | 20 | 45 | 4 | 67 | 75 | 33 | 57 | 26 | 20 |
| Pimmit Run | 2022 | 68 | 53 | 46 | 15 | 28 | 14 | 69 | 78 | 63 | 45 | 92 | 82 | 91 | 78 | 83 | 89 | 98 |
| Turkey Run | 2004 | 69 | 99 | 43 | 11 | 72 | 85 | 46 | 42 | 88 | 36 | 85 | 93 | 87 | 93 | 100 | 100 | 99 |
| Turkey Run | 2012 | 69 | 99 | 43 | 11 | 77 | 29 | 46 | 36 | 84 | 83 | 89 | 94 | 100 | 98 | 100 | 86 | 99 |
| Turkey Run | 2022 | 69 | 99 | 43 | 11 | 8 | 4 | 58 | 59 | 77 | 66 | 87 | 88 | 97 | 96 | 99 | 99 | 99 |
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Minnehaha Creek | 2014 | 2.0 | 25 | 3 | 1 | 36 | 16 | 3 |
| Minnehaha Creek | 2022 | 1.0 | 12 | 1 | 0 | 95 | 22 | 0 |
| Mine Run | 2004 | 1.3 | 17 | 3 | 1 | 93 | 7 | 2 |
| Mine Run | 2012 | 3.3 | 25 | 6 | 3 | 58 | 49 | 17 |
| Mine Run | 2022 | 2.3 | 20 | 6 | 2 | 68 | 33 | 13 |
| Pimmit Run | 2004 | 1.0 | 7 | 0 | 0 | 83 | 17 | 0 |
| Pimmit Run | 2006 | 1.7 | 22 | 2 | 1 | 69 | 44 | 1 |
| Pimmit Run | 2012 | 2.3 | 32 | 2 | 1 | 46 | 32 | 1 |
| Pimmit Run | 2022 | 1.1 | 13 | 0 | 0 | 91 | 22 | 0 |
| Turkey Run | 2004 | 1.7 | 21 | 7 | 1 | 86 | 9 | 5 |
| Turkey Run | 2012 | 1.7 | 20 | 2 | 0 | 49 | 19 | 3 |
| Turkey Run | 2022 | 1.9 | 21 | 4 | 1 | 76 | 32 | 15 |
Most ecological aspects declined for most sites compared to the previous sampling round (Figure 10). However, Turkey Run improved on several metrics even though its overall BIBI did not substantively change.
NPS / ROBERT HILDERBRAND
Most ecological attributes at all sites had lower values compared to their peer streams (Table 13). However, stream physical habitat was mostly equivalent or better than peer streams, and riffle quality in particular was better than most peers and should provide good benthic macroinvertebrate habitats.
Harpers Ferry National Historical Park
Flowing Springs Run was the only stream sampled for the 2019–2022 round of I&M monitoring at Harpers Ferry. Although the monitoring site is in a rural setting, the Flowing Springs Run watershed upstream of the site is in a human influenced environment with higher amounts of urbanization and impervious surface cover (ISC). Compared to peer streams, it ranks unfavorably for urbanized land uses, but very well for low agriculture (Table 15).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | % Tanytarsini | % Swimmer | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | % Diptera | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Flowing Springs Run | 2004 | 93 | 100 | 61 | 15 | 4 | 80 | 24 | 14 | 73 | 97 | 65 | 61 | 45 | 86 | 76 | 74 | 82 | 77 |
| Flowing Springs Run | 2013 | 93 | 100 | 61 | 15 | 91 | 48 | 80 | 47 | 41 | 13 | 78 | 71 | 68 | 86 | 89 | 77 | 90 | 95 |
| Flowing Springs Run | 2022 | 93 | 100 | 61 | 15 | 61 | 5 | 80 | 17 | 41 | 55 | 76 | 66 | 94 | 80 | 93 | 73 | 73 | 96 |
Flowing Springs Run rates very poor ecologically (Figure 1; Table 16). It is dominated by Diptera and contains very low % urban intolerant individuals. The BIBI score did not change appreciably from the last sampling round (Figure 11) but has declined since the first visit in 2004 (Table 16). Nonetheless, there were improvements in % urban intolerant, % swimmer, and % Tanytarsini (Figure 11).
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Tanytarsini | Percent Scrapers | Percent Swimmers | Percent Diptera | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|---|---|
| Elks Run Downstream | 2004 | 2.8 | 11 | 6 | 4 | 0 | 5 | 74 | 1 | 45 |
| Flowing Springs Run | 2004 | 2.3 | 27 | 6 | 2 | 3 | 4 | 5 | 67 | 0 |
| Flowing Springs Run | 2013 | 1.5 | 23 | 4 | 1 | 0 | 3 | 2 | 76 | 0 |
| Flowing Springs Run | 2022 | 1.4 | 16 | 3 | 1 | 0 | 1 | 3 | 61 | 7 |
NPS / ROBERT HILDERBRAND
Flowing Springs Run is generally worse ecologically than its peer streams (Table 15). In contrast, it rates similar or better than its peers for stream physical habitat, with riffle quality and instream habitat ranking in the upper 25th percentile.
