Maryland Biological Stream Survey

Spring and Summer Sampling Seasons

The MBSS samples sites around the state from March to October. This is split into two different index periods, spring (March - April) and summer (June - September). Each sampling season has its own protocols and goals. The section below gives a general description of each index period. For more detailed information on specific protocols and data sheets, view the MBSS protocol manual

Spring Season

MBSS sampling crews visit each site three times in a sampling year. During spring (March and April), crews mark sites, take pictures, install continuously reading temperature loggers (water and air), and collect water and benthic macroinvertebrate samples. Spring habitat data includes surrounding land use, stream gradient and channelization, and riparian vegetation. Crews also document vernal pools and conduct a qualitative search for herpetofauna, freshwater mussels, and crayfish.

Summer Season

Summer sampling takes place from June through September. Quantitative fish sampling includes two pass electrofishing, complete counts of all game and non-game fish, and measuring of individual game fish lengths. Discharge, average stream width, depth, and velocity, bank erosion, woody debris and rootwads, instream habitat quality, shading, and embeddedness are among the many physical habitat measurements taken by MBSS crews during summer. Using a water quality and turbidity meter, we record water chemistry and clarity. Crews also conduct faunal searches for:

  • invasive riparian plants
  • stream salamanders
  • crayfish
  • turtles
  • lizards
  • snakes
  • frogs
  • and freshwater mussels


In October, we return to sample sites to retrieve temperature loggers and download their data.