Aluminum treatments to control internal phosphorus loading in lakes on Cape Cod, Massachusetts

Figures & data

Figure 1. Locations of treatment lakes on Cape Cod, MA. Base map from Acme Mapper 2.1.

Table 1. Features of lakes treated with aluminum between 1995 and 2015.

		Depth				Hydrologic load		Phosphorus load
	Area	Mean	Maximum	Detention		Precipitation	Groundwater	Internal	Surface Flow	Groundwater
Lake	ha	m	m	yr	Tributaries	%	%	%	%	%
Hamblin	46.0	8.3	18.8	1.0	No	11	87	67	9	11
Ashumet	82.0	7.0	20.0	1.9	No	17	72	47	4	45
Long	296.0	8.8	21.2	3.5	No	51	44	64	17	9
Mystic	59.0	4.6	14.3	1.0	No	18	80	46	15	21
Lovers	15.0	4.6	10.0	1.2	No	39	55	43	27	12
Stillwater	7.5	6.8	13.9	1.2	From Lovers	13	25	55	32	5
Herring	17.7	6.2	10.9	2.8	No	42	55	40	1	46
Great	44.7	3.6	11.0	0.4	2 small ones	14	83	26	8	45
Lovell's	22.0	5.7	11.4	2.1	1 diverted	43	53	62	4	16
Cliff	83.0	8.6	26.7	5.3	No	71	23	67	5	6

Figure 2. Dose response curve for Fe-P in (a) 6 sediment samples from Mystic Lake and (b) 5 sediment samples from Cliff Pond treated with aluminum in the laboratory.

Table 2. Information for 12 treatments of 10 lakes on Cape Cod.

			Aluminum application
			Treatment area		Treatment dose
	Year	Season
Lake	Treated	Treated	ha	% of lake	g/m^2	max. mg/L
Hamblin	1995	Spring	32.3	69.6	45	9.0
Hamblin	2015	Spring	27.0	58.7	45–71	4.5
Ashumet	2001	Summer	11.3	13.8	43	4.3
Ashumet	2010	Fall	22.8	27.8	40	4.0
Long	2007	Fall	148.0	50.0	10–30	3.0
Mystic	2010	Fall	23.2	39.3	30–50	3.3
Lovers	2010	Fall	10.0	66.7	100	5.0
Stillwater	2010	Fall	5.0	66.7	100	5.0
Herring	2012	Fall	8.0	45.2	75	5.0
Great	2013	Fall	11.2	25.1	25	5.0
Lovell's	2014	Spring	14.0	63.6	50	2.5
Cliff	2016	Spring	31.0	37.3	75	3.8

Figure 3. Treatment zones and dates of treatment (month/day in 2007) for Long Pond.

Table 3. Summary of pre- and post-treatment monitoring results for treated Cape Cod lakes.

	Surface total P		Bottom total P		Summer Secchi depth		Summer Chl-a		Oxygen demand
	Pre-trtmt	Post-trtmt	Pre-trtmt	Post-trtmt	Pre-trtmt	Post-trtmt	Pre-trtmt	Post-trtmt	Pre-trtmt	Post-trtmt
Lake	µg/L	µg/L	µg/L	µg/L	m	m	µg/L	µg/L	mg/m^2/d	mg/m^2/d
Hamblin 1995	42	10	454	46	1.8	5.6	21.3	2.0	1720	219
Hamblin 2015	20	7	310	13	1.9	7.8	37.9	1.2	980	515
Ashumet 2001	26	17	290	100	2.8	3.5	6.4	4.1	1034	No data
Ashumet 2010	16	10	300	60	2.9	3.8	5.7	3.2	No data	No data
Long	30	16	163	62	2.8	5.4	12.6	5.5	1823	935
Mystic	35	15	555	65	1.2	3.9	19.7	3.5	780	213
Lovers	32	12	116	24	1.0	3.0	32.2	2.4	1500	555
Stillwater	28	11	290	38	1.3	3.3	21.6	1.8	1500	311
Herring	21	11	357	21	0.5	4.4	19.0	2.9	866	334
Great	22	14	57	32	2.3	2.5	8.4	6.5	1625	300
Lovell's	61	12	167	35	2.0	4.2	14.3	2.3	1310	530
Cliff	23	5	87	12	2.0	5.7	12.6	1.8	2465	1680

Figure 4. Average summer chlorophyll a vs. Secchi transparency for study lakes.

Figure 5. Average surface total phosphorus (TP) vs. Secchi transparency for study lakes. SDT = Secchi disk transparency.

Figure 6. Average Jun–Sep biomass of major algal divisions in Long Pond before and after treatment with aluminum.

Figure 7. Biomass of major algal divisions in samples from Lovell's Pond.

Figure 8. Hypolimnetic oxygen demand in 2 basins of Long Pond over time.

Figure 9. Dissolved oxygen (DO) profiles for Hamblin Pond before (solid lines) and after (dashed lines) (a) 1995 and (b) 2015 aluminum treatments.

Figure 10. Zooplankton biomass in Hamblin Pond from June samples before and after treatment.

Figure 11. Zooplankton biomass in Lovell's Pond before and after treatment.

Figure 12. Summer Secchi transparency depths from Hamblin Pond between 1992 and 2016 through 2 aluminum treatments.

Figure 13. Summer Secchi transparency in 2 treated basins of Long Pond between 1997 and 2015.