Manassas National Battlefield Park
Young’s Branch was the only stream sampled at Manassas National Battlefield Park. The stream resides in a low-urban watershed that has substantial impervious surfaces because of road density and reflects this compared to peer streams (Table 17). The stream rates as ecologically “fair” (Figure 1), which makes it one of the better rated streams in the NCR I&M Network.
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chinn’s Branch | 2004 | 13 | 100 | 35 | 0 | 100 | 100 | 100 | 97 | 99 | 53 | 97 | 85 | 98 | 97 | 100 | 94 | 99 |
| Young’s Branch | 2004 | 9 | 99 | 38 | 0 | 89 | 100 | 96 | 80 | 90 | 53 | 100 | 91 | 100 | 100 | 96 | 97 | 100 |
| Young’s Branch | 2010 | 9 | 99 | 38 | 0 | 55 | 78 | 18 | 73 | 86 | 80 | 2 | 90 | 86 | 97 | 57 | 92 | 92 |
| Young’s Branch | 2022 | 9 | 99 | 38 | 0 | 75 | 70 | 67 | 91 | 86 | 25 | 92 | 87 | 96 | 52 | 78 | 84 | 85 |
Compared to the last time it was sampled, the stream has improved with respect to an increase in the % urban intolerant individuals and an increase in Ephemeroptera richness (Table 18, Figure 12).
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Chinn’s Branch | 2004 | 2.0 | 22 | 5 | 1 | 56 | 29 | 5 |
| Young’s Branch | 2004 | 1.7 | 13 | 0 | 0 | 59 | 41 | 0 |
| Young’s Branch | 2010 | 2.7 | 37 | 7 | 1 | 53 | 62 | 1 |
| Young’s Branch | 2022 | 2.9 | 24 | 5 | 3 | 48 | 54 | 3 |
NPS / ROBERT HILDERBRAND
Chinn’s Branch was dropped from monitoring because it would sometimes go dry.
Young’s Branch does not compare favorably to peer streams for most ecological attributes (Table 17). However, it compares well for embeddedness while lagging for several other stream physical habitat attributes.
Monocacy National Battlefield
Bush Creek and Gambrill Mill Creek were the two streams sampled in Monocacy National Battlefield. Bush Creek occupies a large watershed in a mixed landscape with urbanization high in the catchment and a mix of forest and agriculture farther down. Gambrill Mill Creek resides in a mix of land uses, and both branches upstream of the sampling site parallel roads for much of their length. Because of its size, Bush Creek had few peers, and it rated high in impervious surface cover (ISC) and low in agriculture in comparison (Table 19). Despite its physical appearance, Bush Creek rated as “very poor” ecologically (Figure 1), and it has declined in condition since the last monitoring visit (Table 20; Figure 13). Bush Creek was dominated by Chironomidae, had very low % urban intolerant individuals, and generally low taxa richness (Table 20). The sharp decline from the previous sampling suggests a serious decline or possible anomaly in sampling because even the BIBI for the full 200 individual count (not presented) rates as “poor.” In contrast, Gambrill Mill Creek rated ecologically as “fair” (Figure 1) and improved on several metrics compared to the previous sampling (Figure 13).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bush Creek | 2004 | 29 | 90 | 60 | 2 | 100 | 94 | 100 | 100 | 100 | 72 | 100 | 12 | 96 | 81 | 100 | 89 | 88 |
| Bush Creek | 2010 | 29 | 90 | 60 | 2 | 28 | 100 | 4 | 33 | 22 | 25 | 47 | 91 | 92 | 60 | 69 | 38 | 77 |
| Bush Creek | 2022 | 29 | 90 | 60 | 2 | 100 | 12 | 100 | 53 | 95 | 72 | 100 | 89 | 99 | 91 | 99 | 100 | 100 |
| Gambrill Mill Creek | 2004 | 51 | 84 | 78 | 91 | 88 | 96 | 91 | 95 | 84 | 46 | 51 | 94 | 96 | 93 | 76 | 66 | 92 |
| Gambrill Mill Creek | 2010 | 51 | 84 | 78 | 91 | 91 | 97 | 91 | 48 | 77 | 46 | 64 | 94 | 100 | 98 | 100 | 96 | 98 |
| Gambrill Mill Creek | 2022 | 51 | 84 | 78 | 91 | 85 | 29 | 86 | 86 | 77 | 89 | 73 | 63 | 91 | 56 | 85 | 91 | 79 |
| Harding’s Run | 2004 | 6 | 60 | 26 | 61 | 97 | 92 | 79 | 72 | 86 | 65 | 57 | 56 | 24 | 52 | 34 | 10 | 23 |
| South Fork Gambrill Mill | 2004 | 94 | 69 | 63 | 7 | 10 | 5 | 25 | 8 | 35 | 40 | 40 | 67 | 74 | 47 | 84 | 69 | 48 |
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Bush Creek | 2004 | 2.7 | 19 | 5 | 2 | 57 | 16 | 32 |
| Bush Creek | 2010 | 3.0 | 28 | 6 | 3 | 34 | 53 | 3 |
| Bush Creek | 2022 | 1.4 | 16 | 3 | 1 | 81 | 23 | 5 |
| Gambrill Mill Creek | 2004 | 2.7 | 27 | 5 | 1 | 36 | 57 | 4 |
| Gambrill Mill Creek | 2010 | 2.0 | 25 | 2 | 0 | 63 | 11 | 4 |
| Gambrill Mill Creek | 2022 | 3.2 | 24 | 6 | 3 | 54 | 52 | 37 |
NPS / ROBERT HILDERBRAND
Bush Creek ranks well below peer streams for every ecological metric (Table 19). In contrast, Gambrill Mill Creek was similar to the average peer stream for half of the metrics and below average for the others.
