MASON LAKE -- MASON COUNTY: 1997

Mason Lake is located eight miles southwest of Belfair. It is four miles long and is fed by Shumocher Creek. Mason Lake drains via Sherwood Creek to North Bay and Case Inlet. It is the largest and deepest lake in Mason County.

Size (acres)                        1000
Maximum Depth (feet)                  90
Mean Depth (feet)                     48
Lake Volume (acre-feet)            48000
Drainage Area (square miles)       20.20
Altitude (feet)                      194
Shoreline Length (miles)            10.9

Contour Map

Source of morphometric data: Water Supply Bulletins 42, 43, and 57.


VOLUNTEER-COLLECTED SECCHI DATA ________________________________________________________________________________________________________________________ Date Temperature Water %Cloud Recent Secchi Lake (Y/M/D) (C) (F) pH Color Cover Rain Wind (ft) Ht(in) Abbrev. Comments ________________________________________________________________________________________________________________________ STATION 2 97/05/31 18.0 64.4 6.5 Undefined 100 Mod Light 17.0 0.0 WATER DARK GREEN IN COLOR 97/06/13 20.0 68.0 6.5 Lt Green 50 None Calm 22.0 0.0 97/06/30 20.0 68.0 6.5 Lt Green 75 Light Calm 23.0 0.0 97/07/12 21.0 69.8 6.5 Lt Green 75 Trace Calm 22.0 0.0 97/07/30 24.0 75.2 6.5 Lt Green 90 None Calm 23.0 0.0 VIEW TUBE USED FOR BOTH SECCHI READINGS. 97/08/12 24.0 75.2 6.3 Lt Green 2 None Calm 25.0 0.0 97/08/28 23.0 73.4 6.5 Lt Green 50 Heavy Calm 21.0 0.0 97/09/11 22.0 71.6 6.3 Undefined 90 Trace Calm 21.0 0.0 WATER WAS DARK GREEN. 97/09/26 1.0 33.8 6.3 Lt Green 0 None Calm 22.0 0.0 STATION 3 97/06/12 -6.9 19.5 Lt Green 50 Trace Light 20.5 25.0 97/06/25 19.0 66.2 Lt Green 10 Trace Light 22.0 0.0 97/07/10 20.0 68.0 6.5 Lt Green 50 Heavy Breezy 21.0 0.0 97/07/23 23.0 73.4 6.5 Lt Green 25 None Calm 22.0 0.0 97/08/08 25.0 77.0 6.5 Lt Green 10 Light 25.0 0.0 97/08/22 24.0 75.2 7.0 Lt Green 0 Light Calm 26.0 0.0 ALGAE BLOOM. 97/09/07 24.0 75.2 6.5 Lt Green 0 None Calm 28.0 0.0 97/10/04 18.0 64.4 6.5 Lt Green 100 Heavy Strong 18.0 0.0 ROTTEN DAY TO DO THIS. STATION 4 97/06/24 18.3 64.9 6.3 Lt Green 90 Light Calm 24.0 324.8 97/07/02 19.4 66.9 6.5 50 Trace Light 24.0 348.0 GONE DOWN 1.25 INCHESSINCE 6-24. IN THAT PERIOD HAD .47" RAIN. 97/07/18 21.1 70.0 6.5 Lt Green 75 None Calm 21.0 348.3 97/08/05 25.0 77.0 6.5 Undefined 25 None Calm 25.0 32.0 97/08/15 25.0 77.0 6.5 Lt Green 2 None Calm 25.0 0.0 97/09/01 Lt Green 0 None Calm 22.6 0.0 97/09/04 22.2 72.0 6.7 Lt Green 10 None Calm 25.0 31.8 97/09/15 20.0 68.0 6.5 Lt Green 100 Heavy Calm 22.0 31.5 97/09/22 21.0 69.8 6.5 Lt Green 0 None Calm 21.0 0.0 97/10/04 18.0 64.4 6.5 Lt Green 100 Heavy Strong 16.0 0.0 ________________________________________________________________________________________________________________________
