Creek geomorphology was measured during the growing season. Fractures, defined as a visible break in the high marsh (S. patens-dominated) turf that paralleled the creek channel (Fig. S1) within 3 m of the S. alterniflora/S. patens border were measured early in the growing season before the grass obscured fractures. Both sides of each creek were sampled for fractures in contiguous 50m reaches from the 0-m mark to 250-300-m landward. The number of fractures and their characteristics (length, width and depth of fracture) was recorded within each reach. Percent mud was determined by point-intercept transects in the mid growing season, when the grass canopy was fully developed, at 1-m increments for both sides of each creek channel starting at the 0-m mark and extending landward 250-300 m in contiguous 50-m reaches. Observations were made 1-m perpendicular and creekward of the S. alterniflora/S. patens border. Each meter was scored as “vegetated” – with S. alterniflora culms within a 30 cm diameter circle of the point, or “bare mud” – without S. alterniflora. The fraction of points within each 50 m reach was considered a single observation. Year - The calender year the data was collected Years enriched- The number of years creeks have experienced artificial nutrient enrichment Creeks- Reference creeks are West and Nelson Nutrient Enriched creeks are Sweeney and Clubhead. Sweeney has been fertilized every summer from 2004-2012 Clubhead had been fertilized in 2005 and then from 2009-2012. Section - Four reaches within each tidal creek were sampled. One = 0-50 m, two =50-100m, three=100=150m, four=150-200m All creeks have 2 branches (left and right) determined by remaining at confluence of branches and facing upland areas.