Regarding stream physical habitat, Gambrill Mill Creek ranks average on riffle quality compared to peer streams, and poorly on the other metrics. Bush Creek fares much better compared to peers for riffle quality and average or below on the other stream physical habitat attributes (Table 19).
National Capital Parks - East
Henson Creek, Oxon Run, and Still Creek were the three streams sampled in National Capital Parks - East (NACE) for the most recent round of sampling (2019–2022). All streams are in an urban landscape, yet Still Creek (in Greenbelt Park) and Henson Creek (in Suitland Parkway) have lower amounts of urbanization and impervious surface cover (ISC) compared to peer streams (Table 21). Ecologically, none of the streams fare well with Henson Creek rating as “poor,” Oxon Run as “very poor,” and Still Creek as “poor” (Figure 1). All sites markedly decreased in the number of taxa and had very low % urban intolerant individuals (Table 22), which is indicative of degradation and often a signature of urbanization. Most aspects of ecological condition have declined compared to previous sampling (Figure 14), especially for Still Creek.
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Scraper Richness | Taxa Richness | % Urban Intolerant | EPT Richness | % Ephemeroptera | Ephemeroptera Richness | % Climber | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Accokeek Creek | 2004 | 16 | 27 | 4 | 9 | 27 | 60 | 45 | 41 | 58 | 87 | 71 | 53 | 94 | 77 | 70 | 64 | 73 | 70 |
| Accokeek Creek | 2013 | 16 | 27 | 4 | 9 | 55 | 19 | 35 | 41 | 31 | 87 | 57 | 0 | 93 | 17 | 56 | 1 | 41 | 29 |
| Henson Creek | 2013 | 23 | 71 | 37 | 26 | 49 | 3 | 56 | 9 | 10 | 27 | 69 | 44 | 77 | 43 | 43 | 28 | 5 | 35 |
| Henson Creek | 2022 | 23 | 71 | 37 | 26 | 49 | 2 | 12 | 55 | 39 | 39 | 69 | 61 | 77 | 65 | 64 | 50 | 69 | 55 |
| Oxon Run | 2006 | 40 | 81 | 37 | 23 | 29 | 4 | 12 | 35 | 74 | 76 | 77 | 91 | 83 | 81 | 77 | 79 | 88 | 93 |
| Oxon Run | 2013 | 40 | 81 | 37 | 23 | 68 | 24 | 100 | 25 | 51 | 46 | 63 | 46 | 83 | 81 | 77 | 79 | 70 | 65 |
| Oxon Run | 2022 | 40 | 81 | 37 | 23 | 58 | 9 | 42 | 67 | 19 | 53 | 87 | 98 | 82 | 81 | 77 | 79 | 80 | 95 |
| Still Creek | 2004 | 1 | 32 | 0 | 26 | 9 | 48 | 3 | 9 | 39 | 27 | 69 | 44 | 45 | 30 | 68 | 72 | 41 | 59 |
| Still Creek | 2013 | 1 | 32 | 0 | 26 | 14 | 6 | 19 | 36 | 39 | 46 | 19 | 5 | 72 | 43 | 57 | 4 | 51 | 9 |
| Still Creek | 2022 | 1 | 32 | 0 | 26 | 14 | 4 | 30 | 36 | 10 | 39 | 69 | 63 | 77 | 60 | 68 | 72 | 37 | 61 |
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Urban Intolerant | Number of Scraper Taxa | Percent Ephemeroptera | Percent Climbers |
|---|---|---|---|---|---|---|---|---|---|
| Henson Creek | 2013 | 3.0 | 21 | 3 | 1 | 0 | 1 | 4 | 60 |
| Henson Creek | 2022 | 2.5 | 18 | 1 | 1 | 0 | 1 | 1 | 12 |
| Oxon Run | 2006 | 1.6 | 13 | 0 | 0 | 0 | 1 | 0 | 2 |
| Oxon Run | 2013 | 2.7 | 24 | 0 | 0 | 0 | 2 | 0 | 12 |
| Oxon Run | 2022 | 1.4 | 8 | 0 | 0 | 0 | 0 | 0 | 7 |
| Still Creek | 2004 | 2.4 | 21 | 4 | 0 | 5 | 1 | 0 | 28 |
| Still Creek | 2013 | 3.9 | 32 | 3 | 2 | 1 | 4 | 2 | 22 |
| Still Creek | 2022 | 2.4 | 17 | 2 | 0 | 0 | 1 | 0 | 31 |
NPS / ROBERT HILDERBRAND
Despite the recent declines, Henson Creek’s condition is above average, and Still Creek is average when compared to peer streams (Table 21). Other ecological metrics align similarly to the BIBI such that both Henson Creek and Still Creek are average to above average compared to their peers.
