State of the Streams 2024

Methods – Access

Tree Equity 

Background: In addition to providing climate benefits, trees are important to human health and to the economy. According to American Forests, “trees often are sparse in low-income neighborhoods and some neighborhoods of color. In fact, policies from the early 1900’s are still shaping the way redlining contributes to periods of disinvestment, exacerbating tree inequity in these neighborhoods”.

The Tree Equity Score was developed by American Forests to calculate whether communities have enough trees for community members to “experience the health, economic, and other benefits that trees provide.” Going beyond just the impact of trees on climate, this indicator specifically considers other ways trees benefit human communities and takes into account population density to ensure enough trees are present per person. (American Forests) 

Data: Tree Equity Scores, already calculated by American Forests, were obtained for census block groups within each watershed. 

Threshold and scoring: The average tree equity score (across census block groups) was calculated for each watershed; this average score is the overall Tree Equity score for each watershed. 

Park Access

Background:  Access to green space, which in urban areas is most often in the form of parks, is vital to support human health and resilient communities (NRPA, 10-Minute Walk, The Trust for Public Land). The NRPA defines park access as “The just and fair quantity, proximity and connections to quality parks and green space, recreation facilities, as well as programs that are safe, inclusive, culturally relevant and welcoming to everyone”. The distribution of parks in cities is an important consideration in environmental justice, and park access may not be equitably distributed across or within all cities (Bara et al. 2021, Miller 2019). 

The Trust for Public Land leads a national effort to ensure that cities across the country provide adequate park access to their citizens. This effort, called 10 Minute Walk, has identified a target of establishing parks and green spaces within so that all city residents live within 10 minutes walking distance of a park. 

Data: The ParkServe database, calculated and provided by The Trust for Public Land, provides information on the total population of neighborhoods and communities, and on the number of people within each community that are within a 10-minute walk from a park. We downloaded these numbers for each neighborhood and community within the three watersheds. 

Threshold and scoring:  For each neighborhood or community within each watershed, the percentage of the population within a 10-minute walk of a park was calculated. The average score across communities within each watershed was the overall Park Access score for that watershed.