PRINCIPAL INVESTIGATOR
      Gene E. Likens
      Institute of Ecosystem Studies

OTHERS INVOLVED
      see References

BEGIN DATE
       June 1967

END DATE
      On-going

LOCATION
      Outlet to Mirror Lake

LOCATION DESCRIPTION
       Collected from below the Mirror Lake dam, but above the USGS stream-gauging flume. The dam is a concrete and stone structure, with un-treated, wooden spillway boards, that remain in place year-round. Outflow from the lake over the dam varies from 1 to 1000 L/sec, depending on lake pool level and seasonal hydrology. Mirror Lake is 15 ha in size, 11 m deep, and an oligotrophic, clearwater, natural water body adjacent toHBEF. Numerous studies have been conducted on Mirror Lake since the mid-1960s, including extensive physical, chemical, biological, and paleoecological research which are described in detail in the book: An Ecosystem Approach to Aquatic Ecology (Likens, 1985).

DATA DESCRIPTION
       Concentrations (mg/L) in weekly streamwater samples. Base cations and pH are available since 1967. Ammonium, anions, and dissolved silica have been measured since 1970, and phosphate was routinely determined first in 1972, although some data are available for each solute prior to these dates.

SAMPLING DESIGN
       Samples are collected in acid-washed, deionized water-rinsed, polyethylene bottles, from water flowing over the spillway boards. The normal sampling interval is weekly, with more frequent samples taken at times of increased discharge. At low lake pool levels, samples may be taken from leakage through small gaps in the boards.

REFERENCES

• Likens, G. E. 1972. Mirror Lake: its past, present and future? Appalachia 39(2):23- 41.
• Likens, G. E. (editor). 1985. An Ecosystem Approach to Aquatic Ecology: Mirror Lake and its Environment. Springer-Verlag New York Inc. 516 pp.
• Buso, D.C., G.E. Likens, and J.S. Eaton. 2000. Chemistry of precipitation, streamwater, and lakewater from the Hubbard Brook Ecosystem Study: a record of sampling protocols and analytical procedures. Gen. Tech. Rep. NE-275. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 52 p.

  ACCESS
         Public, from 6-1967 to 12-1995. 5-year withholding policy in effect for these data.

  DATA LOCATION
        Institute of Ecosystem Studies, Robert S. Pierce Ecosystem Laboratory, Hubbard Brook Experimental Forest, W.Thornton, NH

  LAST UPDATED
         April, 2001

  CONTACT PERSON
        Gene Likens
        Institute of Ecosystem Studies
        Millbrook, NY 12545
        Telephone: (845) 677-5343
        E-mail: LikensG@ecostudies.org

  VARIABLES
         Records: 1039 samples
         Columns: supplied with the following headers:
              ws - watershed (designated as 70)
              year - year
              mo - month
              dy - day
              Ca - calcium concentration in mg/L
              Mg - magnesium concentration in mg/L
              K - potassium concentration in mg/L
              Na - sodium concentration in mg/L
              NH4 - ammonium concentration in mg/L
              pH - pH
              SO4 - sulfate concentration in mg/L
              NO3 - nitrate concentration in mg/L
              Cl - chloride concentration in mg/L
              PO4 - phosphate concentration in mg/L (soluble-reactive phosphate)
              SiO2 - silica concentration in mg/L (measured as silicate)

  CODES
         Missing data are coded with -3

  DATA FILE NAME(S)
         ASCII file name: ml-out.txt