Stream physical habitat generally compares well to peer streams, with all three NACE streams having average or better habitat attributes. Accokeek Creek monitoring was discontinued because the stream would periodically dry out, while the lower portions were tidal.
Prince William Forest Park
The nine streams sampled during the most recent round in Prince William Forest Park (PRWI) were Boneyard Run, Carter’s Run, Mary Byrd Branch, Mawavi Run, North Fork Quantico Creek, Orenda Run, South Fork Quantico Creek, Sow Run, and Taylor Run. PRWI streams were generally better than most other National Capital Region streams, in part because of low urbanization and more forest in their watersheds. These streams also compare well against peer streams with respect to land use (Table 23).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Boneyard Run | 2021 | 9 | 20 | 1 | 13 | 89 | 100 | 73 | 52 | 99 | 42 | 86 | 88 | 84 | 92 | 62 | 47 | 89 |
| Carter’s Run | 2011 | 10 | 37 | 1 | 13 | 94 | 99 | 99 | 97 | 99 | 98 | 83 | 80 | 97 | 91 | 50 | 87 | 96 |
| Carter’s Run | 2021 | 10 | 37 | 1 | 13 | 58 | 62 | 10 | 74 | 50 | 72 | 98 | 88 | 90 | 93 | 34 | 36 | 84 |
| Mary Byrd Branch | 2011 | 8 | 19 | 0 | 9 | 85 | 80 | 91 | 59 | 84 | 46 | 3 | 67 | 12 | 39 | 95 | 75 | 47 |
| Mary Byrd Branch | 2021 | 8 | 19 | 0 | 9 | 31 | 42 | 46 | 11 | 34 | 27 | 95 | 48 | 61 | 23 | 8 | 18 | 39 |
| Mawavi Run | 2011 | 9 | 19 | 1 | 13 | 89 | 99 | 94 | 97 | 100 | 98 | 10 | 30 | 29 | 60 | 26 | 39 | 23 |
| Mawavi Run | 2021 | 9 | 19 | 1 | 13 | 89 | 97 | 97 | 52 | 72 | 62 | 90 | 80 | 86 | 97 | 56 | 34 | 84 |
| Middle Branch Chopawamsik | 2004 | 8 | 17 | 1 | 9 | 21 | 10 | 10 | 11 | 34 | 46 | 64 | 70 | 71 | 62 | 7 | 32 | 47 |
| Middle Branch Chopawamsik | 2011 | 8 | 17 | 1 | 9 | 43 | 69 | 35 | 36 | 97 | 89 | 0 | 77 | 0 | 2 | 57 | 60 | 47 |
| NF Quantico Creek | 2011 | 9 | 31 | 1 | 9 | 77 | 56 | 86 | 48 | 67 | 46 | 9 | 86 | 38 | 7 | 35 | 27 | 21 |
| NF Quantico Creek | 2021 | 9 | 31 | 1 | 9 | 14 | 42 | 25 | 48 | 77 | 36 | 99 | 95 | 98 | 70 | 8 | 19 | 88 |
| North Branch Chopawamsik | 2004 | 8 | 21 | 1 | 9 | 31 | 56 | 16 | 36 | 67 | 42 | 76 | 87 | 71 | 62 | 9 | 20 | 61 |
| North Branch Chopawamsik | 2006 | 8 | 21 | 1 | 9 | 21 | 29 | 3 | 18 | 45 | 56 | 85 | 80 | 38 | 39 | 35 | 68 | 47 |
| North Branch Chopawamsik | 2011 | 8 | 21 | 1 | 9 | 43 | 69 | 46 | 48 | 90 | 93 | 0 | 71 | 0 | 0 | 66 | 39 | 33 |
| Orenda Run | 2011 | 11 | 66 | 2 | 13 | 45 | 97 | 49 | 94 | 100 | 98 | 69 | 47 | 91 | 91 | 31 | 23 | 62 |
| Orenda Run | 2021 | 11 | 66 | 2 | 13 | 89 | 93 | 97 | 98 | 100 | 54 | 98 | 82 | 96 | 92 | 74 | 45 | 93 |
| SF Quantico Creek | 2021 | 0 | 15 | 0 | 0 | 2 | 12 | 50 | 19 | 47 | 74 | 100 | 43 | 48 | 8 | 13 | 23 | 31 |
| Sow Run | 2021 | 8 | 18 | 0 | 9 | 31 | 29 | 46 | 18 | 45 | 46 | 97 | 72 | 88 | 52 | 74 | 75 | 82 |
| Taylor Run | 2011 | 9 | 18 | 1 | 13 | 22 | 62 | 16 | 29 | 92 | 80 | 4 | 56 | 3 | 1 | 47 | 66 | 49 |
| Taylor Run | 2021 | 9 | 18 | 1 | 13 | 45 | 75 | 82 | 29 | 72 | 52 | 75 | 79 | 49 | 29 | 48 | 36 | 50 |
The only streams rated as ecologically “good” across the entire National Capital Region were both PRWI streams: Mary Byrd Branch and Taylor Run (Figure 1). Boneyard Run, North Fork Quantico Creek, and Orenda Run rated as “poor,” and the remainder rated as “fair.” Many PRWI sites had elevated % urban intolerant relative to other NPS sites, but the overall taxa richness declined in many streams from the previous round of monitoring (Table 24). Carter’s Run improved on the BIBI and other aspects since the last sampling, whereas North Fork Quantico Creek and Orenda both declined noticeably (Figure 15).