LABORATORY RESULTS ________________________________________________________________________________________________________________________ Total Total Fecal Col. Bacteria Turb- Suspended Solids Phosphorus Nitrogen Chlorophyll (colonies/100 mL) idity Total Non-Volatile Color Date Strata (ug/L) (mg/L) (ug/L) Site 1 Site 2 (NTU) (mg/L) (mg/L) (Pt-Co) ________________________________________________________________________________________________________________________ STATION 2 97/06/05 E 4 0.03 STATION 4 97/06/05 E 4 0.10 97/06/05 H 5 0.03 97/09/01 E 15 0.08 1.9 97/09/01 H 20 0.05 ________________________________________________________________________________________________________________________ E=epilimnion composite, H=hypolimnion composite. Remarks codes: U = Below detection limits; J = Estimate.
SUMMARY OF VOLUNTEER SURVEY There was no survey response for 1997. FIELD OBSERVATIONS OF ECOLOGY STAFF 6-5-97 Highest water level noted in years this past February. 9-1-97 2 osprey observed. Moderate boating for a holiday.
TROPHIC STATUS Estimated Trophic State: Oligo-mesotrophic Mean Trophic State Index (Secchi): 32 (Oligotrophic) Mean Trophic State Index (Total Phosphorus): 43 (Mesotrophic) Mean Trophic State Index (Chlorophyll a): 37 (Oligotrophic)
SUMMARY AND EXPLANATION OF TROPHIC STATE ASSESSMENT Although Secchi depth remains favorable in Mason Lake, phosphorus and chlorophyll concentrations depict a lake that is slightly more eutrophic than the Secchi data may infer. Additionally, summertime hypolimnetic DO concentrations are depleted and there was a moderate blue-green algal bloom in the summer. All considering, an oligo-mesotrophic assessment is justified.
COMMENTS FROM 98/09/14 AQUATIC PLANT SURVEY Sunny, calm. Surveyed entire shoreline, did habitat survey for Dave Hallock. Plants patchy, occasional dense areas of P. amplifolius, but many areas with open sediment. Much tiny ball-like algae suspended in water. M. spicatum only seen in Paradise Estates launch area. Observed a loon at south end, herons, few mallards, fish, osprey, heard frogs (didn't sound like adult bullfrogs). Maximum depth of plant growth: 6.0M.
AQUATIC PLANT LIST (This list may be from multiple years and sources.) Brasenia schreberi (watershield) Callitriche sp. (water-starwort) Carex obnupta (slough sedge) Carex sp. (sedge) Chara sp. (muskwort) Elodea canadensis (common elodea) Equisetum sp. (horse tail) Hippuris vulgaris (common marestail) Iris pseudacorus (yellow flag) Isoetes sp. (quillwort) Juncus sp. (rush) Juncus sp. or Eleocharis sp. (small grass-like plants) Lilaeopsis occidentalis (lilaeopsis) Lobelia dortmanna (water gladiole; water lobelia) Myriophyllum sp. (water-milfoil) Myriophyllum spicatum (Eurasian water-milfoil) Najas flexilis (common naiad) Nitella sp. (stonewort) Nuphar polysepala (spatter-dock, yellow water-lily) Phalaris arundinacia (reed canarygrass) Potamogeton amplifolius (large-leaf pondweed) Potamogeton epihydrus (ribbonleaf pondweed) Potamogeton gramineus (grass-leaved pondweed) Potamogeton illinoensis (Illinois pondweed) Potamogeton natans (floating leaf pondweed) Potamogeton robbinsii (fern leaf pondweed) Potamogeton sp (thin leaved) (thin leaved pondweed) Potamogeton sp. (pondweed) Ranunculus aquatilis (water-buttercup) Sagittaria graminea (slender arrowhead) Scirpus sp. (bulrush) Utricularia sp. (bladderwort) Vallisneria americana (water celery)


Data collected and provided by Washington Department of Ecology's Lake Monitoring Program (Maggie Bell-McKinnon, phone 360- 407-6124).

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