Phosphorus reduction by dilution and shift in fish species in Moses Lake, WA

Figures & data

Figure 1 Moses Lake showing the source of Columbia River dilution water from the East Low Canal (1) entering via Rocky Coulee Wasteway (2) into Crab Creek and then into Parker Horn. Water sampling sites are shown by number and solid lines for transects.

Table 1 Mean TP, chl and transparency (SD) during May–September in Parker Horn (PH) and South Lake (SL) of Moses Lake. Data are based on transect samples collected at 0.5 m (Welch et al., 1989), and for discrete samples at 0.5 m in 2001 (Carroll 2006). Data omitted were from 1985, due to high internal loading (see text), and 1984, the year of diversion and no dilution water addition. Trophic state boundaries from Nürnberg (1996).

	TP (μg/L)		CHL (μg/L)		SD (m)
Lake Section	PH	SL	PH	SL	PH	SL
Pre-dilution, 1969–1970	152	156	71	42	0.6	1.0
Dilution, pre-diversion, 1977–1983	67	85	23	18	1.3	1.5
Dilution, post-diversion, 1986–1988	47	41	21	12	1.5	1.7
2001	18	17	11	10	2.0	2.1
Hypereutrophic/eutrophic boundary	100		25		1.0
Eutrophic/mesotrophic boundary	25		9		2.0

Figure 2 The quantity of Columbia River dilution water in 10⁶ m³ (solid bars) added during spring-early summer to Parker Horn of Moses Lake from the East Low Canal through Rocky Coulee Wasteway and Crab Creek. Clear bars are water exchange rates for the Parker Horn volume in %/day for the 6-month dilution period, and whole-lake volume is 154 × 10⁶ m³.

Figure 3 Angler catch* in 1974, 1983, 1991 and 1996, and biological sampling (electrofishing and gill netting) in the other years, expressed as % of total catch, shown at the top of bars for each year (Burgess 2000, Burgess et al. 2007).

Table 2 Switch in fish populations associated with change from hypereutrophy and lower eutrophy (3-yr mean, 1974–1983) and to borderline mesotrophy (5-year mean, 1989–2000). Data from Burgess (2000).

		3 yrs:		5 yrs:
Species		1974–1983		1989–2000
Bluegill/ crappie	Decreased	34–89% (57%)	TO	1–27% (9.2%)
Smallmouth bass	Increased	< 1% (< 1%)	TO	1–12% (6.4%)
Walleye	Increased	0- < 1% (< 1%)	TO	12–41% (18.1%)
Brown bullhead	Increased	1–2% (1.5%)	TO	3–18% (10.4%)
Largemouth bass	Decreased	1–16% (7%)	TO	0.1–5.2% (2.5%)

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Burgess , D. 2000 . Moses Lake Fishery Restoration Project – 1998–1999 Annual Report . : 167 Proj. No. 199502800, BPA Report DOE/BP-00006320-1

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Burgess , D. , Simmons , K. and Shipley , R. 2007 . Moses Lake Fishery Restoration Project, 2005–2006 Annual Report . : 68 Proj. No. 199502800, BPA Report DOE/BP-00029385-2

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