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Boneyard Run | 2021 | 2.8 | 20 | 7 | 1 | 24 | 64 | 20 |
| Carter’s Run | 2011 | 2.3 | 21 | 4 | 1 | 49 | 70 | 28 |
| Carter’s Run | 2021 | 3.0 | 14 | 6 | 1 | 19 | 77 | 20 |
| Mawavi Run | 2011 | 4.7 | 35 | 13 | 3 | 20 | 82 | 64 |
| Mawavi Run | 2021 | 3.0 | 19 | 7 | 0 | 17 | 67 | 28 |
| Mary Byrd Branch | 2011 | 4.0 | 38 | 15 | 4 | 41 | 42 | 34 |
| Mary Byrd Branch | 2021 | 4.2 | 18 | 10 | 5 | 9 | 93 | 48 |
| Middle Branch Chopawamsik | 2004 | 4.0 | 25 | 9 | 3 | 18 | 95 | 32 |
| Middle Branch Chopawamsik | 2011 | 4.0 | 55 | 20 | 7 | 33 | 66 | 26 |
| North Fork Quantico Creek | 2011 | 4.7 | 35 | 12 | 6 | 15 | 76 | 16 |
| North Fork Quantico Creek | 2021 | 2.8 | 14 | 4 | 3 | 10 | 93 | 2 |
| North Branch Chopawamsik | 2004 | 3.7 | 23 | 9 | 3 | 10 | 92 | 15 |
| North Branch Chopawamsik | 2006 | 4.0 | 21 | 12 | 4 | 37 | 76 | 23 |
| North Branch Chopawamsik | 2011 | 4.3 | 49 | 20 | 9 | 22 | 62 | 31 |
| Orenda Run | 2011 | 3.7 | 24 | 6 | 1 | 11 | 79 | 53 |
| Orenda Run | 2021 | 2.6 | 15 | 5 | 1 | 23 | 58 | 26 |
| South Fork Quantico Creek | 2021 | 3.8 | 18 | 10 | 5 | 25 | 79 | 25 |
| Sow Run | 2021 | 3.1 | 16 | 7 | 3 | 41 | 58 | 30 |
| Taylor Run | 2011 | 4.0 | 38 | 18 | 8 | 34 | 71 | 47 |
| Taylor Run | 2021 | 4.0 | 23 | 11 | 5 | 19 | 71 | 29 |
NPS / ROBERT HILDERBRAND
Compared to peer streams, Mary Byrd Branch and South Fork Quantico Creek were well above average for numerous ecological metrics, whereas Boneyard Run, Carter’s Run, Mawavi Run, North Fork Quantico Creek, and Orenda Run all compared poorly to peer streams (Table 23).
Stream physical habitat was quite variable when compared to peer streams but generally followed the same patterns as with ecological metrics. Mary Byrd Branch, South Fork Quantico Creek, and Sow Run habitat attributes were generally superior to peer streams, whereas Boneyard Run and Orenda Run were lower than peers (Table 23).
Rock Creek Park
Rock Creek Park (ROCR) had 11 sites sampled in the latest round of monitoring. This is an urban park and has many challenges associated with ecological condition of streams in urban landscapes. Most of the sites were near the middle to upper end of urbanized land uses compared to peers (Table 25).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Battery Kemble Creek | 2014 | 92 | 100 | 81 | 13 | X | X | X | X | X | X | 63 | 97 | 99 | 97 | 100 | 99 | 99 |
| Battery Kemble Creek | 2022 | 92 | 100 | 81 | 13 | 81 | 8 | 49 | 63 | 92 | 23 | 97 | 97 | 99 | 97 | 100 | 100 | 100 |
| Broad Branch | 2008 | 57 | 55 | 38 | 21 | 17 | 33 | 4 | 18 | 21 | 76 | 54 | 79 | 92 | 73 | 47 | 74 | 56 |
| Broad Branch | 2019 | 57 | 55 | 38 | 21 | 43 | 85 | 93 | 68 | 91 | 33 | 85 | 28 | 22 | 0 | 28 | 48 | 6 |
| Dumbarton Oaks | 2014 | 20 | 59 | 6 | 26 | X | X | X | X | X | X | 42 | 2 | 38 | 70 | 73 | 6 | 38 |
| Dumbarton Oaks | 2019 | 20 | 59 | 6 | 26 | 83 | 48 | 82 | 13 | 57 | 3 | 93 | 77 | 48 | 14 | 83 | 29 | 88 |
| Fenwick Branch | 2008 | 87 | 92 | 86 | 20 | 17 | 12 | 10 | 5 | 4 | 37 | 3 | 79 | 49 | 19 | 45 | 41 | 26 |
| Fenwick Branch | 2019 | 87 | 92 | 86 | 20 | 84 | 25 | 71 | 80 | 95 | 37 | 90 | 79 | 78 | 22 | 79 | 81 | 96 |
| Klingle Valley Creek | 2014 | 85 | 82 | 85 | 26 | X | X | X | X | X | X | 35 | 64 | 83 | 70 | 92 | 7 | 38 |
| Klingle Valley Creek | 2019 | 85 | 82 | 85 | 26 | 1 | 15 | 66 | 51 | 9 | 3 | 72 | 77 | 30 | 0 | 66 | 45 | 36 |
| Luzon Branch | 2008 | 74 | 92 | 77 | 26 | 83 | 15 | 99 | 0 | 3 | 55 | 50 | 77 | 62 | 70 | 63 | 8 | 38 |
| Luzon Branch | 2019 | 74 | 92 | 77 | 26 | 38 | 22 | 28 | 13 | 23 | 3 | 91 | 77 | 94 | 70 | 87 | 63 | 99 |
| Normanstone Branch | 2014 | 58 | 61 | 46 | 26 | X | X | X | X | X | X | 7 | 0 | 17 | 3 | 53 | 15 | 0 |
| Normanstone Branch | 2019 | 58 | 61 | 46 | 26 | 13 | 39 | 28 | 6 | 9 | 5 | 91 | 77 | 32 | 0 | 77 | 73 | 88 |
| Pinehurst Branch | 2008 | 36 | 14 | 19 | 26 | 23 | 39 | 28 | 0 | 5 | 65 | 71 | 77 | 83 | 70 | 91 | 55 | 86 |
| Pinehurst Branch | 2019 | 36 | 14 | 19 | 26 | 13 | 29 | 47 | 3 | 9 | 55 | 84 | 77 | 63 | 0 | 71 | 44 | 65 |
| Piney Branch | 2014 | 81 | 99 | 80 | 26 | X | X | X | X | X | X | 42 | 77 | 83 | 3 | 80 | 48 | 86 |
| Piney Branch | 2019 | 81 | 99 | 80 | 26 | 55 | 58 | 66 | 88 | 57 | 8 | 97 | 77 | 62 | 3 | 63 | 30 | 88 |
| Reservation 630 | 2008 | 33 | 59 | 17 | 26 | 83 | 22 | 99 | 1 | 5 | 35 | 18 | 67 | 38 | 3 | 65 | 69 | 86 |
| Reservation 630 | 2019 | 33 | 59 | 17 | 26 | 92 | 68 | 99 | 79 | 96 | 74 | 65 | 48 | 17 | 40 | 75 | 50 | 76 |
| Rock Cr Dumbarton | 2004 | 95 | 100 | 31 | 0 | X | X | X | X | X | X | 77 | 72 | 83 | 90 | 64 | 81 | 89 |
| Rock Cr Dumbarton | 2022 | 95 | 100 | 31 | 0 | 85 | 7 | 63 | 88 | 41 | 80 | 95 | 62 | 89 | 90 | 0 | 94 | 90 |
| Soapstone Valley Stream | 2008 | 57 | 75 | 46 | 26 | 13 | 15 | 14 | 1 | 5 | 55 | 10 | 77 | 38 | 3 | 14 | 56 | 5 |
All streams rated as ecologically “poor” or “very poor” with respect to benthic macroinvertebrates (Figure 1). All sites had low % urban intolerant individuals, and most were dominated by Chironomidae (Table 26). This is no surprise given the surrounding urbanized landscape. Broad Branch improved in ecological condition compared to the last sampling, but Fenwick Branch, Luzon Branch, and Normanstone Branch showed declines in the overall BIBI score (Figure 16).
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Battery Kemble Creek | 2014 | 1.7 | 25 | 2 | 0 | 73 | 19 | 0 |
| Battery Kemble Creek | 2022 | 1.2 | 16 | 2 | 0 | 84 | 18 | 0 |
| Broad Branch | 2008 | 1.7 | 19 | 0 | 0 | 81 | 31 | 0 |
| Broad Branch | 2019 | 2.4 | 14 | 5 | 5 | 67 | 40 | 3 |
| Dumbarton Oaks | 2014 | 1.7 | 20 | 3 | 0 | 36 | 17 | 6 |
| Dumbarton Oaks | 2019 | 1.3 | 11 | 3 | 1 | 57 | 10 | 0 |
| Fenwick Branch | 2008 | 2.0 | 30 | 3 | 1 | 63 | 32 | 0 |
| Fenwick Branch | 2019 | 1.0 | 12 | 1 | 1 | 86 | 16 | 0 |
| Klingle Valley Creek | 2014 | 1.7 | 21 | 1 | 0 | 37 | 2 | 1 |
| Klingle Valley Creek | 2019 | 1.7 | 16 | 3 | 2 | 66 | 20 | 0 |
| Luzon Branch | 2008 | 1.7 | 19 | 2 | 0 | 38 | 22 | 0 |
| Luzon Branch | 2019 | 1.0 | 12 | 0 | 0 | 76 | 7 | 0 |
| Normanstone Branch | 2014 | 2.3 | 27 | 4 | 1 | 46 | 26 | 12 |
| Normanstone Branch | 2019 | 1.3 | 12 | 3 | 2 | 82 | 14 | 0 |
| Pinehurst Branch | 2008 | 1.3 | 16 | 1 | 0 | 72 | 3 | 0 |
| Pinehurst Branch | 2019 | 1.5 | 13 | 2 | 2 | 66 | 17 | 0 |
| Piney Branch | 2014 | 1.3 | 20 | 1 | 1 | 68 | 12 | 0 |
| Piney Branch | 2019 | 1.3 | 9 | 2 | 1 | 58 | 22 | 0 |
| Reservation 630 | 2008 | 1.3 | 24 | 3 | 1 | 79 | 21 | 1 |
| Reservation 630 | 2019 | 1.4 | 17 | 4 | 0 | 69 | 15 | 2 |
| Rock Creek at Dumbarton Oaks | 2004 | 1.7 | 18 | 2 | 0 | 81 | 38 | 2 |
| Rock Creek at Dumbarton Oaks | 2022 | 1.7 | 13 | 1 | 0 | 94 | 77 | 3 |
| Soapstone Valley Stream | 2008 | 2.0 | 26 | 3 | 1 | 72 | 49 | 0 |
NPS / ROBERT HILDERBRAND
Despite the urban landscape surrounding the streams, ROCR streams compare favorably to other peer streams of similar size in the same geographic region (Table 25). Broad Branch had a BIBI score well above its peer. Several streams also had higher total taxonomic richness and richness of Ephemeroptera and EPT (Ephemeroptera, Plecoptera, and Trichoptera) compared to peers.
Stream habitat quality was also high compared to peer streams, with higher riffle quality, pool quality, epifaunal substrate (macroinvertebrate habitat), overall instream habitat, and lower embeddedness. For an urban watershed, the stream physical habitat in ROCR streams is quite good.
The sites sampled within Rock Creek Park are all ecologically degraded, yet they fare better than streams in similar settings in the region.
Wolf Trap National Park for the Performing Arts
Courthouse Creek and Wolf Trap Creek flow through suburban and exurban landscapes. They both have moderate to high amounts of urban land uses and impervious surface cover (ISC) and lower amounts of forest and agriculture compared to peer streams (Table 27).
| Site | Year | % Urban | % Impervious Surfaces | % Forest | % Agriculture | Velocity/Depth | Riffle Quality | Pool Quality | lnstream Habitat | Epifaunal Substrate | Embeddedness | Taxa Richness | % Urban Intolerant | EPT Richness | Ephemeroptera Richness | % Clinger | % Chironomidae | BIBI |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Courthouse Creek | 2004 | 41 | 87 | 29 | 26 | X | X | X | X | X | X | 90 | 77 | 62 | 70 | 48 | 49 | 99 |
| Courthouse Creek | 2012 | 41 | 87 | 29 | 26 | 70 | 29 | 92 | 3 | 23 | 35 | 13 | 21 | 6 | 0 | 70 | 17 | 0 |
| Courthouse Creek | 2022 | 41 | 87 | 29 | 26 | 92 | 18 | 92 | 6 | 15 | 35 | 71 | 50 | 76 | 5 | 39 | 82 | 55 |
| Wolf Trap Creek | 2004 | 46 | 60 | 29 | 20 | 9 | 42 | 4 | 18 | 77 | 37 | 74 | 54 | 82 | 73 | 66 | 73 | 83 |
| Wolf Trap Creek | 2006 | 46 | 60 | 29 | 20 | 43 | 42 | 53 | 10 | 31 | 57 | 32 | 13 | 67 | 19 | 35 | 55 | 56 |
| Wolf Trap Creek | 2012 | 46 | 60 | 29 | 20 | 17 | 12 | 1 | 1 | 4 | 37 | 4 | 68 | 67 | 19 | 57 | 22 | 26 |
| Wolf Trap Creek | 2022 | 46 | 60 | 29 | 20 | 43 | 12 | 71 | 10 | 31 | 37 | 85 | 79 | 70 | 73 | 18 | 85 | 75 |
Both Wolf Trap Creek and Courthouse Creek were rated as “very poor” ecologically (Figure 1). Both sites were dominated by Chironomidae and had low % urban intolerant individuals (Table 28). Both sites also declined for most ecological attributes since the last sampling (Figure 17).
| Site | Year | BIBI | Number of Taxa | Number of EPT Taxa | Number of Ephemeroptera Taxa | Percent Chironomidae | Percent Clingers | Percent Urban Intolerant |
|---|---|---|---|---|---|---|---|---|
| Courthouse Creek | 2004 | 1.0 | 12 | 2 | 0 | 68 | 29 | 0 |
| Courthouse Creek | 2012 | 2.7 | 25 | 5 | 2 | 48 | 18 | 3 |
| Courthouse Creek | 2022 | 1.6 | 16 | 1 | 1 | 88 | 33 | 2 |
| Wolf Trap Creek | 2004 | 1.3 | 16 | 1 | 0 | 81 | 23 | 2 |
| Wolf Trap Creek | 2006 | 1.7 | 22 | 2 | 1 | 71 | 37 | 5 |
| Wolf Trap Creek | 2012 | 2.0 | 29 | 2 | 1 | 52 | 27 | 1 |
| Wolf Trap Creek | 2022 | 1.4 | 14 | 2 | 0 | 90 | 46 | 0 |
NPS / ROBERT HILDERBRAND
While degraded, both streams actually compared somewhat favorably to peer streams, with both sites mostly average for ecological condition and most of the component metrics (Table 27).
Both streams compare favorably to peer streams for most stream physical habitat attributes, with several attributes in the top 25%.
Literature Cited
- Anh, N.T., L.D. Can, N.T. Nhan, B. Schmalz, and T.L. Luu. 2023. Influences of key factors on river water quality in urban and rural areas: A review. Case Studies in Chemical and Environmental Engineering 8: 100424. https://doi.org/10.1016/j.cscee.2023.100424
- Bonada, N., N. Prat, V.H. Resh, and B. Statzner. 2006. Developments in aquatic insect biomonitoring: a comparative analysis of recent approaches. Annual Review of Entomology 51: 495–523. https://doi.org/10.1146/annurev.ento.51.110104.151124
- Dewitz, J., and U.S. Geological Survey. 2021. National Land Cover Database (NLCD) 2019 Products (ver. 3.0, February 2024): U.S. Geological Survey data release. https://doi.org/10.5066/P9KZCM54
- Hilderbrand, R., M. Peipoch, M. Norris, and G. Sanders. 2025. National Capital Region Network Biological Stream Survey Data Package - cumulative through 2022. National Park Service. Fort Collins, Colorado. https://doi.org/10.57830/2314911
- Hilderbrand, R., M. Peipoch, M. Norris, and G. Sanders. 2026. National Capital Region Network Biological Stream Survey Data Package - cumulative through 2022. National Park Service. Fort Collins, Colorado. https://doi.org/10.57830/2318473
- Hilderbrand, R., P. Kazyak, R. Raesly, and D. Curtis. 2005. Baseline water resource inventory to support aquatic watershed management activities in National Capital Region parks. Report to the National Park Service National Capital Region.
- Karr, J.R., K.D. Fausch, P.L. Angermeier, P.R. Yant, and I.J. Schlosser. 1986. Assessment of biological integrity in running waters: A method and its rationale. Illinois Natural History Survey Special Publication 5. Champaign, Illinois.
- Kenney, M.A., A. Sutton-Grier, R.F. Smith, and S. Gresens. 2009. Benthic macroinvertebrates as indicators of water quality: The intersection of science and policy. Terrestrial Arthropod Reviews 2: 99–128. https://doi.org/10.1163/187498209X12525675906077
- Leppo, E. 2021. MBSStools: MBSS tool suite for calculations and data manipulation. R package version 1.2.0.9001. https://github.com/leppott/MBSStools
- Myers, D.T., R. Hilderbrand, and E. Brentjens. 2026. Supplemental information for biological stream survey report. National Park Service. Washington, DC. https://irma.nps.gov/DataStore/Reference/Profile/2318321
- Norris, M.E., and G. Sanders. 2009. National Capital Region Network biological stream survey protocol: Physical habitat, fish, and aquatic macroinvertebrate vital signs. Natural Resource Report NPS/NCRN/NRR—2009/116. National Park Service, Fort Collins, Colorado.
- O’Driscoll, M., S. Clinton, A. Jefferson, A. Manda, and S. McMillan. 2010. Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States. Water 2(3): 605–648. https://doi.org/10.3390/w2030605
- Oksanen, J., G. Simpson, F. Blanchet, R. Kindt, P. Legendre, P. Minchin, R. O’Hara, P. Solymos, M. Stevens, et al. 2024. vegan: Community Ecology Package. R package version 2.6-8. https://CRAN.R-project.org/package=vegan
- R Core Team. 2025. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/
- Russell, K.L., G.J. Vietz, and T.D. Fletcher. 2018. Urban catchment runoff increases bedload sediment yield and particle size in stream channels. Anthropocene 23: 53–66. https://doi.org/10.1016/j.ancene.2018.09.001
- Schiff, R., and G. Benoit. 2007. Effects of impervious cover at multiple scales on coastal watershed streams. Journal of the American Water Resources Association 43: 712–730. https://doi.org/10.1111/j.1752-1688.2007.00057.x
- Stribling, J.B., B.K. Jessup, J.S. White, D. Boward, and M. Hurd. 1998. Development of a Benthic Index of Biotic Integrity for Maryland Streams. Report to Monitoring and Non-Tidal Assessment Division, Maryland Department of Natural Resources, Annapolis, Maryland. CBWP-EA-98-3
- U.S. National Park Service. 2024. Inventory and Monitoring. National Park Service. https://www.nps.gov/articles/000/im_inventory-and-monitoring-program-brief.htm
- Utz, R.M., R.H. Hilderbrand, and D.M. Boward. 2009. Identifying regional differences in threshold responses of aquatic invertebrates to land cover gradients. Ecological Indicators 9: 556–567.
Author Information
Robert H. Hilderbrand 
https://orcid.org/0000-0003-0923-7699
University of Maryland
Center for Environmental Science
Appalachian Laboratory
301 Braddock Rd.
Frostburg, MD 21532
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